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ClearSelectedRow - cWebGrid

Performs a DD Clear operation, clearing any changes in the current row and restoring it to its unchanged state

Type: Function
Return Data Type: Integer

Syntax

Function ClearSelectedRow Returns Integer

Call Example

Get ClearSelectedRow to IntegerVariable

Description

ClearSelectedRow performs a clear operation by resetting the row back to its original unchanged state. If clearing may cause data-loss a data loss verification message may be sent. This message is only sent if the DataDictionary object (DDO) is changed and the data entry object's (DEO's) Verify_Data_Loss_msg is set. This operation is performed using the RequestClearExec message as described below.

RequestClearExec - Request messages and user verifications with web objects

When the browser client selects a save, delete, clear or clear-all the message Request_Save, Request_Delete, Request_Clear or Request_Clear_All is sent to the server. These do a traditional DataFlex style request operation which is validation, verification and then the actual DD operation (Request_Save, Request_Delete, Clear, Clear_All). A verification is required based on the contents of Verify_Save_msg, Verify_Delete_msg and Verify_Data_Loss_msg. If a verification is required, the client needs to get involved to perform the user verification. This means that the operation requires an additional round trip. If the verification is accepted by the user, a message is sent to the server which handles part two of the request. Those part two messages are RequestSaveExec, RequestDeleteExec, RequestClearExec and RequestClearAllExec. These are the messages that attempt to actually perform the requested DD operation. You can think of these as "pre" and "post" messages.

If the verify messages are 0, which means that a user confirmation is not needed, the "pre" message (e.g. ClearSelectedRow) will directly send the "post" message (e.g. RequestClearExec) without requiring an additional trip to the client.

Here is a rough outline of what happens with a ClearSelectedRow.

ClearSelectedRow     If no changes return     If Verify_Data_Loss_msg exists, tell the client to present the verification and make a callback *     Else Send RequestClearExec

RequestClearExec     If Row has a Record         Refind the record in the DDO and update the Grid Row     else         Send Clear to the DDO, which will clear the Grid Row

  • If the user confirms the operation, the client will make another server request which will indirectly send RequestClearExec

If you need to make a save, delete, clear, clear_all request manually (e.g., within a cWebButton) you should use Request_Save, Request_Delete, Request_Clear and Request_Clear_All and not these "exec" messages.

If you are augmenting these requests you need to be careful as they occur in two steps and it is possible that the second step (the exec) may not get called at all. Notice that the "pre" message (e.g., ClearSelectedRow) may have actually performed the entire operation (if there is no verify message) or may have merely launched the operation which might be completed during the next server "post" request (e.g. RequestClearExec).

Return Value

Returns True if the clear was successful.