topic Re: Joins leave Join fields empty in ArcGIS Pro Questions

Joins leave Join fields empty

noahhunter13 — Sat, 26 Mar 2022 20:04:35 GMT

I've been having issues with joins for a few weeks now in my GIS class. Whenever I try to do a join with any tool except the "Join Field" tool, all of the fields from my join table come back <Null>. I was able to successfully join two tables for last week's assignment with the "Join Field" tool, but this week we're using spatial joins so that's not an option. I have a polygon layer and a point layer, and I want to perform a one-to-one join using the "Intersect" operation. This is my dialog box:

This is the product of the operation (every field after EJ_SYM is from the MA_chems_NAD point layer):

Again, this has happened for both spatial joins and join by attribute. I've examined the data types for each field, and I don't see anything that would be incompatible. The field names also only contain letters and underscores. Others in my class have been able to do this successfully using the same data.

Thanks in advance for the help!

Re: Joins leave Join fields empty

DanPatterson — Sat, 26 Mar 2022 21:25:14 GMT

Are you joining the points to a polygon layer or a polyline? (if the latter, you shouldn't use intersect)

Are both in the same coordinate system?

Re: Joins leave Join fields empty

noahhunter13 — Sat, 26 Mar 2022 21:30:41 GMT

I believe its a polygon, I haven't used polyline before (I think). The point layer was originally a table that I used the "display xy data" tool on, then projected into the same system as the polygon (using the project tool).

Re: Joins leave Join fields empty

DanPatterson — Sat, 26 Mar 2022 21:56:09 GMT

right click on the layers and check their Properties to make sure. If you open the tables, a polygon layer will have a Shape_area field and a polyline won't.

Intersect isn't going to work properly if it is a polyline. And even if it is a polygon, try something else, even skipping the one-to-one to make sure that there are some joins. If there aren't, then they don't reside in the same "space"

Both should reside in the same file geodatabase as featureclasses and have the same coordinate system to be sure.

Re: Joins leave Join fields empty

noahhunter13 — Sat, 26 Mar 2022 22:37:40 GMT

Checked out the properties Source tab, and the Geometry was Polygon. I also tried a one-to-many join with the Contain process instead of intersect and still nothing. This was also happening for a previous project when I was doing a simple join-by-attribute using FIPS code identifiers. Although in that case, the join appeared to work but would break when I tried to export features to make it permanent.

Re: Joins leave Join fields empty

DanPatterson — Sat, 26 Mar 2022 22:58:53 GMT

points are "Within" a polygon during a spatial join

and a bunch of those polygons will have no points (hence the nulls) so make sure you check the resultant table

Re: Joins leave Join fields empty

noahhunter13 — Sat, 26 Mar 2022 23:00:05 GMT

The join actually did work. I didn't realize that because most of my polygons didn't have a point within them, most of the rows in my joined file had null values and so I had to scroll past a lot of empty rows before I found the matched entries.