Why mutations modify data in GraphQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a mutation that adds a new user with a name.

GraphQL

type Mutation { addUser(name: String!): [1] }

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A: User

B{ id: ID, name: String }

C-> User

D!

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!' after the mutation name instead of after the argument type.

Using '->' which is not valid GraphQL syntax.

Trying to define fields inside the mutation signature.

The mutation must specify the return type after the colon. Here, : User means the mutation returns a User object.

2fill in blank

medium

Complete the mutation resolver function to update a user's name by ID.

GraphQL

updateUser: (parent, args, context) => { return context.db.users.[1](args.id, args.name); }

Drag options to blanks, or click blank then click option'

Aupdate

BupdateName

CupdateUserName

Dfind

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'find' which only retrieves data.

Using made-up method names not defined in the context.

Using 'updateName' which is not a standard method.

The correct method to modify user data is typically called update. It updates the user with the given ID and new name.

3fill in blank

hard

Fix the error in the mutation resolver that tries to delete a user but returns nothing.

GraphQL

deleteUser: (parent, args, context) => { context.db.users.delete(args.id); return [1]; }

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Aargs.id

Btrue

Cnull

Dcontext.db.users.find(args.id)

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the deleted user's ID which no longer exists.

Returning true which is not a User object.

Trying to find the user after deletion which returns nothing.

After deleting, returning null is common to indicate no user object is returned.

4fill in blank

hard

Complete the code to complete the mutation that creates a post and returns its ID and title.

GraphQL

type Mutation { createPost(title: String!, content: String!): [1] { id, title } }

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APost

BUser

C:

D,

Attempts:

3 left

💡 Hint

Common Mistakes

Using ':' instead of ',' between fields.

Returning 'User' instead of 'Post'.

Omitting the comma between fields.

The mutation returns a Post type. Inside the selection set, fields are separated by commas, so , is correct.

5fill in blank

hard

Fill all three blanks to write a mutation resolver that adds a comment and returns the comment text if the content length is greater than 0.

GraphQL

addComment: (parent, args, context) => { if (args.content.[3] [1] 0) { return { text: args.[2] }; } else { return null; } }

Drag options to blanks, or click blank then click option'

A>

Bcontent

Clength

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the condition.

Using 'text' instead of 'content' for the argument field.

Using 'length' as a field name instead of a property.

The condition checks if args.content.length is greater than 0. Then it returns an object with the text field set to args.content.