Restricting End User Calc column functions

rbuser

Using: rb6.03, D6, Custom Report Explorer with dictionary with daAsta.

In Dade I need to restrict certain users from creating/updating a
calculated column of type expression.

That is, specifically I would like them to be able to see existing
ones but not to be able to create or edit them.

What is the recommended method?

Separately I would like to slightly change (in some cases) the sql
string that is produced for a field (TdaField.SQLString I believe).
Is there a way of overriding the method?

Many thanks,
Rick Matthews
Dartek Systems Inc.

digitalmetaphors

It shouldn't be too dificult to access the TdaSQL object before the report
prints to clear the calc fields that the user has added. After the tempalte
has loaded, extract the SQL object and save a list of the calc fields. Then
check these in the BeforePRint of the report to make sure these are the only
calc fields listed. The only problem is that you'll also have to do this
when they preview the data on the dataview. There is no notification sent
to the outside world when this happens. You'll have to modify the source to
send a Delphi event or send an event notification with a TppCommunicator
object.

Here is an example of accessing the TdaSQL object in code. Have a look at
TdaSQL in daSQL.pas for the interface to this class. In this class are all
the calc field methods and properties you need to alter the calc fields
defined on this object.

http://www.digital-metaphors.com/tips/ExtractSQLObject.zip


Cheers,

Jim Bennett
Digital Metaphors

rbuser

Thanks Jim for the guidance.

However, if I understand you correctly this will mean that the user
will be able to create and edit these calc fields as well as use them
on their report. However at print time they would be removed.

This, I think, will create support problems and confused users.
Really I need to stop them from editing the expression field so that
they know they are not allowed to do it.

Also, do you have any thoughts on the TdaField.SQLString part of the
post?

Many thanks for your very speedy replies.

digitalmetaphors

Yes, this is possible (I just created a demo that does it). It involves
creating a custom dataview descendent. This is not a template, but rather a
replacement of the TdaBDEQueryDataview class. You can unregister the
TdaBDEQueryDataview class and register this new class you can download:

http://www.digital-metaphors.com/tips/NoCalcDV.zip


Cheers,

Jim Bennett
Digital Metaphors

rbuser

Thanks very much for the excellent service.

I will follow you example and try to get specifically what I need.

Thanks again.

digitalmetaphors

I forgot to mention, this is just an example of replacing the BDE query
dataview class. You can follow the same approach for any other plugin that
you are using, such as DBISAM, Advantage, IBO. Look in your DADE plugin
unit, and find the query dataview class that is being used. For example, if
you are using DBISAM, then you would replace the TdaDBISAMQueryDataView
class with your own descendent.


Cheers,

Jim Bennett
Digital Metaphors

rbuser

Thanks Jim I had noticed that and replaced the Asta
TdaAstaQueryDataView.

That works for me, however it doesn't solve my problem. It stops
access to the Calc button but if you click any other button you get
the Query Designer Form with all of its tabs.

What I really want is to allow all users access to the calc tab but
restrict the calc type of "expression" to specific users (view only
for some).

I don't see any way of doing this short of either making a complete
local copy of daQueryDesigner since the instance of
TdaQueryDesignerForm is a private of TdaQueryDesigner. Am I missing
something here?

Thanks,

digitalmetaphors

Replace the query designer. The replacement can disable the calc tab. Here
is an example of replacing the query designer.

http://www.digital-metaphors.com/tips/ReplaceQueryTools.zip


Cheers,

Jim Bennett
Digital Metaphors