How to use TDataSet.DisableControls with Master/Detail datasets?

Question

Calling TDataSet.DisableControls disables the link between master/detail datasets. Is there another way to disable updating data-aware controls without affecting the master/detail relationship? I know I can set individual component's DataSource to nil, but this isn't the practical way for me.

score 2 · Accepted Answer · answered Sep 01 '12 at 15:09

2

This solution presumes you use separate TDataSource instances for linking UI controls and for Master-Detail relations which - from a design perspective - is a good idea anyway.

The drawback of this solution: this cause some flickering in your UI.

You could:

Enumerate all TDataSource instances that point to your TDataSet instances but are not involved in Master-Detail relations.
For each of those instances, save the Enabled property.
For each of those instances, set the Enabled property to False
Run your logic
For each of those instances, restore the Enabled property.

answered Sep 01 '12 at 15:09

Jeroen Wiert Pluimers

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Seems like a good idea to write a class which can enumerate datasources and maintain these links. Then instantiate an instance per data module that needs such management tasks. – Warren P Sep 01 '12 at 16:31
Neat idea, but not practical in my case. I have a database action which duplicates the current record of associated dataset, with all of the corresponding detail records. I have no idea if the user has twin datasources per dataset or not. – iMan Biglari Sep 02 '12 at 06:26
Duplication of data usually is not such a good idea. Why do you need that? – Jeroen Wiert Pluimers Sep 03 '12 at 09:37

score 1 · Answer 2 · answered Feb 04 '19 at 05:36

Nowadays you have a perfect option to achieve this. As the Delphi Help states:

If the dataset is the master of a master/detail relationship, calling DisableControls also disables the master/detail relationship. Setting BlockReadSize instead of calling DisableControls updates the detail datasets as you scroll through the dataset, but does not update data-aware controls.

How to use TDataSet.DisableControls with Master/Detail datasets?

2 Answers2