/usr/include/opendbx/api is in libopendbx1-dev 1.4.6-11.
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* OpenDBX - A simple but extensible database abstraction layer
* Copyright (C) 2004-2009 Norbert Sendetzky <norbert@linuxnetworks.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307 USA.
*/
#include <opendbx/api.h>
#include <stdexcept>
#include <vector>
#include <string>
#ifndef ODBX_API_HPP
#define ODBX_API_HPP
extern "C++" {
/**
* OpenDBX C++ API
*
* The OpenDBX C++ API is an object-oriented database abstraction layer based
* on the procedural C API of the OpenDBX library. The C++ API provides objects
* encapsulating connections, statements, result sets and large objects.
*
* Using the API starts with establishing a connection to the database server by
* creating an instance of the Conn class with the parameters backend, host and
* port. Conn::getCapability() tests the implemented capabilites of the underlying
* database library while Conn::getOption() and Conn::setOption() has be used to
* test for and change a number of options. The options must be changed before
* authenticating the connection with the Conn::bind() method to have any effect.
* It's also possible to rebind a connection using different credentials after
* Conn::unbind() had been called. Additionally, the Conn class is able to
* escape potentially dangerous character sequences with Conn::escape() if e.g.
* user input should be part of a statement as value.
*
* The Conn::create() method creates and initializes a new statement instance
* from a SQL string. Currently, there are only simple statement objects
* implemented, which needs to be complete statements which can be sent to the
* database with Stmt::execute(). This method returns a Result object
* encapsulating one or more result sets returned by the database depending on
* the statement sent.
*
* Each result set must be retrieved using Result::getResult(), while
* Result::getRows() fetches a row from the current result set if the statement
* was a SELECT like statement. Otherwise, Result::rowsAffected() can be used
* to get the number of rows that were touched by the statement. If the statement
* may return rows, the Result::columnName() and Result::columnType() methods
* are able to provide some informations about the columns indexed from 0 to n.
* It's also possible to map the column name with the Result::columnPos() method
* to the column index which is required be the other column methods. To get
* the actual value and length of the content in the current row at the given
* position, the Result::fieldValue() and Result::fieldLength() must be called.
*
* In case the unterlying database library requires special handling of large
* objects (binary or text LOBs), the value of Result::fieldValue() has to be
* feed into the Result::getLob() method. It returns a Lob object which enables
* the application to read from and write to a large object using Lob::read()
* respectively Lob::write(). This is only necessary if the Conn::getCapability()
* method returns true when asking for ODBX_CAP_LO.
*
* If an error occurs in any of the object methods, the objects will throw an
* instance of the Exception class with extends the runtime_error exception of
* the STL. The instance contains an error message, the OpenDBX error code and
* an error type indicating the severity of the error. This information can be
* retrieved by the methods Exception::what(), Exception::getCode() and
* Exception::getType().
*
* @author Norbert Sendetzky <norbert@linuxnetworks.de>
* @version 1.0
*/
namespace OpenDBX
{
using std::string;
class Lob_Iface;
class Result_Iface;
class Stmt_Iface;
class Conn_Iface;
/**
* Exceptions thrown by the OpenDBX classes.
*
* Most calls to methods of OpenDBX objects does throw an exception in case
* an error occurs in the underlying database library. Additionally to other
* exceptions which inherit from the STL exception class it will not only
* contain a translated error message depending on the user settings but
* also a machine readable error code and an indicator for the severity of
* the eror.
*
* @author Norbert Sendetzky <norbert@linuxnetworks.de>
* @version 1.0
*/
class Exception : public std::runtime_error
{
/**
* Error code (negative).
*/
int m_error;
/**
* Severity of error (negative: fatal, zero: success, positive: warning)
*/
int m_type;
public:
/**
* Initializes the exception object.
*
* The first parameter, the error message, should be the human readable
* description of what has gone wrong. It should also be already translated
* to the language of the user which depends on his environment settings
* when e.g GNU gettext is used. Errors thrown by the OpenDBX C++ library
* are already translated.
*
* The OpenDBX error code is the machine readable code for the error which
* has been occured.
*
* The last parameter must be a value indicating the severity of the
* thrown error. If the value is smaller than zero, the error is fatal
* and the connection to the database can't be recovered and has to be
* closed and reopened before the application can try to continue. In
* case it's greater than zero, the operation failed but the database
* connection is still usable. Zero represents a successful operation
* and shouldn't be used because an exception should only be thrown in
* error conditions.
*
* @param msg Human readable error message
* @param err OpenDBX error code
* @param type Severity of error (negative: fatal, zero: success, positive: warning)
* @return Exception
*/
Exception( const string& msg, int err, int type ) throw();
/**
* Returns the OpenDBX error code related to the error.
*
* The machine readable code describing the error which occured can be
* used by the application to act differently depending on the specific
* error. Currently defined codes are:
*
* - ODBX_ERR_SUCCESS\n
* The operation was successfully completed.
* - ODBX_ERR_BACKEND\n
* An error occured in the native database library or in the
* database server.
* - ODBX_ERR_NOCAP\n
* The capability isn't available in the currently selected backend.
* - ODBX_ERR_PARAM\n
* One of the given parameters is invalid and doesn't match the
* expectations.
* - ODBX_ERR_NOMEM\n
* An out of memory condition occured.
