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====== EditTables - Deleting and Inserting Rows ======

=== Published 20 APR 2018 at 10:52:00AM ===

Support for deleting and inserting rows in the EditTable control has always been somewhat basic, exposing only minimum functionality that allows you to control how a user inserts or deletes a row in the grid.  We've enhanced this for version 10 by providing some fine-grain control over the row insertion and deletion process that we'll describe below.

====  ====

==== Imposing limits ====

Firstly, a couple of new properties have been implemented that allow you to set limits on the number of rows a user can add or remove from the EditTable via the keyboard: These are the **MAXROWLIMIT** and **MINROWLIMIT** properties.

=== MAXROWLIMIT property ===

When **MAXROWLIMIT** is set the user cannot use the Insert key to insert more rows than the number specified by this property.  The default value is "0", which means there is no maximum limit.   Note that this property does not apply to programmatic **INSERT** method operations or data set by the **LIST** or **ARRAY** properties.

=== MINROWLIMIT property ===

When **MINROWLIMIT** is set the user cannot use the Delete key to delete EditTable rows once the minimum limit has been reached. The default value is "0", which means there is no minimum row limit.   Note that this property does not apply to programmatic **DELETE** method operations or data set by the **LIST** or **ARRAY** properties.

====  ====

==== Blocking the "Insert" and "Delete" keys ====

Previous versions of the EditTable allowed you to set a "Protected" property at design time that stopped all row insert //and// delete operations by the user.  Unfortunately, this was not actually exposed run-time (unless you adjusted a bit-flag the control's **STYLE** property), so in version 10 we've expanded the old "Protected" property into two new properties called **ALLOWROWDELETE **and **ALLOWROWINSERT**.  These can used at both run-time and design-time.

=== ALLOWROWDELETE property ===

When set to False the user cannot use the Delete key to delete rows within an edit table.  The default value of this property is True.

=== ALLOWROWINSERT property ===

When set to False the user cannot use the Insert key to insert new rows within an edit table.  The default value of this property is True.

====  ====

==== Managing the "Insert" and "Delete" keys ====

Finally, we made some changes to the way the actual inserts and deletes take place to give you an opportunity to intercept them for even more control.  In previous versions of OpenInsight the EditTable notified you of an insert or delete operation //after// it had taken place, via the **INSERTROW** and **DELETEROW** events respectively.  This means that if you wanted to 'prevent' the modification based on some run-time criteria you had to effectively undo it, which usually included some sort of unpleasant visual effect as the insert or delete was rolled back (it also resulted in a loss of formatting information or other cell-specific data that you would have to reapply). In version 10 we've added a new Boolean property called **ROWEVENTMODE**. When set to False (the default) row insertion and deletion via the keyboard behaves in exactly the same way as previous versions of OpenInsight.  When set to True however, the **INSERTROW** or **DELETEROW** event happens //before// the actual operation takes place, and at this point you can do the following:

  - If you're using an EventScript you can return FALSE$ and the operation will be cancelled.
  - If you're using a code called from a QuickEvent you can set the EventStatus flag in your code to prevent the operation from proceeding further, just as you would currently do in a **WINDOW** **CLOSE** event to cancel it.

  E.g. Stopping a row being deleted in a **DELETEROW** EventScript handler.

<code>
// Assumes "RowEventMode" is "True" 
//
// Check to see if there is anything in column 2 of the deleted data,
// and if so stop the delete via the event return value. 

$insert logical
if bLen( rowData<2> ) then
   // Stop the delete
   retVal = FALSE$
end else
   retVal = TRUE$
end

return retVal
</code>

  E.g. Stopping a row being deleted in a **DELETEROW** QuickEvent handler

<code>
// Assumes "RowEventMode" is "True" 
//
// Check to see if there is anything in column 2 of the deleted data,
// and if so stop the delete via the Event Status 

$insert logical 
if bLen( rowData<2> ) then
   // Stop the delete
   call set_EventStatus( TRUE$ )
end

return
</code>

Of course, once you've allowed the Insert or Delete operation to take place you may also want to do some post-processing, and for this we've provided two new events: **INSERTEDROW** and **DELETEDROW**.  These have the same signature as their **INSERTROW** and **DELETEROW** counterparts and are executed after the row modification has taken place (Note that these are only fired if the **ROWEVENTMODE** is True). It is also worth noting that, as with previous versions of OpenInsight, using the **DELETE** and **INSERT** methods to programatically modify the EditTable contents will //not// trigger the **INSERTROW** or **DELETEROW** events (or any subsequent **INSERTEDROW** and **DELETEDROW** events either).


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