JSON Validator TypeScript Action

A GitHub Action to validate JSON files in your repository, with optional JSON Schema validation support.

Features

• ✅ Validates JSON syntax in your repository
• ✅ Optional JSON Schema validation
• ✅ Automatic schema detection from $schema property
• ✅ Supports relative and absolute schema paths
• ✅ Configurable ignore patterns - customize which files/folders to skip
• ✅ Optional failure mode - choose whether invalid JSON fails the action (default: true)
• ✅ Configurable folder scanning (defaults to entire repository)
• ✅ Clear error reporting with file paths
• ✅ Defaults to ignoring node_modules, dist, lib, and .git folders
• ✅ Comprehensive test suite

Usage

Basic Usage - Validate All JSON Files

name: Validate JSON Files
on: [push, pull_request]

jobs:
  validate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: woeterman94/json-validator-typescript-action@v1

Validate JSON Files in a Specific Folder

- uses: woeterman94/json-validator-typescript-action@v1
  with:
    folder: 'config'

Validate JSON Files Against a Schema

- uses: woeterman94/json-validator-typescript-action@v1
  with:
    folder: 'data'
    schema: 'schemas/data.schema.json'

Custom Ignore Patterns

You can customize which files and folders to ignore:

- uses: woeterman94/json-validator-typescript-action@v1
  with:
    folder: '.'
    ignore: |
      **/node_modules/**
      **/dist/**
      **/build/**
      **/.git/**
      **/temp/**

Or use comma-separated patterns:

- uses: woeterman94/json-validator-typescript-action@v1
  with:
    folder: '.'
    ignore: '**/node_modules/**, **/dist/**, **/build/**, **/.git/**, **/temp/**'

Automatic Schema Detection

JSON files can specify their own schema using the $schema property. The action will automatically validate these files against their specified schema:

{
  "$schema": "./user.schema.json",
  "name": "John Doe",
  "email": "john@example.com"
}

This feature works with:

• ✅ Relative paths (e.g., ./schema.json, ../schemas/user.schema.json)
• ✅ Schemas stored in the same repository
• ❌ HTTP/HTTPS URLs (only local schemas are supported)

Note: If a global schema input is provided, it takes precedence over individual $schema properties.

Output Format

When invalid JSON files are found, the action always displays them in this format:

Found invalid or incomplete json files:
❌ ./path/to/file1.json
❌ ./path/to/file2.json

This output format is consistent regardless of the fail-on-invalid setting. The fail-on-invalid parameter only controls whether the action exits with a failure status code.

Inputs

Input	Description	Required	Default
folder	Folder location to scan for JSON files	No	. (repository root)
schema	Path to JSON schema file for validation	No	`` (syntax validation only)
ignore	Glob patterns to ignore (comma or newline separated)	No	**/node_modules/**, **/dist/**, **/lib/**, **/.git/**
fail-on-invalid	Whether to fail the action when invalid JSON files are found	No	true

Outputs

Output	Description
valid-files	Number of valid JSON files found
invalid-files	Number of invalid JSON files found

Examples

Complete Workflow Example

name: Validate Configuration Files
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  validate-json:
    runs-on: ubuntu-latest
    name: Validate JSON Files
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
      
      - name: Validate all JSON files
        id: json-validation
        uses: woeterman94/json-validator-typescript-action@v1
        with:
          folder: '.'
      
      - name: Output results
        if: always()
        run: |
          echo "Valid files: ${{ steps.json-validation.outputs.valid-files }}"
          echo "Invalid files: ${{ steps.json-validation.outputs.invalid-files }}"

Validate Multiple Folders

jobs:
  validate:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        folder: ['config', 'data', 'schemas']
    steps:
      - uses: actions/checkout@v4
      - name: Validate ${{ matrix.folder }}
        uses: woeterman94/json-validator-typescript-action@v1
        with:
          folder: ${{ matrix.folder }}

Report Invalid Files Without Failing

You can set fail-on-invalid: false to report invalid JSON files without failing the action:

- uses: woeterman94/json-validator-typescript-action@v1
  with:
    folder: '.'
    fail-on-invalid: false

With this setting, invalid files are still reported in the standard output format, but the action will exit successfully instead of failing. This is useful for reporting purposes or when you want to track JSON validity without blocking workflows.

How It Works

1. The action scans the specified folder (or entire repository) for all .json files
2. Each JSON file is validated for proper syntax
3. If a global schema is provided via the schema input, all files are validated against it
4. If no global schema is provided, the action checks each JSON file for a $schema property
5. Files with a $schema property are validated against their specified schema (if it exists locally)
6. The action reports all validation errors with file paths
7. The action fails if any invalid JSON files are found

Testing

This action includes a comprehensive test suite. To run tests:

npm install
npm test

# Run with coverage
npm run test:coverage

Development

Building

npm install
npm run build
npm run package

Testing Locally

# Set environment variables for inputs
export INPUT_FOLDER="test-data/valid"
export INPUT_SCHEMA=""

# Run the action
node dist/index.js

License

MIT