Arguments and Variables

What you'll walk away with

Explain the core ideas behind Arguments and Variables
Run the sample GraphQL query or code and verify its output
Apply the technique correctly to the Tutorial Platform and production scenarios

Build the mental model

Every GraphQL field can accept arguments — syntax like `tutorial(id: "42")` parameterizes a single field. Instead of hardcoding values in the query string, declare a variable such as `$id: ID!` and send its value separately as a variables JSON object per request; this lets client code reuse the same query string and reduces injection risk. Default values (`$includeAuthor: Boolean = true`) and the `@include`/`@skip` directives let you conditionally include fields.

Connect it to a real scenario

The Tutorial Platform frontend reuses a single `TutorialById` query string across many ids by changing only the variables. When a mobile client does not need the author bio, it sends `$includeAuthor: false`, and the `@include(if: $includeAuthor)` directive skips the author sub-selection.

Field arguments parameterize individual fields
Variables let you reuse one query string safely
@include/@skip directives make field inclusion conditional

Try the working example

graphql

query TutorialById($id: ID!, $includeAuthor: Boolean = true) {
  tutorial(id: $id) {
    title
    summary
    author @include(if: $includeAuthor) {
      name
    }
  }
}

# variables: { "id": "42", "includeAuthor": false }

You should see

You can write fields with arguments and a reusable, variable-based query.

5-minute try-it

Write a `tutorials(difficulty: $difficulty)` query using a `$difficulty: Difficulty` variable, and run it with two different variable values.

One important caution

Do not concatenate values directly into the query string — user input there can create injection and caching problems. Use variables instead.

GraphQL — Queries and Mutations — GraphQL

Easy traps

Do not concatenate values directly into the query string — user input there can create injection and caching problems. Use variables instead.
Validate sample queries and mutations on a local or test server with recoverable data before applying them to production.

Exercise

Write a `tutorials(difficulty: $difficulty)` query using a `$difficulty: Difficulty` variable, and run it with two different variable values.

You'll know it worked when: You can write fields with arguments and a reusable, variable-based query.