borland Packages Class Hierarchy dx.dataset Package
java.lang.Object +----com.borland.dx.dataset.Provider +----com.borland.dx.sql.dataset.DataModelProvider +----com.borland.dx.sql.dataset.JdbcProvider
Properties Methods
Implements Designable, Serializable
The Provider class is an abstract base class that "provides" (or populates) a DataSet with data. Extend this class if you want to create a custom provider. The instantiable subclasses (technically, subclasses of its JDBCProvider subclass) QueryProvider and ProcedureProvider are included. These classes collect provider functionality using queries and stored procedures on JBDC data sources.
public boolean isAccumulateResults()Return false if new data provide requests should empty the associated StorageDataSet. Return true if new data provide requests should leave existing rows in the associated StorageDataSet.
public ReadWriteRow getParameterRow() public void setParameterRow(ReadWriteRow value)This is the parameterRow that will be used by extensions of StorageDataSet, like QueryDataSet and ProcedureDataSet, to fill in parameter values for parameterized queries or stored procedures. If a TableDataSet extension of StorageDataSet has a QueryProvider or ProcedureProvider, this property will also be used by those providers to fill in parameter values for parameterized queries or stored procedures.
public void checkIfBusy(StorageDataSet dataSet)Some implementations of the provideData method may optionally provide the data asynchronously. A StorageDataSet has to block actions such as resolving until the asynchronous data is present. This method allows an implementation to give an appropriate error message by raising a DataSetException. The default action is to do nothing, i.e. no asynchronous providing.
public void checkMasterLink(StorageDataSet dataSet, MasterLinkDescriptor masterLink)Called to validate the masterLink property. When the MasterLinkDescriptor's fetchAsNeeded property is enabled (true), the QueryProvider uses this method to check if there is a WHERE clause in the query. If no WHERE clause is specified, the QueryProvider throws a DataSetException.
public void close(StorageDataSet dataSet, boolean loadRemainingRows)Releases resources kept for loading data on demand. StorageDataSet calls this method when the storage is being closed and when calling StorageDataSet.closeProvider. The loadRemainingRows parameter controls whether the rest of the data (if more data is available) is loaded or not.
public boolean hasMoreData(StorageDataSet dataSet)Some implementations of a Provider may allow to provide part of the data, then load more data on demand. This method should return true if there is more data to be loaded. To load the data, call the provideMoreData method.
public abstract void provideData(StorageDataSet dataSet, boolean toOpen)Provides the data for a DataSet. The source of the data, and the method of retrieving the data is up to the implementation of this abstract method. The toOpen parameter indicates whether this method is called as part of opening this StorageDataSet.
public void provideMoreData(StorageDataSet dataSet)Some implementations of a Provider may allow to provide part of the data and then load more data on demand. This method provides more data if there is more data to be loaded. If no more data is available, this method simply returns.