Queries, Variables and Fragments

Arguments

Fields can take arguments to filter or shape results:

query {
  posts(first: 5, category: "tech") {
    title
  }
}

Variables

Hard-coding values into a query string is fragile. Declare variables and pass them separately – the query becomes reusable and safe from injection:

query GetUser($id: ID!) {
  user(id: $id) {
    name
    email
  }
}

// variables sent alongside the query
{ "id": "1" }

Fragments

A fragment is a named, reusable set of fields – handy when several queries need the same shape:

fragment PostFields on Post {
  id
  title
  createdAt
}

query {
  featured { ...PostFields }
  recent   { ...PostFields }
}

Aliases

Ask for the same field twice with different arguments by aliasing them:

query {
  today: posts(date: "2026-09-15") { title }
  yesterday: posts(date: "2026-09-14") { title }
}

Subscriptions (real-time)

Alongside Query and Mutation, GraphQL has Subscription for live data pushed over a WebSocket – e.g. a chat message stream. Clients subscribe and receive updates as they happen.

Key points

• Fields take arguments to filter and shape results.
• Use variables ($id) to make queries reusable and safe.
• Fragments reuse a set of fields across queries.
• Aliases fetch the same field multiple ways; subscriptions deliver real-time data.