Update mutation pattern in GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the result of this update mutation?

Given the following GraphQL mutation to update a user's email, what will be the returned data?

GraphQL

mutation {
  updateUser(id: "123", input: {email: "[e-mail]"}) {
    id
    name
    email
  }
}

A { "data": { "updateUser": null } }

B { "data": { "updateUser": { "id": "123", "name": "Alice", "email": "[e-mail]" } } }

C { "errors": [ { "message": "User not found" } ] }

D { "data": { "updateUser": { "id": "123", "name": "Alice", "email": "[e-mail]" } } }

💡 Hint

Consider what the mutation is intended to do and what fields it returns.

The mutation updates the user's email and returns the updated user data including the new email.

📝 Syntax

intermediate

Identify the syntax error in this update mutation

Which option correctly fixes the syntax error in this GraphQL update mutation?

GraphQL

mutation {
  updateUser(id: "123", input: {email: "[e-mail]" ) {
    id
    email
  }
}

A

mutation {
  updateUser(id: "123", input: {email: [e-mail]}) {
    id
    email
  }
}

B

mutation {
  updateUser(id: "123", input: email: "[e-mail]") {
    id
    email
  }
}

C

mutation {
  updateUser(id: "123", input: {email: "[e-mail]"}) {
    id
    email
  }
}

D

mutation {
  updateUser(id: "123", input: {email: "[e-mail]"} {
    id
    email
  }
}

💡 Hint

Check for matching brackets and correct input object syntax.

Option C correctly closes the input object with a closing brace and parenthesis.

❓ optimization

advanced

Optimize this update mutation for minimal data transfer

You want to update only the user's phone number and receive only the updated phone number in response. Which mutation is best?

GraphQL

mutation {
  updateUser(id: "123", input: {phone: "[phone]"}) {
    id
    name
    email
    phone
  }
}

A

mutation {
  updateUser(id: "123", input: {phone: "[phone]"}) {
    id
    name
    email
    phone
  }
}

B

mutation {
  updateUser(id: "123", input: {phone: "[phone]"}) {
    id
    phone
  }
}

C

mutation {
  updateUser(id: "123", input: {phone: "[phone]"}) {
    id
    name
    phone
  }
}

D

mutation {
  updateUser(id: "123", input: {phone: "[phone]"}) {
    phone
  }
}

💡 Hint

Request only the fields you need to reduce data size.

Option D requests only the updated phone field, minimizing data transfer.

🔧 Debug

advanced

Why does this update mutation fail with an error?

Given this mutation, why does it return an error?

GraphQL

mutation {
  updateUser(input: {email: "[e-mail]"}) {
    id
    email
  }
}

A The mutation is missing the required 'id' argument to identify which user to update.

B The input object is incorrectly formatted; it should be a list.

C The mutation is missing a selection set inside the input object.

D The mutation should use 'updateUsers' instead of 'updateUser'.

💡 Hint

Check the required arguments for update mutations.

Update mutations typically require an identifier to specify which record to update.

🧠 Conceptual

expert

What is the main advantage of using input types in update mutations?

Why do GraphQL update mutations commonly use input types for the data to update?

A Input types allow grouping multiple fields into a single argument, improving clarity and validation.

B Input types automatically update all fields in the database without specifying them.

C Input types make the mutation run faster by caching the data.

D Input types are required to use subscriptions with mutations.

💡 Hint

Think about how input types help organize mutation arguments.

Input types group related fields and enable schema validation, making mutations clearer and safer.