Unable to Use Output from dorny/paths-filter@v2 in Startegy Matrix ( Github Action )

I am trying to take output from dorny/paths-filter@v2 which is actually a list of files that got changed, and use it as a multiple input for Strategy matrix in Github Actions.

Although i see relevant file path that got changed, which looks something like "aws/dev/something/yo.yaml" for eg. in the plugins output, but the strategy matrix just dont like it and throws errors like

Error when evaluating 'strategy' for job 'deploy'. .github/workflows/main.yaml (Line: 59, Col: 15): Error parsing fromJson,.github/workflows/main.yaml (Line: 59, Col: 15): Unexpected character encountered while parsing value: a. Path '', line 0, position 0.,.github/workflows/main.yaml (Line: 59, Col: 15): Unexpected value ''

My Github Action file

name: Yo

on:
  push:
    branch:
    - main


jobs:
  changes:
    runs-on: ubuntu-latest
    outputs:
      files: ${{ steps.filter.outputs.aws_files }}

    steps:
    - uses: actions/checkout@v2

    - uses: dorny/paths-filter@v2
      id: filter
      with:
        base: ${{ github.ref }}
        list-files: 'escape'
        filters: |
          aws:
          - added|modified: 'aws/**'

  deploy:
    runs-on: ubuntu-latest
    needs: changes
    strategy:
      matrix:
        file: ${{fromJson(needs.changes.outputs.files)}}
      fail-fast: false

    steps:

    - name: Lets See
      env:
        file: ${{matrix.file}}
      run: |
        echo ${{env.file}}

Tried multiple option of the plugin like shell, csv but no luck

Solution

The issue is that strategy matrix expects the response from fromJSON to be an array. That's not happening here, and hence the error.

So you need to make sure dorny/paths-filter@v2 send back the list of files formatted as a JSON array.

- uses: dorny/paths-filter@v2
  id: filter
  with:
    base: ${{ github.ref }}
    list-files: 'json'
    filters: |
      aws:
        - added|modified: 'aws/**'

Notice that list-files: 'json' instead of list-files: 'escape'.