* - ODBX_ERR_SIZE\n
* The internally allocated memory is unable to store the value.
* - ODBX_ERR_NOTEXIST\n
* The backend library wasn't found or loading the library failed.
* - ODBX_ERR_NOOP\n
* The required function isn't available or the operation isn't
* possible in this backend.
* - ODBX_ERR_OPTION\n
* The given option is unknown an therefore invalid.
* - ODBX_ERR_OPTRO\n
* The requested option is read-only and its value can't be changed.
* - ODBX_ERR_OPTWR\n
* Setting the given option to the new value failed.
* - ODBX_ERR_RESULT\n
* Waiting for the result set after sending a statement to the
* database server failed.
* - ODBX_ERR_NOTSUP\n
* The requested functionality isn't supported by the backend.
* - ODBX_ERR_HANDLE\n
* The internal data structure which should store the details for
* accessing the database are invalid.
*
* @return Error code
*/
int getCode() const throw();
/**
* Returns severity indicator.
*
* The returned value classifies the error thrown. In case it is negative,
* the error is fatal (e.g. the connection to the database is lost) and
* the application can't continue without closing and reopening the
* connection.
*
* If the value is positive, the database wasn't able to perform the
* requested action but the connection is still OK and can be used to
* send more requests to the database.
* On zero, everything was successfull and no error occured. This
* shouldn't happen when catching one of these exceptions.
*
* @return Severity of error (negative: fatal, zero: success, positive: warning)
*/
int getType() const throw();
};
/**
* Handling large objects if supported by the database.
*
* @author Norbert Sendetzky <norbert@linuxnetworks.de>
* @version 1.0
*/
class Lob
{
friend class Result;
/**
* Private implementation of object.
*/
Lob_Iface* m_impl;
/**
* Reference counter of copies.
*/
int* m_ref;
protected:
/**
* Default constructor.
*
* The default constructor isn't part of the public interface as the
* object must not be created manually. Instead, the Result::getLob()
* method is a factory for instances of the large object class.
*
* @return Lob instance
*/
Lob() throw() {};
/**
* Create large object instance.
*
* The constructor isn't part of the public interface as the object must
* not be created manually. Instead, the Result::getLob() method is a
* factory for instances of the large object class.
*
* @param impl Pointer to private implementation
* @return Lob instance
* @throws std::exception If an error occures
*/
Lob( Lob_Iface* impl ) throw( std::exception );
public:
/**
* Destroy large object instance if no other references exist.
*
* Each large object uses a reference counter to remember if the
* internal variables are shared with other objects. If this isn't the
* case or if this object is the last one referencing the variables,
* the object is cleanup up and the allocated memory freed.
*/
~Lob() throw();
/**
* Copy constructor.
*
* Enables the transfer of the internal state of an object \a ref of the same
* type to this object. Both objects share the same variables
* and the reference counter afterwards. The reference counter is
* incremented each time an object is copied and will be decremented if
* it is destroyed.
*
* @param ref Original large object instance
*/
Lob( const Lob& ref ) throw();
/**
* Assign large object instance to another one.
*
* Assigns the internal state of an object \a ref of the same type to this
* object. Both objects share the same variables and the
* reference counter afterwards. The reference counter is incremented
* each time an object is copied and will be decremented if it is
* destroyed.
*
* @param ref Large object instance
* @return Large object reference of this instance
*/
Lob& operator=( const Lob& ref ) throw();
/**
* Closes the large object and commits the changes.
*
* After reading from or writing new content into the large object, it
* should be closed to commit changes to the disk and clean up the
* resources. If this isn't done, the destructor of the object tries to
* close the large object automatically, but there's no guarantee it
* was successful as the destructor doesn't throw an exception in case
* of an error. Therefore, it's highly recommended to call this method
* once when you don't need the object any more.
*
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void close() throw( std::exception );
/**
* Reads content from large object into the buffer.
*
* To get the content of a large object, this method fetches the data
* in one or more pieces from the server and stores it into the user
* supplied buffer. The first call to read() will return the bytes from
* the beginning. The second and all other calls will store subsequent
* parts of the large object content into the buffer until the end of
* the data is reached. To reread the content a second time, you have
* to close the large object handle and reopen it again as some databases
* provide no way to reposition the internal file position indicator for
* the stream. The large object content fetched from the server is
* stored into the user supplied \a buffer up to \a buflen bytes.
*
* The method returns the number of bytes placed into \a buffer, which may
* be up to \a buflen bytes. If the end of the content is reached and no
* more data is available, the return value will be 0 (zero).
*
* @param buffer Pointer to a byte array where the data should be written to
* @param buflen Length of the given buffer in bytes
* @return Number of bytes written into the buffer
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
ssize_t read( void* buffer, size_t buflen ) throw( std::exception );
/**
* Writes data from the buffer into the large object.
*
* It sends the data supplied in buffer to the server for storing it
* inside the large object. The function can be called more than once
* to add subsequent parts of the content to the object. If it isn't a
* new or empty object, the existing data will be overwritten and
* truncated to the new size. It's not possible to update only parts of
* the content as some databases doesn't support to position the
* internal file position indicator. The data which should be send to
* the server is read from \a buffer up to \a buflen bytes.
*
*The method returns the number of bytes read from \a buffer and sent to
* the database server, which may be up to \a buflen bytes. It isn't
* guaranteed that the complete chunk was sent to the server, so the
* returned size may be less than the value in \a buflen.
