How to maintain Shape_Length field afer Spatial Join of Point to Polyline feature classes?

Question

I need to get for each point the length of the line that joining to the point.

How to maintain the "Shape_Length" field of polylines when I'm Spatially Joining point to lines feature classes ? When I'm using the normal "Spatial join" tool this field isn't appear at the point output layer. Apparently because this is the default field of line feature class it disappeared at point layer.

Answer 1

You are hitting a system limit in what you are trying to do.

ArcGIS system fields, such as Shape_Length, Shape_Area, OBJECTID, have their attribute values maintained by ArcGIS and thus cannot be treated like ordinary fields in the way that you wish.

For example, if you were to spatially join a point to a line, and then the line is extended so that it is has a longer Shape_Length in the line feature class, then what should happen to the "Shape_Length" field whose values you transferred to the point becomes problematic. I see two options:

1. Its values could be frozen - but you can already do this by adding a field and calculating it equal to Shape_Length prior to the spatial join (like @Barbarossa has suggested)
2. It could have a dynamic link maintained but this would involve relating the line and point feature classes in something like a topology, geometric network or network dataset, and thus having them stored in a feature dataset.

For either of the above you would be looking at trying to convince Esri of the need to add this additional functionality to ArcGIS via ArcGIS Ideas . Option 1 above would be the easier to implement but it is so easy to workaround so there is little incentive for that to happen. Option 2 would have far reaching consequences so I think would stand little chance of being implemented, unless a compelling business case emerges to do so (which I do not see happening in the foreseeable future).