Using Migrate API to select items from a JSON array

Question

I have a module pulling a JSON feed into Drupal 8 using the Migrate API. However, one of the values in the JSON is an array.

For example, coordinates:

{
    "data": [
        {
            "id": "id:1",
            "position": {
                "coordinates": [
                    24.932974,
                    60.168495
                ],
                "type": "Point"
            },
            ...
        },
        {
            "id": "id:2",
            "position": {
                "coordinates": [
                    24.94416,
                    60.18831
                ],
                "type": "Point"
            },
            ...
        },
...

What sort of field selector is needed to get coordinates?

If I use selector: position/coordinates I get 24.932974.

• How would I get the second one: 60.168495?

• Should the extract plugin be used here?

Answer 1

First, use a selector like this:

-
  name: position
  label: 'Position'
  selector: position

Then use this for the first value:

field_description:
  plugin: extract
  source: position
  index:
    - coordinates
    - 0

And this for the second value:

field_description:
  plugin: extract
  source: position
  index:
    - coordinates
    - 1