*
* @param buffer Pointer to a byte array where the content is stored
* @param buflen Length of the data in the buffer in bytes
* @return Number of bytes written into the large object
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
ssize_t write( void* buffer, size_t buflen ) throw( std::exception );
};
/**
* Provides result sets from the database.
*
* @author Norbert Sendetzky <norbert@linuxnetworks.de>
* @version 1.0
*/
class Result
{
friend class Stmt;
/**
* Private implementation of object.
*/
Result_Iface* m_impl;
/**
* Reference counter of copies.
*/
int* m_ref;
protected:
/**
* Default constructor.
*
* The default constructor isn't part of the public interface as the
* object must not be created manually. Instead, the Stmt::execute()
* method is a factory for instances of the Result class.
*
* @return Result instance
*/
Result() throw() {};
/**
* Creates a Result instance.
*
* The constructor isn't part of the public interface as the object must
* not be created manually. Instead, the Stmt::execute() method is a
* factory for instances of the Result class.
*
* @param impl Pointer to private implementation
* @throws std::exception If an error occures
* @return Result instance
*/
Result( Result_Iface* impl ) throw( std::exception );
public:
/**
* Destroys a Result instance if no other references exist.
*
* Each result object uses a reference counter to remember if the
* internal variables are shared with other objects. If this isn't the
* case or if this object is the last one referencing the variables,
* the object is cleanup up and the allocated memory freed.
*/
~Result() throw();
/**
* Copy constructor.
*
* Enables the transfer of the internal state of an object \a ref of the same
* type to this object. Both objects share the same variables
* and the reference counter afterwards. The reference counter is
* incremented each time an object is copied and will be decremented if
* it is destroyed.
*
* @param ref Original result object instance
*/
Result( const Result& ref ) throw();
/**
* Assigns a Result instance to another one.
*
* Assigns the internal state of an object \a ref of the same type to this
* object. Both objects share the same variables and the
* reference counter afterwards. The reference counter is incremented
* each time an object is copied and will be decremented if it is
* destroyed.
*
* @param ref Result instance
* @return Result reference of this instance
*/
Result& operator=( const Result& ref ) throw();
/**
* Retrieves unfetched rows and cleans up the available result sets.
*
* After executing a statement, at least one result set is returned by
* the database server. In case of data manipulation statements, there
* are no rows returned but you have to clean up the result set
* nevertheless. This is usually done by calling and getResult() in a loop
* until it returns "done". In order to simplify application development,
* the finish() method does this for you.
*
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void finish() throw( std::exception );
/**
* Fetches one result set from the database server.
*
* Retrieves the result of a query statement from the database server.
* If the statement was an INSERT, UPDATE, DELETE or a similar
* statement, the number of affected rows is available via rowsAffected().
*
* The \a timeout parameter restricts the time the function is waiting for
* a result form the server. It may be NULL to wait until a result
* arrives. Otherwise, it can contain any number of seconds and
* microseconds in a timeval structure to wait for. The timeval structure
* must be set each time before calling getResult() because its content
* may get changed by the function. If the server doesn't respond within
* the timeout, the query isn't canceled! Instead, the next call to this
* function will wait for the same result set. Waiting the specified time
* may be implemented in the backends if it is possible, but there is no
* guarantee. If not, getResult() will return not before a responds
* arrives.
*
* Dependent on the native database library, it may be possible to
* retrieve all rows at once (if chunk is zero), one by one or more than
* one row at once. All positive values including zero are allowed as
* values for \a chunk If paging (more than one row at once) is not
* supported by the backend, it will use "one by one" or "all at once"
* if this is the only option provided.
*
* getResult() returns ODBX_RES_ROWS if a result set is available and
* ODBX_RES_DONE if no more results will be returned by the last
* successful query. ODBX_RES_NOROWS is returned if the statement was
* executed successfully but will not return a results set (like for
* INSERT, UPDATE and DELETE statements) and ODBX_RES_TIMEOUT indicates
* a timeout.
*
* @param timeout Pointer to a timeval struct specifying how long to wait for a result set from the database server
* @param chunk Number of rows to fetch at once from the database server (zero means all rows at once)
* @return Status or error code
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see odbxres
*/
odbxres getResult( struct timeval* timeout = NULL, unsigned long chunk = 0 ) throw( std::exception );
/**
* Makes data of next row available.
*
* Retrieves the values of a row from the current result set returned
* by getResult(). Until this function is invoked, no row and field data
* is available via fieldLength() or fieldValue() and these functions
* will throw an exception.
*
* getRow() will return ODBX_ROW_NEXT as long as rows are available
* from the result set. After the last row has been made available,
* further calls to this function will return ODBX_ROW_DONE indicating
* that the result set doesn't contain more rows.
*
* @return Status of the attempt to fetch one more row
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
odbxrow getRow() throw( std::exception );
/**
* Returns the number of rows affected by DELETE, INSERT of UPDATE statements.
*
* Returns the number of rows that have been changed by the current
* statement whose result set was retrieved by getResult() and zero
* if the database server didn't alter any rows. Affected rows are only
* returned for DELETE, INSERT or UPDATE statements and their concrete
* number depends on the database implementation. Some database server
* like MySQL may return a lower number than expected because they
* doesn't modify records whose values wouldn't change.
