如何在 TDataSet.UpdateRecord 中捕获错误？

Question

My application uses a QuantumGrid (v6.56) and a TSimpleDataSet as its data source.

Problem: an exception is thrown if the user enters a non-numeric value in aa numeric field. The code does not reach the OnBeforePost handler.

How can the application catch the error (and display a message to the user), if the exception is thrown before OnBeforePost?

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Stack trace:

exception class   : EDatabaseError
exception message : '...' is not valid Integer value for Field <somefieldname> 

main thread ($504):
00526c7e +082 EditBooking.exe DB                               DatabaseError
00526d0f +04b EditBooking.exe DB                               DatabaseErrorFmt
0052c428 +07c EditBooking.exe DB                               TIntegerField.SetAsString
0052af30 +00c EditBooking.exe DB                               TField.SetText
0052abf9 +021 EditBooking.exe DB                               TField.SetEditText
007c3a3f +053 EditBooking.exe cxDBData                           
007e14a8 +018 EditBooking.exe cxGridDBDataDefinitions          TcxGridDBDataController.UpdateData
006f8159 +039 EditBooking.exe cxCustomData                     TcxCustomDataProvider.DoUpdateData
007c1c18 +008 EditBooking.exe cxDBData                         TcxDBDataLink.UpdateData
0053325d +021 EditBooking.exe DB                               TDataLink.UpdateRecord
005333f8 +0d8 EditBooking.exe DB                               TDataLink.DataEvent
007c1683 +00f EditBooking.exe cxDBData                         TcxDBDataLink.DataEvent
00533973 +03f EditBooking.exe DB                               TDataSource.NotifyLinkTypes
005339a2 +01e EditBooking.exe DB                               TDataSource.NotifyDataLinks
005339cf +023 EditBooking.exe DB                               TDataSource.DataEvent
005392ad +131 EditBooking.exe DB                               TDataSet.DataEvent
00553d7c +058 EditBooking.exe DBClient                         TCustomClientDataSet.DataEvent
00539396 +042 EditBooking.exe DB                               TDataSet.UpdateRecord
0053a356 +006 EditBooking.exe DB                               TDataSet.Post
0055677c +054 EditBooking.exe DBClient                         TCustomClientDataSet.Post

Answer 1

You need to set the "Properties" property of your column in the cxGrid, there you can assign a CurrencyEdit so the user can only enter numbers, also after setting "Properties" you can use the OnValidate event to validate the user entry.

Answer 2

In your example, the event OnBeforePost isn't reached indeed.

You mention the cxGrid, but the fact is, your issue is easy to reproduce.

Take a simple TDBEdit linked on a TFloatField and try to enter the value "7.7.7.7.7.7.7.7". Float fields accept the decimal separator, but won't validate that only 1 is present. So entering this will also result in an error being raised in a similar fashion, either when you exit the field, or while posting, if you have a shortcut that allows you to do so.

If you want to intercept it "on the way in", then TField.OnSetText is probably your best bet.