Extracting a nested attribute from geojson in velocity using Arcade

Question

I have a geojson live feed in Velocity. The data comes in fine, however my main core of attrbutes are all nested together in one attribute column. I know in Velocity, I can add fields, but I do not know the arcade functions needed to break down the nested attributes into their own new fields. Can someone help me with the arcade?

currentConditions[{"id":3023658,"conditionId":17,"conditionDescription":"3 - dry","userName":"","startTime":1729576800213,"endTime":4883216432298,"confirmationTime":1729616432298,"updateTime":1729576800213,"confirmationUserName":"","sourceType":"OPERATOR","additionalData":null},{"id":3026261,"conditionId":47,"conditionDescription":"forecast text included","userName":"","startTime":1729616555832,"endTime":1729638039767,"confirmationTime":1729616439767,"updateTime":1729616439767,"confirmationUserName":"","sourceType":"NDFD","additionalData":"Clear skies. Wind gusts of up to 21 mph are expected."}]

NateRogers1 · Answer

so I was struggling with this and I had an idea that seems to work. Instead of struggling with the arcade, I can connect to the feed twice, once as a geojson to get the geometry but exclude out all attributes except the id field, then I can create a new feed as a JSON so I can flatten the attributes but with no geometry then in Velocity I can use the join field to join the geojson ID field with the JSON id field so I get both geojson geometries with the fixed attributes.

Joanna_Nishimura · Answer

Hi Nate- I totally understand, Arcade can be a little bit of a learning curve.

I would start with the function reference documentation here.  If you're looking to learn more about parsing data returned in an array, maybe first focus on the Array functions area first.

Another quick resource that I like to use is the ArcGIS Arcade Playground.  In the screenshot below, you can see how I took the Arcade snippet that I provided, and replaced the currentConditions variable with the text that you initially provided.  Then I'm able to execute the Run the expression and change my expression to change the output results.

Some other Velocity-specific resources for Arcade:

Using Arcade in ArcGIS Velocity

Best practices for Arcade expressions in ArcGIS Velocity

-Joanna

NateRogers1 · Answer

Hi Joanna,

Thank you so much for taking the time to help. I want to keep the feed as a geojson because there are a mix of points and polylines and if I turn the feed into a json, those extra coordinates needed for the lines disappear as it only becomes a begin xy to end xy and doesnt pick up all the middle verticies.

I am completely terrible at Arcade, do you know of any resources or would be able to help parse out more what the arcade function would look like? Thanks!!!