*
* @return Number of rows touched
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
uint64_t rowsAffected() throw( std::exception );
/**
* Returns the number of columns available in this result set.
*
* The number of columns will never change within a result set with one
* notable exception: MySQL returns all outstanding rows of a previous
* result set first if they were not fetched completely by getRow()
* before. Therefore, the column count might change in this special
* situation.
*
* @return Number of columns
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
unsigned long columnCount() throw( std::exception );
/**
* Maps the column name to the column number required by other methods.
*
* This method returns the index of the column which is named like the
* content of the string given via the parameter \a name. The column index will
* not change within the result set.
*
* @param name Name of the column in the result set
* @return Position of column in result set
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
unsigned long columnPos( const string& name ) throw( std::exception );
/**
* Returns the name of the column in the current result set.
*
* Gets the name of the column specified by \a pos in the current result
* set. The column names will not change within the result set with the
* exception of MySQL when the first result set wasn't retrieved
* completely before getResult() was called again.
*
* @param pos Position of column in result set
* @return Column name
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
const string columnName( unsigned long pos ) throw( std::exception );
/**
* Returns the type of the column in the current result set.
*
* The column type applies to all fields at the same position of the
* rows fetched via getRow(). The definitions are based on the SQL2003
* standard and the data types of the database server have to comply to
* the specification of the standard. These are:
*
* Exact numeric values:
* - ODBX_TYPE_BOOLEAN: True/false values
* - ODBX_TYPE_SMALLINT: Signed 16 bit integer
* - ODBX_TYPE_INTEGER: Signed 32 bit integer
* - ODBX_TYPE_BIGINT: Signed 64 bit integer
* - ODBX_TYPE_DECIMAL: Exact signed numeric values with user defined precision
*
* Approximate numeric values:
* - ODBX_TYPE_REAL: Approximate numeric values (signed) with 32 bit precision
* - ODBX_TYPE_DOUBLE: Approximate numeric values (signed) with 64 bit precision
* - ODBX_TYPE_FLOAT: Approximate numeric values (signed) with user defined precision
*
* String values:
* - ODBX_TYPE_CHAR: Fixed number of characters
* - ODBX_TYPE_NCHAR: Fixed number of characters using a national character set
* - ODBX_TYPE_VARCHAR: Variable number of characters
* - ODBX_TYPE_NVARCHAR: Variable number of characters using a national character set
*
* Large objects:
* - ODBX_TYPE_CLOB: Large text object
* - ODBX_TYPE_NCLOB: Large text object using a national character set
* - ODBX_TYPE_XML: XML tree in text format
* - ODBX_TYPE_BLOB: Large binary object
*
* Date and time values:
* - ODBX_TYPE_TIME: Time including hours, minutes and seconds
* - ODBX_TYPE_TIME_TZ: Time with timezone information
* - ODBX_TYPE_TIMESTAMP: Date and time
* - ODBX_TYPE_TIMESTAMP_TZ: Date and time with timezone information
* - ODBX_TYPE_DATE: Date including year, month and day
* - ODBX_TYPE_INTERVAL: Date interval
*
* Arrays and sets:
* - ODBX_TYPE_ARRAY: Array of values
* - ODBX_TYPE_MULTISET: Associative arrays
*
* External links:
* - ODBX_TYPE_DATALINK: URI locators like URL links
*
* Data types provided by database implementations which are not covered
* by the SQL2003 standard are subsumed as ODBX_TYPE_UNKNOWN.
*
* @param pos Position of column in result set
* @return Column type
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see odbxtype
*/
odbxtype columnType( unsigned long pos ) throw( std::exception );
/**
* Returns the size of the content in the current row at the specified postion.
*
* The field is part of the current row which was retrieved by the
* latest call to getRow() and is specified by the column index given by
* \a pos.
*
* @param pos Position of column in result set
* @return Size of the data in bytes
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
unsigned long fieldLength( unsigned long pos ) throw( std::exception );
/**
* Returns a pointer to the content in the current row at the specified postion.
*
* This function returns a pointer to the field data specified by the
* column index \a pos. The field is part of the current row which was
* retrieved by the latest call to getRow(). All values except binary
* objects are handed back as strings terminated by the zero character.
* This does also apply to numeric values, dates, etc. They have to be
* converted to their binary machine dependent representation before
* arithmetic operations can be done. If a value is undefined, i.e.
* "NULL" is attached to the field in the database, an equivalent NULL
* pointer is returned.
*
* @param pos Position of column in result set
* @return Pointer to the data
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
const char* fieldValue( unsigned long pos ) throw( std::exception );
/**
* Creates a large object instance if supported by the database.
*
* Returns a Lob class instance representing a large object stored in
* the database. It references the large object and provided methods for
* accessing and modifying its content.
*
* The parameter required by this method must be the value returned by
* the fieldValue() method of a large object column.
*
* This method must only be used if the underlying driver states that it
* supports large objects via the Conn::getCapabilities(). Otherwise,
* the content can be retrieved directly by the fieldValue() method.
*
* @param value Pointer to the content of a field returned by fieldValue()
* @return Large object instance
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see Lob
*/
Lob getLob( const char* value ) throw( std::exception );
};
/**
* Statement object.
*
* @author Norbert Sendetzky <norbert@linuxnetworks.de>
* @version 1.0
*/
class Stmt
{
friend class Conn;
/**
* Private implementation of object.
