Attribute Rule to Populate a Field When a Line is Split

ZachBodenner

Hello,

Scenario: A line feature class (Trails) is used in an asset management where unique IDs of specific segments tie the segment to past work orders. Sometime these trail segments need to be split into two separate lines. Down the road, I foresee the possibility of work orders getting 'lost' by retaining their relationship to only part of a line segment. Here's what I want to do:

Add a field to the dataset to hold a 'Parent ID' so that a child line segment created by splitting will retain at least a textual reference to a previous line. However, because I do not want two lines with the same ID, I want one line to maintain that original ID, and have the second line 1) inherit the ID to the 'Parent ID' field, and then get a new ID in the primary ID field.

I had the idea to use an calculation rule to run on insert, as splitting the line segment should trigger an Insert edit. Then, as a result of that edit I would A) Generate a new ID in the primary ID field of the new line and run an Intersect function and get the original ID from the parent line to populate into the Parent ID field. My concern (and I haven't tested this yet to be honest), is that this might get complicated by the fact that many times the resulting new trail line will intersect multiple other line segments. Any thoughts on how I could single out one specific line segment? There's no guarantee the 'Parent' trail segment is actually First() in the OBJECTIDs, so I'm reluctant to rely on First to do this.

ZachBodenner

Hey @JoeBryant1 , thanks for the idea! Ultimately, I think I found a slightly simpler solution using a pair of instant calculation rules. I also don't necessarily need a shorter line to be the 'child' so I'm just operating as new feature from split = 'child' feature. Here's the set of three total rules.

// RULE 1 - Initial Trail ID
// If there is no trail ID, assign a new one. If the TrailID exists, keep it the same. 
var trlID = IIF(isEmpty($feature.TrailID),"TRL-"+$feature.objectID,$feature.TrailID)
return trlID

// RULE 2 - Populate Parent Trail ID if the result of the edit results in two or more segments with the same TrailID
var id = $feature.TrailID
var oid = $feature.OBJECTID

// Check if this TrailID already exists in the dataset by filtering based on TrailID AND make sure the object ID of the INSERTED feature is different from any found matches.
var existingTrails = Filter(FeatureSetByName($datastore, 'Trails_Test'),"TrailID = @id AND OBJECTID <> @oid")

// If this ID already exists, this is a split - save the ID as ParentTrailID
if (Count(existingTrails) > 0) {
    return id
}
else {return null}

 

// RULE 3 - The previous rule calculates the TrailID into ParentTrailID but does not affect the TrailID. Now, go back and create a new TrailID for the new feature.
var id = $feature.TrailID
var oid = $feature.OBJECTID

// Check if this TrailID already exists in the dataset by filtering based on TrailID AND make sure that the object ID of the INSERTED feature is different from any found matches.
var existingTrails = Filter(FeatureSetByName($datastore, 'Trails_Test'),"TrailID = @id AND OBJECTID <> @oid")

// Count the number of matches. Count higher than 1 indicates more than one line with the same ID. If this ID already exists, this is a split - generate new ID for the INSERTED feature...
if (Count(existingTrails) > 0) {
    return "TRL-" + Text(oid)
}
// ... otherwise, keep the ID the same
else {return id}

 

So ultimately I think I was thinking too hard about my initial problem. This solution should also make this a bit more efficient by not having to rely on geometry at all.