TClientBlobStream Class

TClientBlobStream lets applications read from or write to BLOB fields in a client dataset.

Pascal

TClientBlobStream = class(TMemoryStream);

C++

class TClientBlobStream : public TMemoryStream;

File

DBClient

Description

Use TClientBlobStream to access or modify the value of a Binary Large Object (BLOB) field in a client dataset. BLOB fields are TBlobField objects and descendants of TBlobField such as TGraphicField and TMemoField. BLOB fields in client datasets use client BLOB streams to implement many of their data access properties and methods.

TClientBlobStream allows objects that have no specialized knowledge of how data is stored in a BLOB field to read or write such data by employing the uniform stream interface.

To use a client BLOB stream, create an instance of TClientBlobStream, use the methods of the stream to read or write the data, and then free the BLOB stream. Do not use the same instance of TClientBlobStream to access data from more than one record. Instead, create a new TClientBlobStream object every time you need to read or write BLOB data on a new record.

Note: Explicitly creating a TClientBlobStream instance does not ensure that the current record has fetched its BLOB data. To ensure that the BLOB field contains its data before reading from the BLOB stream, call the client dataset's FetchBlobs method before creating the BLOB stream or use the client dataset's CreateBlobStream method to create the BLOB stream indirectly.