*/
Stmt_Iface* m_impl;
/**
* Reference counter of copies.
*/
int* m_ref;
protected:
/**
* Default constructor.
*
* The default constructor isn't part of the public interface as the
* object must not be created manually. Instead, the Conn::create()
* method is a factory for instances of the Stmt class.
*
* @return Statement instance
*/
Stmt() throw() {};
/**
* Creates a statement instance.
*
* The constructor isn't part of the public interface as the object must
* not be created manually. Instead, the Conn::create() method is a
* factory for instances of the Stmt class.
*
* @param impl Pointer to private implementation
* @throws std::exception If an error occures
* @return Statement instance
*/
Stmt( Stmt_Iface* impl ) throw( std::exception );
public:
/**
* Statement objects which can be created.
*
* Currently, only simple processing of statements is supported which
* means that the statement sent to the database server consists of the
* statement and the parameters in text form. Later on, also prepared
* statements will be available which separates parsing and execution
* with different parameters.
*/
enum Type { Simple };
/**
* Destroys the statement instance if no other references exist.
*
* Each statement object uses a reference counter to remember if the
* internal variables are shared with other objects. If this isn't the
* case or if this object is the last one referencing the variables,
* the object is cleaned up and the allocated memory freed.
*/
~Stmt() throw();
/**
* Copy constructor.
*
* Enables the transfer of the internal state of an object \a ref of the same
* type to this object. Both objects share the same variables
* and the reference counter afterwards. The reference counter is
* incremented each time an object is copied and will be decremented if
* it is destroyed.
*
* @param ref Original statement object instance
*/
Stmt( const Stmt& ref ) throw();
/**
* Assigns a statement instance to another one.
*
* Assigns the internal state of an object \a ref of the same type to this
* object. Both objects share the same variables and the
* reference counter afterwards. The reference counter is incremented
* each time an object is copied and will be decremented if it is
* destroyed.
*
* @param ref Stmt instance
* @return Statement reference of this instance
*/
Stmt& operator=( const Stmt& ref ) throw();
/**
* Executes a statement and returns a Result instance.
*
* Sends the necessary data to the database server which will execute
* the statement and return one or more result sets afterwards. The
* result sets can be fetched via the returned Result object.
*
* @return Result instance
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see Result
*/
Result execute() throw( std::exception );
};
/**
* Encapsulates a connection to a database.
*
* @author Norbert Sendetzky <norbert@linuxnetworks.de>
* @version 1.0
*/
class Conn
{
/**
* Private implementation of the connection object.
*/
Conn_Iface* m_impl;
/**
* Reference counter of copies.
*/
int* m_ref;
public:
/**
* The default constructor for newly created connection objects without
* parameters.
*
* This is method is provided to enable programmers to use connection
* objects as member variables of other classes. They are initialized
* at construction time of the encapsulating object when no values
* for backend, host and port are available yet.
*
* It's necessary to replace the created object later on by a connection
* instance where the necessary parameters have been given via one of
* the other constructors. Calling one of the member functions of an
* instance created by the default constructor isn't possible and will
* throw an exception.
*
* @return Empty connection instance
* @see #Conn( const char*, const char*, const char* )
* @see #Conn( const string&, const string&, const string& )
*/
Conn() throw();
/**
* Creates a connection object using C style string parameters.
*
* Initializes a new connection using the parameters \a backend, \a host and
* \a port, but doesn't open the connection to the database yet. This method
* allows C style strings as values for all parameters. Another constructor
* for C++ style strings is also available. It returns a new connection
* instance, which can be used to query options implemented by the driver
* or to create a statement. In case of an error, it throws an OpenDBX
* exception with error message, code and severity.
*
* The parameter \a backend is the name of the driver the OpenDBX library
* should use to connect to a database. The name must be one of the
* implemented and available drivers on the system and is case sensitive.
* All driver names are in lower case, e.g. "mysql".
*
* Depending on the database driver, \a host can have different meanings.
* Normally, it's the name or IP address of the server hosting the
* database server application. In case of serverless database
* implementations like SQLite it's the directory path where the database
* file is located. The path must contain the platform specific path
* separators like slash ("/") on Unix-like systems and backslash ("\")
* on Windows systems. Also the path must end with the path separator
* like "/path/to/file/".
*
* Furthermore \a port can be the number or name the database server
* application is listening to. If a name instead of the number is
* allowed depends on the database client library but the number as
* string does always work. If an empty string is given, the default
* port of the database server application is used by the database
* client library.
*
* @param backend Name of the backend module to use
* @param host Name or IP address of the database server
* @param port Name or number of the port used by the database server
* @return Connection instance
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see #Conn( const string&, const string&, const string& )
*/
Conn( const char* backend, const char* host = "", const char* port = "" ) throw( std::exception );
/**
* Creates a connection object using C++ style string parameters.
*
* Initializes a new connection using the parameters backend, host and
* port, but doesn't open the connection to the database yet. This method
* allows C++ style strings as values for all parameters. Another
* construtor for C style strings is also available. It returns a new
* connection instance, which can be used to query options implemented
* by the driver or to create a statement. In case of an error, it throws
* an OpenDBX exception with error message, code and severity.
*
* The parameter \a backend is the name of the driver the OpenDBX library
* should use to connect to a database. The name must be one of the
* implemented and available drivers on the system and is case sensitive.
