Your First Query

The Version Query

Every UDL server includes a built-in version query. This is the simplest way to verify your server is running:

query {
  version
}

This returns the current UDL version string.

Using cURL

Test the server from your terminal:

curl http://localhost:4000/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ version }"}'

You should see a response like:

{
  "data": {
    "version": "1.0.0"
  }
}

Using GraphiQL

For an interactive experience, open your browser to:

http://localhost:4000/graphiql

GraphiQL is a built-in IDE for exploring and testing GraphQL queries. Type the version query in the left panel and click the play button (or press Ctrl+Enter).

Understanding the Response

GraphQL responses always follow this structure:

{
  "data": {
    // Query results here
  },
  "errors": [
    // Any errors here (only present if errors occurred)
  ]
}

The data field contains your query results, with keys matching your query field names. The errors field only appears when something goes wrong.

Next Steps

• Exploring GraphQL - Learn GraphQL basics with the GraphiQL IDE
• Using Plugins - Add data sources to your server