you'll probably get more responses if you post in the general discussions section instead of the UK community events section, which is probably only going to be seen a very small number of people...
Thank you very much
Good point Ian…
In the meantime, Muhammad, you should be looking in the Manage Security section. You will need to understand the basics of Accounts and Privilege sets for this. You will need to create a new Privilege Set (or sets) which can be assigned to the login accounts you wish to restrict. You need to set the Records to have Custom Privileges. In that dialog, select the table that you want to lock down and set the Edit and Delete options to limited. This opens a calculation dialog where you can enter your formula. Your formula would be something like:
IsEmpty ( signatureField )
This will allow the user to edit and delete only when the signature field is empty and they are assigned that Privilege set.
Make sure that you have an account with Full Access for development even if you will normally use another account.
Concur that manage security and the right settings on the permissions sets are the way to solve this.
Its a data layer issue and best solved with data layer controls
You should also be aware that any "Full Access" accounts will be able to edit the record one way or another. I'm not aware of any mechanism within FileMaker that will permanently lock a field or record from *any* future modification. You can lock it down on a layout, but a full access user could create a new layout based on the same TO and have the fields be editable. If you lock the fields down in the Manage Database dialog, a full access user can alter the validation on any field to effectively remove your locks.
Actually you can prevent this using FileMaker Pro Advanced by removing admin access (the [Full Access] privilege set) completely from the file in the Developer Utilities area, but beware - this means you will never be able to make any changes to the logic or structure (tables, fields, scripts, layouts etc) in that database again because the removal is permanent.
You would choose to do this only if you have completed development and want to release the solution. If you do so, you should always keep an empty backup copy without admin access removed, which you can clone and continue developing.