FireDAC ApplyUpdates和事务控制

Question

I am converting application written in DBExpress to use new FireDAC components. The basic things like opening the query, changing filter or ordering, displaying in grid are working correctly. But I am surprised that some functions behave differently in comparison to dbexpress and I cant seem to comprehend it.

My application contains database editor. When user opens the editor new transaction is started by calling method TFDConnection::StartTransaction . When the user clicks on OK button, the active transaction is committed and editor closes.

In editor I use two queries to edit records. In first query I manually compose SQL update command (like " update TEST set NAME='some name' where ID=1234 ") and execute it. So far so good.

Second query is connected to TDBAdvGrid (equivalent of TDBGrid from TMS Software company ) and have CachedUpdates = true . If I change some record in that grid I call TFDQuery::Post and TFDQuery::ApplyUpdates .

Whats weird calling TFDQuery::ApplyUpdates commits not only pending changes in this specific query, but all queries connected to instance of TFDConnection . I thought that calling of ApplyUpdates should issue SQL update calls but should not interfere with transaction control.

I want to give the user option to reject all changes made by him in database editor window. How to do it correctly ? Should I postpone call to ApplyUpdates to time when closing window ? What is then the purpose of TFDQuery::CommitUpdates and TFDConnection::Commit if all that is necessary is the call of TFDQuery::ApplyUpdates ?

Answer 1

Set TFDConnection::TxOptions::StopOptions::xoIfCmdsInactive to false. This will also disable TFDConnection::TxOptions::AutoCommit option and application can controls transactions by itself.