Context-based authentication in GraphQL - Mini Project: Build & Apply

Context-based Authentication with GraphQL

📖 Scenario: You are building a simple GraphQL API for a small online store. The API needs to authenticate users based on a context token to allow access to user-specific data.

🎯 Goal: Build a GraphQL schema and resolver setup that uses context-based authentication to return user data only if the correct token is provided.

📋 What You'll Learn

Create a GraphQL schema with a User type and a Query type with a me field

Add a context object that contains a token string

Implement a resolver for me that checks the token in context and returns user data if the token matches

Return null if the token is missing or invalid

💡 Why This Matters

🌍 Real World

Context-based authentication is used in real APIs to control access to user data based on tokens or session info.

💼 Career

Understanding how to use context in GraphQL for authentication is essential for backend developers building secure APIs.

1

Define the GraphQL schema

Create a GraphQL schema string called typeDefs that defines a User type with fields id (ID!), name (String!), and a Query type with a me field returning User.

GraphQL

# Your code here

Hint

Define the schema as a template string with the required types and fields.

2

Add context with token

Create a variable called context that is an object with a token property set to the string "secret-token-123".

GraphQL

const typeDefs = `
  type User {
    id: ID!
    name: String!
  }

  type Query {
    me: User
  }
`;

# Your code here

Hint

Create a simple object with the token string.

3

Implement the resolver with token check

Create a resolvers object with a Query field containing a me function. This function takes parent, args, and ctx parameters and returns an object { id: "1", name: "Alice" } only if ctx.token equals "secret-token-123". Otherwise, return null.

GraphQL

const typeDefs = `
  type User {
    id: ID!
    name: String!
  }

  type Query {
    me: User
  }
`;

const context = { token: "secret-token-123" };

# Your code here

Hint

Use a simple if statement inside the resolver to check the token.

4

Complete the GraphQL server setup

Create a variable called server that is an instance of ApolloServer initialized with typeDefs, resolvers, and a context function returning the context object.

GraphQL

Hint

Use new ApolloServer with the correct options.