* All driver names are in lower case, e.g. "mysql".
*
* Depending on the database driver, \a host can have different mearings.
* Normally, it's the name or IP address of the server hosting the
* database server application. In case of serverless database
* implementations like SQLite it's the directory path where the database
* file is located. The path must contain the platform specific path
* separators like slash ("/") on Unix-like systems and backslash ("\")
* on Windows systems. Also the path must end with the path separator
* like "/path/to/file/".
*
* Furthermore \a port can be the number or name the database server
* application is listening to. If a name instead of the number is
* allowed depends on the database client library but the number as
* string does always work. If an empty string is given, the default
* port of the database server application is used by the database
* client library.
*
* @param backend Name of the backend module to use
* @param host Name or IP address of the database server
* @param port Name or number of the port used by the database server
* @return Connection instance
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see #Conn( const char*, const char*, const char* )
*/
Conn( const string& backend, const string& host = "", const string& port = "" ) throw( std::exception );
/**
* Destroys the connection instance if no other references exist.
*
* Each connection object uses a reference counter to remember if the
* connection is shared with other objects. If this isn't the case or
* if this object is the last one referencing the connection, the
* connection is closed and the allocated memory is freed.
*/
~Conn() throw();
/**
* Copy constructor.
*
* Enables the transfer of the internal state of an object \a ref of the same
* type to this object. Both objects share the same database connection
* and the reference counter afterwards. The reference counter is
* incremented each time an object is copied and will be decremented if
* it is destroyed.
*
* @param ref Original connection object instance
*/
Conn( const Conn& ref ) throw();
/**
* Assigns a connection instance to another one.
*
* Assigns the internal state of an object \a ref of the same type to this
* object. Both objects share the same database connection and the
* reference counter afterwards. The reference counter is incremented
* each time an object is copied and will be decremented if it is
* destroyed.
*
* @param ref Connection instance
* @return Connection reference of this instance
*/
Conn& operator=( const Conn& ref ) throw();
/**
* Authenticates the user and selects the database using C style string
* parameters.
*
* After initializing the object instance with one of the constructors
* taking a backend, host and port string as parameter, it's necessary
* to authenticate the user and select a database. Depending on the
* database client library, it also establishes the connection to the
* database server. This method accepts C style strings for the database
* name, the user name and the password.
*
* The first parameter, the name of the database will be used to select
* the database all further commands are operating on. The database is
* the container for the tables, views, etc., which store the records
* and provide access to them.
*
* Authentication is done in most cases by a combination of a user name
* and a password. If the user name is known by the database server and
* the supplied password matches with the stored one, the database
* server will allow the user to operate on the selected database and
* its tables provided the user has permissions to read and/or modify
* the content.
*
* The \a method parameter can be used to select different methods of
* authentication. At the moment, only simple authentication
* (ODBX_BIND_SIMPLE) with user name and password is available.
*
* @param database Name of the database managed by the database server
* @param who Name of the user account known by the database server
* @param cred Necessary credential which belongs to the user account
* @param method Method used for authentication
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void bind( const char* database, const char* who = "", const char* cred = "", odbxbind method = ODBX_BIND_SIMPLE ) throw( std::exception );
/**
* Authenticates the user and selects the database using C++ style string
* parameters.
*
* After initializing the object instance with one of the constructors
* taking a backend, host and port string as parameter, it's necessary
* to authenticate the user and select a database. Depending on the
* database client library, it also establishes the connection to the
* database server. This method accepts C++ style strings for the
* database name, the user name and the password.
*
* The first parameter, the name of the database will be used to select
* the database all further commands are operating on. The database is
* the container for the tables, views, etc., which store the records
* and provide access to them.
*
* Authentication is done in most cases by a combination of a user name
* and a password. If the user name is known by the database server and
* the supplied password matches with the stored one, the database
* server will allow the user to operate on the selected database and
* its tables provided the user has permissions to read and/or modify
* the content.
*
* The \a method parameter can be used to select different methods of
* authentication. At the moment, only simple authentication
* (ODBX_BIND_SIMPLE) with user name and password is available.
*
* @param database Name of the database managed by the database server
* @param who Name of the user account known by the database server
* @param cred Necessary credential which belongs to the user account
* @param method Method used for authentication
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void bind( const string& database, const string& who = "", const string& cred = "", odbxbind method = ODBX_BIND_SIMPLE ) throw( std::exception );
/**
* Releases the connection to the database and resets the authentication
* status.
*
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void unbind() throw( std::exception );
/**
* Cleans up the connection object.
*
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void finish() throw( std::exception );
/**
* Tests if the database driver module does understand certain extensions.
*
* The OpenDBX library consists of a basic set of functions that must be
* implemented by all drivers and optional sets for additional
* functionality. This method allows an application to ask the driver
* selected by the first parameter of the constructor of this object if
* it supports one or more optional sets. The available sets and its
* constants are:
*
* - ODBX_CAP_BASIC\n
* The core function set which have to be implemented by all backends.
* It consists of all functions necessary to connect to, send textual
* queries to and process simple results returned from the database
* server as well as error handling functions.
* - ODBX_CAP_LO\n
* The function set for handling large objects whose content isn't
* accessible by the basic function. Currently, Firebird/Interbase
* and Oracle requires using the LOB functions.
