Remarks

This method try to establish a connection to a data store. It returns True (.T.) if connection is established. otherwise it returns False (.F.), in such case, the Errors collection contains detailed information on what went wrong.

Before attempting to connect to a data store, the Session.BeforeConnect event is fired. If this event returns a True value (.T.) connection attempt continues, otherwise connection is aborted and Session.Connect returns False.

In order to connect to a data store, Session.Connect uses a DataSource object. A datasource object is an object instance of one of the fdoDataSource subclasses provided with FDO that supplies all the information needed to establish a connection. For a complete reference on DataSources please see the fdoDataSource class reference.

A DataSource object can be passed as a parameter to the Session.Connect method. When no datasource object has been received, Session.Connect will check the Session.DataSourceLookupMode property to know how to search for a valid datasource object to use for the connection.

The next table summarizes the DataSourceLookupMode values:

If no valid datasource object is found, Session.Connect returns False.

Once Session.Connect has a valid DataSource object, the DataSource.AccessType property instructs the persistence engine either to connect to a Visual FoxPro native Database (direct file access to DBC file) or to connect to a remote data store by using ODBC.

If the datasource object AccessType is 1 (ODBC), Session.Connect gets the ODBC connection string from the datasource object by calling the DataSource.GetConnectionString method, and tries to connect via the SqlStringConnect VFP function. Except when the DataSource.ODBC_ConnectionHandlerSuppliedByClient values is .T., where Session.Connect skips the whole connection procedure and uses an existing ODBC handler value previously stored on Session.ODBC_ConnectionHandler.

The datasource object used for connection is stored on the Session.DataSource property and is later used for automatic reconnections.

If connection succeeds, then Session.AfterConnected event fires, otherwise, the Session.AfterConnectionFailure event fires.

Session.Connect returns .T. if connection succeeds or false if connection fails.

SET PROCEDURE TO FDO ADDITIVE
oServer=CREATEOBJECT("fdoServer")
 

oServer.ConnectedSessionsOnly=.F.
 

oSession = oServer.NewSession("MyApp.fdo")

oDS=oServer.NewDataSource("MySQL")
oDS.Database_Name=”Contacts”
oDS.ODBC_SRV="192.168.0.5"
oDS.ODBC_PORT=3307

IF oSession.Connect(oDS)

   IF oSession.EnsureDatabaseStatus(4)

      ? "Session connected, database selected and database schema is UpToDate"

   ELSE

      oSession.Disconnect

      ? "Session disconnected. Database schema is out of date and update failed."

      ? oSession.Errors.ToString()

   ENDIF

ELSE

   ? "Cannot connect to datasource"

   ? oSession.Errors.ToString()

ENDIF

The Session.Connect method is called with the datasource object passed as a parameter.

If connection succeed, the Session.EnsureDataBaseStatus method will open the connection, check for the database, select the database and check for database schema version. If necessary, it will upgrade the database schema. (Note the CheckLevelStatus passed as a parameter is 4 CHECK_DBINUSEANDTABLESUPTODATE ). In case the database schema cannot be upgraded, the connection is closed using Session.Disconnect.

SET PROCEDURE TO fdo ADDITIVE

oServer=CREATEOBJECT("fdoServer")

oServer.ConnectedSessionsOnly=.F.

oSession=oServer.NewSession("MyMappingSchema.FDO")

oDataSource=oServer.NewDataSource("MsSQLServer")

oDataSource.ODBC_ConnectionHandlerSuppliedByClient=.T.

oSession.ODBC_ConnectionHandler=nConn

IF oSession.Connect(oDataSource)

   ? "ODBC Handler",oSession.ODBC_ConnectionHandler

   oSession.Disconnect

ENDIF

This sample creates a DataSource object for Ms SQL Server, connects using an existing ODBC connection handler stored on nConn.
 

See Also