Guide to the Visual FoxPro CursorAdaptor
The document is now available online.
Visual FoxPro has excellent facilities for database application development utilising a client-server database management system to store data as a replacement for the native FoxPro table files. The advantages of this approach are too numerous to mention here and there are various FoxPro features available to the developer requiring access to client-server data:
- Remote Views created in a database container to reference a client server database query representing retrieved data as a cursor.
- Parameterised Remote Views that limit the amount of data retrieved from the server.
- SQL pass-through queries that allow commands to be executed directly on the database server with the results returned as a cursor.
- Table buffering and commit and rollback commands to control the timing of updates sent to the database server.
- Connection control allowing performance optimisation, asynchronous queries, and so forth.
These features have been available since version 3.0 of Visual FoxPro and are now supplemented with the CursorAdapter class (first available with FoxPro 8.0) that allows an object-oriented software object that accesses client-server data in a flexible manner. Some notable features include:
- Transparent definition of native FoxPro or client-server database offering the best way to migrate an existing application to client-server.
- Seamless integration with ADO and XML.
- Manipulation of an extensive range of properties compatible with existing remote views and connection properties.
- Integration into the data environment of a form.
- Event driven model allowing sophisticated client-side validation and processing.
This document complements the redware Visual FoxPro Client-Server Handbook which describes in detail the techniques and optimisations to access client-server databases using all the available features of Visual FoxPro through to version 7.0. The use of the CursorAdapter object is discussed in detail with regards to accessing client-server data (ADO and XML interfaces are not covered here).
If you are not familiar with making connections to client-server databases and the use of table buffering with Visual FoxPro you will need further study or purchase of the redware FoxPro SQL Server Handbook (available from www.redware.com). Optimisation features are also not covered in this document which will be integrated into the next edition of the Handbook.
The document is 16 pages long with the following headings and is available online:
- Setup Table Buffering
- Use Parameters to Filter Data
- Fill a CursorAdapter using a Stored Procedure
- Update Data
- Save a CursorAdapter as a Visual Class
- Use the CursorAdapter Event Model for Data Validation
- Overcome the Property Length Problem in a Visual Class
- Attach an Existing Cursor.
- Create a Cursor with the CursorAdapter Builder
- Build a CursorAdapter with cabuilder.prg