How to create ArcPy script that checks for duplicates and warns if adding one?

Question

I am new to GIS(Arcpy)/Python programming , but I have experience in other languages. I have a question regarding the possibility to create a tool/script that does the following

-- Check a specific attribute field and see if there are any Duplicates (Our problem is that our DOC_ID field is supposed to be a unique value but some interns are accidently pasting/writing the same DOC_ID from a previous edit and saving it.

*The checking for duplicates is not that important as I have create a seconday field to check the data within the DOC_ID field to find duplicates*

-- Is it possible for the tool / script to be continuous. What i mean for this is that if a user accidently inputs a DOC_ID that is already within the list ... some kind of error or warning message would pop up saying that the "DOC_ID has already been used".

  ^(This is the main feature that I am trying to create or solve.) 

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If this is not possible, are there any other paths that I should consider. (Validation Rules , etcetc)

This is not a big problem currently. There are only around 100-200 duplicate entries so far. We are trying to avoid the problem the best we can early once we start to implement more and more entries.

Answer 1

You might be interested in the ArcGIS for Local Government Attribute Assistant add-in. It's a customizable editor extension that you could use to manage your unique ID field. It would need to be set up on each editor's machine.

The Attribute Assistant uses a series of predefined methods to automatically populate attributes when updating or adding new features to the geodatabase. For example, one method populates the full road name on each road centerline and site address feature from a valid list of road names contained in a master street name table. Other methods help you maintain the integrity of your address data by populating a unique identifier, last editor, and last update date on each feature.

Component                        Description
------------------------------------------------------------------------------------------
Attribute Assistant toolbar      Contains the tools to update the attributes of selected
                                 features based on the rules defined in the Generate ID
                                 table and Dynamic Value table

Generate ID table                Used to generate unique identifiers for features

Dynamic Value table              Contains rules defining how attributes are updated