I am currently spatial joining two feature classes like this


I need to access the object ID of each join feature that was joined to the target feature. However, in spatial joins, arcpy only adds "JOIN_FID" in one-to-many joins. In a one-to-one join I only get "TARGET_FID" (which seems pretty useless as I knew that already).

How can I access (programatically) the feature ID of the joined feature from the output feature class?

  • 1
    Why can't you use a one-to-many join, to access the JOIN_FID? – Aaron Jun 25 '14 at 16:40
  • Doesn't one-to-many only join features which intersect? – Sideshow Bob Jun 26 '14 at 9:31

Very interesting! I think the simplest way of doing this is to create a brand new field in your joining featureclass, copy the object ID's into it and do the one to one spatial join.

As you are doing a closest join a more complex approach would be run a one to many spatial join but make sure you set the optional distance field name to something. Then the output table can be run through a summary statistics tool filtering for the minimum distance and the case field being the FID. This way get your JOIN_FID field but this not an efficient approach if you have thousands of features to join to and from.

  • This is what I did in the end (copying the object IDs). Seems odd that Arc doesn't provide the JOIN_FID, but stranger things have happened before. – Sideshow Bob Jun 26 '14 at 9:32

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