topic Re: Interacting with Relationship Class Beyond Creation Possible? in Python Questions

Interacting with Relationship Class Beyond Creation Possible?

Glasnoct — Tue, 01 Apr 2025 13:27:21 GMT

I'm currently trying to wrap my head around relationship classes and there seems to be a dearth of information on interacting with them beyond the ability to create them or describe them. Is reading from/writing to RCs not exposed in the arcpy API? Even in the GUI the RC object doesn't give me any ways to introspect it; I can't open it as a table to see *what* is in it, if anything.

Can I add relationships to it by providing the key pair? Is it an SQLite database like .stylx files are and I'd have to interact with it via the SQL python module? I can find a dozen example on *creating* a relationship class with arcpy but nothing beyond that--even finding the RC in the database in convoluted and only returns the describe object as opposed to the actual RC object itself.

If I can't interact with it meaningfully with arcpy, is it exposed in another API I can stumble my way through to modify it?

Re: Interacting with Relationship Class Beyond Creation Possible?

AustinAverill — Tue, 01 Apr 2025 14:17:59 GMT

I am not entirely sure I am following.... But the following technical article outlines how to add additional fields to a relationship - https://pro.arcgis.com/en/pro-app/latest/help/data/relationships/modify-a-relationship-class.htm.

That link also provides some other guides and a table of available functions. Does this not cover what you need? Or?

Re: Interacting with Relationship Class Beyond Creation Possible?

Glasnoct — Tue, 01 Apr 2025 18:54:57 GMT

Unless I'm not seeing it, this all pertains to the properties of the relationship class and not the data it holds. I essentially need the Search/Update/Insert cursor equivalent for the table/file/whatever that holds the actual key entries that dictate "this feature is related to that feature"

Re: Interacting with Relationship Class Beyond Creation Possible?

AustinAverill — Tue, 01 Apr 2025 19:22:31 GMT

Are you working with an attributed relationship class? If so, the article details how to add fields and has a link to the info on populating the relationship class table.

If you aren't working with an attributed relationship class, then I don't believe there is any modifications you can do...

Re: Interacting with Relationship Class Beyond Creation Possible?

Glasnoct — Wed, 02 Apr 2025 01:09:09 GMT

I was initially not, no. Which would explain the inability to see any of the relationships. Why attribution is disabled by default when creating a relationship class, I do not know but at the same time I haven't really wrapped my head around all there is to be aware of with relationship classes.

Once I got the RC regenerated as attributed, I was able to get access to the intermediate table. Using a regular InsertCursor seems to have updated the table as a test without complaint, so hopefully that should satisfy my original question.

I am a little perplexed, though. If it were as simple as running the typical cursors on the intermediate table, why was I not finding any discussion about that? I had run into a road-block with programmatically affecting relationship classes at a previous job where there seemed to be no answer outside of possibly doing it through the C# SDK for ArcPro (if I recollect). Maybe the lack of attribution was the cause, as I don't remember being able to access the relationships as easily as opening up an intermediate table of the relationship class. 🤔 Our M.O. at the time was to manually select and create the relationship through the context menu, over and over again, across thousands of features--easily the worst part of our workflow. I did just try this now with a 1:M relationship type; maybe the M:N relationship class was what we were using and may prove to be an issue. Something I'll have to test later...

Re: Interacting with Relationship Class Beyond Creation Possible?

AustinAverill — Sun, 06 Apr 2025 14:32:22 GMT

Defintiely report back your findings! Even as popular as Python has become there are still a lot of things that aren't documented well in discussions when it comes to the various ESRI python libraries. I find myself often digging through the documentation for things when using the API for Python library because people seem to have not had very extensive discussion about a lot of the extended functionalities!