GraphQL body in Postman

Introduction

GraphQL body lets you send queries or mutations to a GraphQL server in a structured way. It helps you ask for exactly the data you want.

When you want to test a GraphQL API endpoint in Postman.

When you need to send a query to get specific data from a server.

When you want to send a mutation to change data on the server.

When you want to test how the server responds to different GraphQL requests.

When you want to check error handling for invalid GraphQL queries.

Syntax

Postman

{
  "query": "GraphQL query or mutation string",
  "variables": { /* optional variables object */ }
}

The query field contains the GraphQL query or mutation as a string.

The variables field is optional and holds any variables your query uses.

Examples

A simple query asking for a user's name and email by ID.

Postman

{
  "query": "{ user(id: \"1\") { name email } }"
}

A mutation to add a new user named Alice and get back her id and name.

Postman

{
  "query": "mutation { addUser(name: \"Alice\") { id name } }"
}

A query using variables to get user data for id 2.

Postman

{
  "query": "query getUser($id: ID!) { user(id: $id) { name email } }",
  "variables": { "id": "2" }
}

Sample Program

This GraphQL body queries a book by its ID 101, asking for its title and author.

Postman

{
  "query": "query getBook($bookId: ID!) { book(id: $bookId) { title author } }",
  "variables": { "bookId": "101" }
}

Important Notes

Always use double quotes for JSON keys and string values in the GraphQL body.

Variables help keep queries clean and reusable.

GraphQL body must be sent as raw JSON with Content-Type set to application/json in Postman.

Summary

GraphQL body is a JSON object with a query string and optional variables.

It lets you send precise queries or mutations to a GraphQL API.

Use variables to make queries flexible and easier to test.

Practice

1. What is the main purpose of the query field in a GraphQL body when testing with Postman?

easy

A. To list all available API endpoints

B. To define the HTTP headers for the request

C. To set the URL of the GraphQL endpoint

D. To specify the exact data you want to fetch or mutate from the API

Solution

1. Step 1: Understand the role of the query field

   The query field contains the GraphQL query or mutation string that tells the API exactly what data to return or change.

2. Step 2: Differentiate from other request parts

   Headers and URLs are set elsewhere in Postman; the query field is specifically for the GraphQL operation.

3. Final Answer:

   To specify the exact data you want to fetch or mutate from the API -> Option D

4. Quick Check:

   GraphQL query = data request [OK]

Hint: Remember: query means what data you want [OK]

Common Mistakes:

• Confusing query with HTTP headers
• Trying to put URL or endpoint inside query
• Leaving query empty or missing

2. Which of the following is the correct minimal structure of a GraphQL body in Postman?

easy

A. { "query": "{ user { id name } }" }

B. { "url": "https://api.example.com/graphql" }

C. { "headers": { "Content-Type": "application/json" } }

D. { "variables": { "id": 1 } }

Solution

1. Step 1: Identify the required fields in a GraphQL body

   The minimal GraphQL body must have a query field with a valid query string.

2. Step 2: Check each option

   { "query": "{ user { id name } }" } correctly shows a JSON object with a query string. The structures with "url" and "headers" are for other parts of the Postman request, not the body. { "variables": { "id": 1 } } only has variables without a query, which is invalid.

3. Final Answer:

   { "query": "{ user { id name } }" } -> Option A

4. Quick Check:

   GraphQL body needs query string [OK]

Hint: GraphQL body always needs a query string [OK]

Common Mistakes:

• Putting URL or headers inside the GraphQL body
• Sending variables without a query
• Using invalid JSON format

3. Given this GraphQL body in Postman:

{
  "query": "query getUser($id: ID!) { user(id: $id) { name email } }",
  "variables": { "id": "123" }
}

What data will the API return if user 123 exists?

medium

A. Only the user's ID

B. The user's name and email fields

C. An error because variables are not allowed

D. All users' names and emails

Solution

1. Step 1: Understand the query and variables

   The query requests name and email of a user with a specific id passed as a variable.

2. Step 2: Interpret the expected response

   Since id is set to "123", the API will return the name and email of user 123 if they exist.

3. Final Answer:

   The user's name and email fields -> Option B

4. Quick Check:

   Variables filter data = user 123 info [OK]

Hint: Variables customize queries to fetch specific data [OK]

Common Mistakes:

• Ignoring variables and expecting all users
• Thinking variables cause errors in GraphQL
• Expecting ID field in response without requesting it

4. You send this GraphQL body in Postman:

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

The API returns an error about missing variables. What is the fix?

medium

A. Add a variables field with the required id value

B. Remove the $id variable from the query

C. Change the query to a mutation

D. Add HTTP headers for authentication

Solution

1. Step 1: Identify the cause of the error

   The query requires a variable $id but no variables field was sent, so the API complains about missing input.

2. Step 2: Fix by adding variables

   Include a variables JSON object with the id value, e.g., { "id": "123" }, to satisfy the query requirement.

3. Final Answer:

   Add a variables field with the required id value -> Option A

4. Quick Check:

   Variables must match query parameters [OK]

Hint: Always send variables if query requires them [OK]

Common Mistakes:

• Forgetting to send variables when query uses them
• Trying to remove variables from query without adjusting logic
• Assuming authentication fixes variable errors

5. You want to test a GraphQL mutation to update a user's email using variables in Postman. Which GraphQL body correctly uses variables for this mutation?

hard

A. { "query": "mutation updateUser { updateUser(id: $id, email: $email) { id email } }", "variables": { "id": 456, "email": "[e-mail]" } }

B. { "query": "mutation { updateUser(id: 456, email: \"[e-mail]\") { id email } }" }

C. { "query": "mutation updateUser($id: ID!, $email: String!) { updateUser(id: $id, email: $email) { id email } }", "variables": { "id": "456", "email": "[e-mail]" } }

D. { "query": "mutation updateUser($id, $email) { updateUser(id: $id, email: $email) { id email } }", "variables": { "id": "456", "email": "[e-mail]" } }

Solution

1. Step 1: Check variable declarations in mutation

   Variables must be declared with types and exclamation marks for required fields, e.g., $id: ID!, $email: String!.

2. Step 2: Verify variables usage and JSON format

   { "query": "mutation updateUser($id: ID!, $email: String!) { updateUser(id: $id, email: $email) { id email } }", "variables": { "id": "456", "email": "[e-mail]" } } correctly declares variables with types and passes matching variables in JSON. { "query": "mutation { updateUser(id: 456, email: \"[e-mail]\") { id email } }" } hardcodes values without variables. { "query": "mutation updateUser { updateUser(id: $id, email: $email) { id email } }", "variables": { "id": 456, "email": "[e-mail]" } } misses variable types. { "query": "mutation updateUser($id, $email) { updateUser(id: $id, email: $email) { id email } }", "variables": { "id": "456", "email": "[e-mail]" } } misses exclamation marks in variable types.

3. Final Answer:

   { "query": "mutation updateUser($id: ID!, $email: String!) { updateUser(id: $id, email: $email) { id email } }", "variables": { "id": "456", "email": "[e-mail]" } } -> Option C

4. Quick Check:

   Declare variables with types and pass matching values [OK]

Hint: Declare variables with types and pass matching JSON values [OK]

Common Mistakes:

• Omitting variable types or exclamation marks
• Using variables without declaring them
• Hardcoding values instead of using variables