*
* The basic set makes sure that all drivers can handle connections to
* the databases, send statements and retrieve results. It's supported
* by all drivers and usually don't have to be checked.
*
* Some databases client libraries provide the content of large objects
* not via the basic functions. Instead, the Result::fieldValue() method
* returns only a handle to the large object and reading or modifying
* the content of this data object requires calling additional methods.
*
* @param cap Constant of the capability
* @return True if supported, false if not
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
bool getCapability( odbxcap cap ) throw( std::exception );
/**
* Gets the value of a certain option provided by the database driver module.
*
* It asks the backend module for implemented options and their current
* values. This function can be used at every stage and its primary use
* is to find out supported features of the backend module. This features
* can be enable with setOption() before the connection to the database
* server is established by calling bind().
*
* There are several option values defined as named constants in the
* opendbx/api.h header file. A few of them are for informational purpose
* only while most of the options can also be set to different values
* by setOption() to change the behavior of the backend module. These
* options are:
*
* - ODBX_OPT_API_VERSION\n
* The API version implemented by the backend. It returns a five digit
* number representing the API version of the backend module in the
* form XYYZZ where X is the major number, YY the revision and ZZ the
* minor number of the API.
* - ODBX_OPT_THREAD_SAFE\n
* If it is safe to use this backend and especially the native database
* client library in an application which uses threads where more than
* one thread opens database connections via the OpenDBX library.
* - ODBX_OPT_TLS\n
* The database client library may support transmitting all data
* securely by encrypting the network traffic via SSL or TLS.
* - ODBX_OPT_MULTI_STATEMENTS\n
* The database server may be able to support multiple SQL statements
* in one string sent to the database.
* - ODBX_OPT_PAGED_RESULTS\n
* All database servers and client libraries are able to transfer the
* records row by row. Some of them can also transfer multiple rows
* or even all at once to minimize server load, network traffic and
* latency. The downside of this is an increased memory consumption.
* - ODBX_OPT_COMPRESS\n
* Support of compressed network traffic between database client and
* server. This can lead to higher throughput if the network is the
* bottleneck.
* - ODBX_OPT_MODE\n
* Some database servers support different modes of operation, e.g.
* modes for compliance to other SQL implementations or completely
* different query languages.
*
* The parameter \a value must be a pointer to an integer variable where
* the backend module will store the result for the supplied option. If
* it's not stated otherwise, the value assigned to the this parameter
* will be of boolean nature and therefore is ODBX_ENABLE for a supported
* option or ODBX_DISABLE for an option which isn't supported.
*
* @param option Constant of the option
* @param value Pointer to memory where the result is stored
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void getOption( odbxopt option, void* value ) throw( std::exception );
/**
* Sets a certain option provided by the database driver module.
*
* Changes the value of the specified option in the backend module or
* the native database library. Before trying to set an option, it should
* be tested with getOption() first to ensure that it is supported by
* the backend. Almost all options need to be set before connecting to
* the database server using bind() to take any effect.
*
* There are several option values defined as named constants in the
* opendbx/api.h header file. The possible options are:
*
* - ODBX_OPT_TLS\n
* Use encryption to transmit all data securely over the network via
* SSL or TLS. This option can be set to ODBX_TLS_NEVER (the default
* value) to prevent encrpytion, ODBX_TLS_ALWAYS to enforce encryption
* and to fail if it can't be used between the client library and the
* server or ODBX_TLS_TRY to use encryption if possible with the
* option to fall back to a connection which isn't encrypted.
* - ODBX_OPT_MULTI_STATEMENTS\n
* Enables the database server to accept multiple statements in one
* string to the database if the value of value is set to ODBX_ENABLE.
* Although, it might be possible to disable it by setting it to
* ODBX_DISABLE.
* - ODBX_OPT_PAGED_RESULTS\n
* All database servers and client libraries are able to transfer the
* records row by row. Some of them can also transfer multiple rows
* or even all at once to minimize server load, network traffic and
* latency. The downside of this is an increased memory consumption.
* If paged results are supported by the backend, passing positive
* values will fetch the specified number of records at once from the
* database server. The value of zero ("0") is special in this case
* because it asks the backend module to retrieve all records at once.
* - ODBX_OPT_COMPRESS\n
* Enable compressed network traffic between database client and
* server. This can maximize the throughput if the network is the
* bottleneck. Pass an integer variable with ODBX_ENABLE to enable
* compression or with ODBX_DISABLE to disable it for this connection.
* - ODBX_OPT_MODE\n
* Some database servers support different modes of operation, e.g.
* modes for compliance to other SQL implementations or completely
* different query languages. The value for this option must point to
* a zero terminated string.
*
* If not stated otherwise, the type of the variable passed to the second
* parameter named \a value must be an integer pointer. Its values
* must be in the range specified by the option being changed.
*
* @param option Constant of the option
* @param value Pointer to memory which contains the new value
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
void setOption( odbxopt option, void* value ) throw( std::exception );
/**
* Escapes potentially dangerous characters in user input using a C style buffer.
*
* For preventing SQL injection attacks which can have desasterous
* effects, all text input that will be part of an SQL statement must be
* escaped. This does also apply to user content that is already stored
* in the database and should be copied to another record or stored
* again as the escaping is removed before the database server writes
* the content to disk.
*
* The first parameter must contain the character sequence that should
* be escaped as C style string. This string itself won't be modified
* by this method.
