Edit records of a field clientdataset from a Join

Question

I have a simple example, but in three layers, with sqldataset + datasetprovider + clientdataset. I do not load any field in sqldataset. In datasetprovider I leave the updatemode in upwherekeyonly.

In datasetprovider I leave allowcommandtext as true to be able to receive client-side commandtext via clientdataset. On the client side I load the Fields with Select * ... and during the run time I send the commandtext with a Join so that it brings only the fields already loaded. When I try to edit some record and give applyupdates in onreconcileerror event I get:

Unable to Find Record. No Key especified

Use xe5+dbexpress+mysql. The question is how do I configure components to edit and update records coming from a command with Join?

SUMMING UP THE DISCUSSION

You can leave all the default settings of Delphi, the only thing you need is to put in the event Ongettablename of the datasetprovider the name of the table to be updated, this solved all my problems.

Answer 1

Artur, this happens because for Dataset understands that all fields belong to the same table.

To fix the problem, you must configure which fields are not table data fields, which key and which table to update.

Properly configure the fields

One way to do this is by setting the property Providerflags to empty, saying that the field should not appear either in the Where nor be updated (pfInWhere, pfInUpdate).

CampoA.ProviderFlags := [];

Or by changing the Fieldkind for fkInternalCalc.

CampoA.FieldKind := fkInternalCalc;

Another important thing is to define the primary key field, to ensure that the Precedent correctly identifies the key to be used, and for this you must set the Providerflag for pfInKey

CampoChave.ProviderFlags := CampoChave.ProviderFlags + [pfInKey];

or Field.Providerflags := [pfInUpdate, pfInKey];

Set the name of the table to be updated

In addition, it is recommended to implement the event onGetTableName of Tdatasetprovider, so that he knows which table to update.

procedure DataSetProvider.onGetTableName(Sender: TObject);
begin
    Result := 'NomeDaTabelaASerAtualizada';
end;