map-action

GitHub Action that picks a value from a JSON or YAML map by key and exposes it as a step output. Useful for environment-to-value lookup tables (per-env URLs, image tags, feature flags) that you would otherwise duplicate across workflow if: blocks.

Usage

Scalar value per environment

- uses: nerjs/map-action@v0.1.0
  id: api
  with:
    key: ${{ github.ref_name }}
    default_key: main
    map: |
      main: https://api.example.com
      staging: https://api.staging.example.com

- run: echo "${{ steps.api.outputs.value }}"

outputs.value holds the scalar matching key, falling back to default_key when key is empty or not found.

Object value: every field becomes an output

- uses: nerjs/map-action@v0.1.0
  id: env
  with:
    key: ${{ github.ref_name }}
    default_key: main
    map: |
      {
        "main":    { "url": "https://api.example.com",         "tag": "stable" },
        "staging": { "url": "https://api.staging.example.com", "tag": "edge" }
      }

- run: |
    echo "${{ steps.env.outputs.url }}"
    echo "${{ steps.env.outputs.tag }}"

When the looked-up value is an object, each top-level field becomes its own output. output_key_name is not allowed in this case.

Custom output name for scalar values

- uses: nerjs/map-action@v0.1.0
  id: tag
  with:
    key: ${{ github.ref_name }}
    default_key: main
    output_key_name: image_tag
    map: '{"main":"stable","staging":"edge"}'

- run: docker pull myimage:${{ steps.tag.outputs.image_tag }}

Inputs

Name	Required	Description
map	yes	Mapping as a JSON object or YAML mapping at the top level.
key	no	Primary key to look up. Either key or default_key must be set.
default_key	no	Fallback key used when key is empty or not present in the map.
output_key_name	no	Output name when the value is a scalar. Defaults to value. Not allowed for object values.

Outputs

• When the value is a scalar - a single output named output_key_name (value by default).
• When the value is an object - one output per top-level field of that object.

Notes

• Top-level arrays and scalars are rejected: map must be a key-value structure.
• Output values are not auto-masked. If your map contains secrets, call core.setSecret on them in a prior step.
• Forbidden output names: __proto__, prototype, constructor.

License

MIT.