*
* The escaped string will be written to the third parameter named
* \a to, which have to be also an C++ style string. After transforming
* the input to an escaped string, the result may be more then twice
* the size of the original input. The additional escape sequences
* aren't stored in the database column so only the original string will
* be written to the disk.
*
* A C++ reference of the third parameter containing the escaped string
* afterwards is also returned by this method to providing the possibility
* to write more elegant code.
*
* @param from Input string with which may contain dangerous characters
* @param fromlen Size of the input string to escape in bytes
* @param to String instance where the escaped characters should be written to
* @return Reference to the second parameter containing the escaped characters
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
string& escape( const char* from, unsigned long fromlen, string& to ) throw( std::exception );
/**
* Escapes potentially dangerous characters in user input using a C++
* style string parameter.
*
* For preventing SQL injection attacks which can have desasterous
* effects, all text input that will be part of an SQL statement must be
* escaped. This does also apply to user content that is already stored
* in the database and should be copied to another record or stored
* again as the escaping is removed before the database server writes
* the content to disk.
*
* The first parameter must contain the character sequence that should
* be escaped as C++ style string. This string itself won't be modified
* by this method.
*
* The escaped string will be written to the third parameter named
* \a to, which have to be also an C++ style string. After transforming
* the input to an escaped string, the result may be more then twice
* the size of the original input. The additional escape sequences
* aren't stored in the database column so only the original string will
* be written to the disk.
*
* A C++ reference of the second parameter containing the escaped string
* afterwards is also returned by this method too, providing the possibility
* to write more elegant code.
*
* @param from Input string with which may contain dangerous characters
* @param to String instance where the escaped characters should be written to
* @return Reference to the second parameter containing the escaped characters
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
*/
string& escape( const string& from, string& to ) throw( std::exception );
/**
* Creates a statement object from a SQL text string using a C style buffer.
*
* This method returns an instance of the Stmt class that contains the
* statement sent to the database server later on. Currently, only simple
* statements are supported, which are sent to the database server for
* parsing and returning the result after calling Stmt::execute(). Later
* on also prepared statements will be possible which are parsed by the
* database server when creating the object and only the parameters
* will be sent to the database server on execution. This can speed up
* processing especially if the statement is executed multiple times
* with different content for the parameters.
*
* The parameter named \a sql must contain the SQL text string that should be
* sent to the database server for execution. It have to be a C style
* buffer in this case. For a reference of valid SQL statements, please
* have a look at the documentation of your database server.
*
* The length of the statement excluding the trailing "0" byte should
* be given via the second parameter \a size. If the length of the statement is
* unknown, you can also supply zero (0) as size value which is also the
* default value if you hand over only one parameter. In this case, the
* length of the string is calculated internally by this function before
* the statement is given to the native database library.
*
* Via the last parameter it can be selected how the statement should
* be treated internally by the OpenDBX and the native database library.
* Currently, only simple processing is available which sends complete
* SQL statements including its parameters as string to the database
* server for parsing and execution. Later on, also prepared statement
* handling will be available which parses the statements first and
* sends only the parameters to the server before execution. This
* parameter is also optional.
*
* The returned object is representing the given statement, which can
* be executed later on. The statement is only valid for the current
* connection and as soon as the connection gets invalid or is closed,
* working with this object will throw an error.
*
* @param sql SQL text string containing a valid statement understood by the database server
* @param size Size of the SQL text string in bytes
* @param type Type of statement object that should be created
* @return Statement instance bound to this connection
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see Stmt
*/
Stmt create( const char* sql, unsigned long size = 0, Stmt::Type type = Stmt::Simple ) throw( std::exception );
/**
* Creates a statement object from a SQL text string using a C++ string.
*
* This method returns an instance of the Stmt class that contains the
* statement sent to the database server later on. Currently, only simple
* statements are supported, which are sent to the database server for
* parsing and returning the result after calling Stmt::execute(). Later
* on also prepared statements will be possible which are parsed by the
* database server when creating the object and only the parameters
* will be sent to the database server on execution. This can speed up
* processing especially if the statement is executed multiple times
* with different content for the parameters.
*
* The parameter named \a sql must contain the SQL text string that should be
* sent to the database server for execution. It have to be a C++ style
* string in this case. For a reference of valid SQL statements, please
* have a look at the documentation of your database server.
*
* Via the last parameter \a type it can be selected how the statement should
* be treated internally by the OpenDBX and the native database library.
* Currently, only simple processing is available which sends complete
* SQL statements including its parameters as string to the database
* server for parsing and execution. Later on, also prepared statement
* handling will be available which parses the statements first and
* sends only the parameters to the server before execution. This
* parameter is also optional.
*
* The returned object is representing the given statement, which can
* be executed later on. The statement is only valid for the current
* connection and as soon as the connection gets invalid or is closed,
* working with this object will throw an error.
*
* @param sql SQL text string containing a valid statement understood by the database server
* @param type Type of statement object that should be created
* @return Statement instance bound to this connection
* @throws std::invalid_argument If the object was only initialized by the default constructor
* @throws OpenDBX::Exception If the underlying database library returns an error
* @see Stmt
*/
Stmt create( const string& sql, Stmt::Type type = Stmt::Simple ) throw( std::exception );
};
} // namespace OpenDBX
} // extern C++
#endif
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