Arcade expression that selects the nth element in a dynamic table attribute based on map series rows

Question

I have a map series layout that displays all the photo attachments associated with each feature in a line feature class, housed in a file geodatabase. This line feature class is the index layer of the map series based on Route IDs. A line feature can have as little as 1 photo attachment or as much as 8 or 9. I also have a point feature class that represents each photo taken along each linear feature. So for example, Route N974 will have 3 point features with a field titled [pt_number] that represents photo 1 along the route, photo 2 along the route, and photo 3 along that route.

Currently, I have all the potential photo attachments in the layout manually labeled as 'Photo 1', 'Photo 2', etc., but I then have to manually add/remove photo labels in the layout for each map series page due to the variable number of photos attached to each feature. So to fix this, I am trying to write an Arcade expression that will dynamically label the photos so, for example, if there isn't a 4th photo attachment, that label just doesn't show up in the export and I can iterate through all features in one go without needing to make changes between map series pages. Currently, if there isn't a 4th attachment to fill that slot in the layout, no photo or anything appears in the export, which is also what I want the photo labels to do.

I am using a table attribute dynamic text element to do this, with the source table being that photo point feature class. But I cannot figure out the proper Arcade syntax to essentially select the nth element of the variable... And I probably am not stating/asking this correctly/accurately which is why I am having trouble finding a solution. Right now, I have this:

Where it is labeling all three photo points (result on the left), but I want to be able to tell it to just select the first element and just get 'Photo 1' for the first label, and so on. I feel like I should be able to write something like this (similar to how R works):

'Photo ' + $feature.pt_number[1]

Don't know if I am barking up the wrong tree here/if this is possible. Any other suggestions on how to solve this problem? Using ArcGIS Pro, version 3.1.0

Answer 1

If you are following the steps in Spatial map series and dynamic elements, then this lets a user add a picture and later access that. On the same page it explains how to use figure using the url (location of your file on the disk):

"https://" + $feature.DomainName + TextFormatting.BackwardSlash + $feature.URLFileName + ".jpg"

There should be a field on your data table where the url is stored, basically. Maybe you are already trying that, but it is hard to follow your question as it is not very well posed.

If you want to grab only the first photo you can use First():

First($feature.URLFileName) + ".jpg"

If you want to loop through them you need a function:

var photoname = 'test'
    for (var x in $feature.FID){
      photoname = photoname + TEXT(x) + '.jpg'
    }
return photoname