How to prevent a field from being editable

Hi, I'm practicing modifying the Position object in the Fundamentalls book. I have both Close Date and Days Open defined to be read-only (non-editable) fields. It works properly for Days open (which is a number), but not for Close Date (which is a Date type).

When I change Close Date, it turns red, then accepts the change. Why is it allowing me to edit this, because both the field-level security, and the field property on the form are specified as "Read Only"

3 Answer(s)


Researching the Internet I found if you don't want any users to be able to change a value, you should use Field Level Security (FLS) to make it read-only on a profile-by-profile basis:

1. Go to the object's field page under Setup
2. Click on the view link for the field
3. Click the Set Field-Level Security button
4. Change the field to read-only for the appropriate profiles (You would need to change to appropriate profile to test)

Note: Only use a validation rule for this when the field should be read-only only under certain circumstances; for blanket coverage modifying FLS is more appropriate.
Note: To set it up so the user can insert an initial value but not update an existing one you can use the following validation rule:


This will allow the user to enter a new value assuming no prior value has been entered, but once a value is set, it is locked in place.


In my example, I do have FLS set to read-only, for all profiles. I also have the field set to read-only on the page layout. When I create a new instance of my custom object, I'm still able to click on the calendar and enter a date.

I was wondering if there's something different about dates, where you can't prevent this from happening.


Hi Keith, Sorry for the late reply, I am little busy these days in my sister's wedding. So to answer your question, you have system admin profile and remember when we discussed profiles I told you guys that System Admin profile can see all data because it has View All and Modify All permission by default and also have a permission to view read only data. So if you want to see your changes then please login from any other profile.

Let me know if you still have any doubt.