Parsing Rails Model Errors in CoffeeScript

Question

I'm trying to parse out validation error messages returned from a Ruby model on the client side, but I am running into problems.

The application returns errors in JSON as expected:

"{"error":{"first_name":["can't be blank"],"last_name":["can't be blank"]}}"

I cannot figure out how to parse the errors out of the JSON. I would like to parse out each component pair...i.e. get the field (first_name) and error message ("can't be blank"), but I keep running into errors.

How can i parse these individual pieces out of the response? I suppose i lack understanding of how to parse the json string into each of its respective components.

I've included the relevant ajax:error function below. I appreciate any help! Thank you!

$ ->

  $(document).on "ajax:error", "form", (evt, data, status, xhr) ->
    list_area = $('#error-explanation ul')
    list_area.empty()
    for own key, value of errorList
      console.log "#{key} -> #{value}"

The code above outputs to the console:

error -> [object Object]

I was expecting to see first_name -> can't be blank. I believe I am not parsing the object correctly.

JSON.stringify converts a JavaScript value to a JSON string. I don't think you want to be doing that. Your data should be (I think) a js object that you can work with directly. BTW, it might be easier/nicer to send back rendered errors html and append that. — jvillian
– jvillian, Commented Jul 27, 2018 at 22:17
I actually just output the string to see if the correct JSON data was being returned. As far as the return structure, I have the capability of assigning messages to specific fields (versus one list of all errors). But I cannot figure out how to parse the json object. — flewis
– flewis, Commented Jul 28, 2018 at 1:14
I updated the question with my attempt at parsing the json into the respective errors. I believe I'm one level off on the json object. — flewis
– flewis, Commented Jul 28, 2018 at 13:25

flewis · Accepted Answer · 2018-07-28 13:55:41Z

1

OK, I solved this problem. I just didn't understand how to get to the nested object in json.

I just needed to point to the correct data in the parsed json object:

$(document).on "ajax:error", "form", (event, data, status, xhr) ->

errorList = JSON.parse data.responseText
for own key, value of errorList.error
  console.log "#{key} -> #{value}"

Thanks for the response jvillian!

answered Jul 28, 2018 at 13:55

flewis

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