Filtering nested JSON in JavaScript transformer

App Building
1

If an API request for users returns data in the following JSON format:

[
  {
    "ID": "1234",
    "Name": "Jane Doe",
    "Permissions": [
      {
        "Item": "abcd",
        "Allow": true
      },
      {
        "Item": "efgh",
        "Allow": false
      }
    ],
    "Profile": "wxyz"
  },
{
    "ID": "5678",
    "Name": "John Smith",
    "Permissions": [
      {
        "Item": "ijkl",
        "Allow": true
      }
    ],
    "Profile": "wxyz"
  }
]

while a different API request for Permissions returns data in the following JSON format:

[
  {
    "ID": "abcd",
    "Name": "Level 1",
  },
  {
    "ID": "efgh",
    "Name": "Level 2",
  },
  {
    "ID": "ijkl",
    "Name": "Level 3",
  }
]

How would I be able to use the JavaScript transformer to return a object with a user's ID, Name, and Permission names?
(eg. 1234 | Jane Doe | Level 1, Level 2)

I don't seem to be able to read properties of the nested JSON using indexing, such that I cannot find the object where the Permission.ID equals the User.Permissions.Index.Item.

I've tried the following to even get the first item of a user's permissions, but am told message:"Cannot read properties of undefined (reading 'Item')"

const users = {{getUsers.data}}
const permissions = {{getPermissions.data}}

let final_data = [];
Object.keys(users).forEach(key=> {  
  let new_obj = {}
  new_obj['id'] = users[key]['ID']
  new_obj['name'] = users[key]['Name'] 
  new_obj['permission'] = permissions.find(obj => obj.ID === users[key]['Permissions']['0']['Item'])
  final_data.push(new_obj)
})
return final_data;

Your help would be much appreciated!
Thomas

2

If the data that is being returned from your resource contains a column of JSON data -- its possible that data is still just a string. You may have to convert that string to an object:

const permissions = JSON.parse(getPermissions.data)
3

Thanks for the response, but I don't think that's it. {{ getUsers.data }} as far as I can tell is already an Object, so trying to JSON.parse it would just throw an [object Object] is not valid JSON error.

The issue seems to be in accessing keys within a user's Permissions property. It's probably the way I was trying to filter out if the property was null before attempting to get each of the names (not shown in above code).

4

Ahh ok, so its more about the code you are trying to write. I think you can do something like this:

users.map( user => {
   // current users permissions mapped
   const mappedPermissions = user.permissions.reduce( (result, permission) => {
      const namedPerms = perms.filter( perm => perm.ID === permission.Item && perm.Allow )
      if( namedPerms.length ) {
       result.push({ 
         ...permission,
         name: namedPerms[0].Name
       })
       return result
   }, [])
   return {
      ...user,
      permissions: mappedPermissions 
    }
}}
  1. We map (loop) over the user
  2. Then we reduce (loop with a map) over that users permissions
  3. For each of those permissions we find the corresponding Perm (using filter)
  4. If we got a perm and that perm was allowed we copy the name into the current users permissions

This is obviously not tested -- but this should give you a head start

2 Likes
5

Thanks. That got me sufficiently started.

Strangely, what I was doing before worked in JavaScript a different tool I was using.

1 Like
6

@ThomasLu_EarthDaily glad that helped!

7