Delete mutation pattern in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a delete mutation for removing a user by ID.

GraphQL

mutation DeleteUser($id: ID!) {
  deleteUser(id: [1]) {
    id
    name
  }
}

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

AuserId

Bid

CID

DdeleteId

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name than declared in the mutation signature.

Confusing the type name 'ID' with the variable name.

The variable name used in the mutation argument must match the declared variable $id.

2fill in blank

medium

Complete the code to specify the return fields after deleting a post.

GraphQL

mutation DeletePost($postId: ID!) {
  deletePost(id: $postId) {
    [1]
  }
}

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

Atitle content

Bid content

Cid title

DpostId title

Attempts:

3 left

💡 Hint

Common Mistakes

Returning fields that do not exist on the deleted object.

Using variable names instead of field names.

After deletion, returning the id and title helps confirm which post was deleted.

3fill in blank

hard

Fix the error in the delete mutation by completing the argument name correctly.

GraphQL

mutation RemoveComment($commentId: ID!) {
  deleteComment([1]: $commentId) {
    id
  }
}

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

AcommentId

Bid

CcommentID

Dcomment_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect casing in argument names.

Using underscores instead of camelCase.

The argument name must exactly match the expected argument in the schema, which is commentId.

4fill in blank

hard

Fill both blanks to complete the delete mutation and specify the return fields.

GraphQL

mutation DeleteProduct($[1]: ID!) {
  deleteProduct(id: $[2]) {
    id
    name
  }
}

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

AproductId

BproductID

Cid

DprodId

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in declaration and usage.

Using uppercase letters inconsistently.

The variable name must be consistent in both the declaration and usage: productId.

5fill in blank

hard

Fill all three blanks to write a delete mutation for removing an order and returning its ID and status.

GraphQL

mutation DeleteOrder($[1]: ID!) {
  deleteOrder([2]: $[3]) {
    id
    status
  }
}

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

AorderId

BorderID

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing orderID and orderId.

Using id instead of the expected argument name.

The variable name orderId must be consistent in declaration and usage. The argument name is orderId.

Practice

1.

What is the main purpose of a delete mutation in GraphQL?

easy

A. To update existing data in the database

B. To add new data to the database

C. To remove data from the database using an identifier

D. To fetch data without modifying it

Solution

1. Step 1: Understand the role of delete mutations

   Delete mutations are designed to remove data entries, usually by specifying an ID or unique key.

2. Step 2: Compare with other mutation types

   Add mutations create data, update mutations modify data, and queries fetch data without changes.

3. Final Answer:

   To remove data from the database using an identifier -> Option C

4. Quick Check:

   Delete mutation = remove data [OK]

Hint: Delete mutations always remove data by ID [OK]

Common Mistakes:

• Confusing delete with add or update mutations
• Thinking delete fetches data
• Assuming delete mutations do not require an identifier

2.

Which of the following is the correct syntax for a GraphQL delete mutation to remove a user by ID?

mutation {
  deleteUser(id: "123") {
    success
    message
  }
}

easy

A. mutation { deleteUser(id: "123") { success message } }

B. mutation { deleteUser { id: "123" success message } }

C. mutation { deleteUser(id: 123) { success message } }

D. mutation { deleteUser(id: "123") success message }

Solution

1. Step 1: Check argument placement and syntax

   The ID must be passed as an argument inside parentheses with quotes for string: id: "123".

2. Step 2: Verify the selection set braces

   The fields to return (success, message) must be inside braces after the mutation call.

3. Final Answer:

   mutation { deleteUser(id: "123") { success message } } -> Option A

4. Quick Check:

   Correct syntax = mutation { deleteUser(id: "123") { success message } } [OK]

Hint: Arguments go inside parentheses, fields inside braces [OK]

Common Mistakes:

• Passing id without quotes for string
• Placing fields outside braces
• Misplacing argument inside selection set

3.

Given the following delete mutation and response, what is the value of success?

mutation {
  deletePost(id: "abc") {
    success
    message
  }
}

Response:

{
  "data": {
    "deletePost": {
      "success": true,
      "message": "Post deleted successfully"
    }
  }
}

medium

A. false

B. true

C. null

D. undefined

Solution

1. Step 1: Read the mutation response carefully

   The response shows the success field inside deletePost as true.

2. Step 2: Understand the meaning of success

   A true value means the deletion was successful.

3. Final Answer:

   true -> Option B

4. Quick Check:

   Response success = true [OK]

Hint: Check response JSON for success field value [OK]

Common Mistakes:

• Confusing success with message content
• Assuming success is false without checking response
• Ignoring JSON structure

4.

Identify the error in this delete mutation:

mutation {
  deleteComment(commentId: 456) {
    success
    message
  }
}

medium

A. Missing quotes around the commentId value

B. Missing selection set braces

C. Incorrect mutation keyword

D. Using wrong field names in response

Solution

1. Step 1: Check argument data type

   The commentId is likely a string and should be enclosed in quotes: "456".

2. Step 2: Verify mutation syntax

   The mutation keyword and selection set braces are correct; field names are valid.

3. Final Answer:

   Missing quotes around the commentId value -> Option A

4. Quick Check:

   String IDs need quotes [OK]

Hint: String IDs must be in quotes in mutations [OK]

Common Mistakes:

• Passing string IDs without quotes
• Omitting braces around fields
• Using wrong mutation keyword

5.

You want to delete multiple users by their IDs in one mutation call. Which approach correctly applies the delete mutation pattern?

Options:

1. mutation { deleteUsers(ids: ["1", "2", "3"]) { success message } }
2. mutation { deleteUser(id: "1") { success message } deleteUser(id: "2") { success message } }
3. mutation { deleteUser(id: "1") { success message } }
4. mutation { deleteUsers(ids: "1,2,3") { success message } }

hard

A. Call deleteUser mutation multiple times in one request

B. Pass IDs as a comma-separated string in deleteUsers(ids: "1,2,3")

C. Delete only one user at a time with deleteUser(id: "1")

D. Use a single mutation with an array of IDs: deleteUsers(ids: ["1", "2", "3"])

Solution

1. Step 1: Understand batch deletion

   To delete multiple users at once, the mutation must accept an array of IDs.

2. Step 2: Evaluate options

   Use a single mutation with an array of IDs: deleteUsers(ids: ["1", "2", "3"]) correctly passes an array of strings. Call deleteUser mutation multiple times in one request tries multiple mutations in one call, which is invalid syntax. Delete only one user at a time with deleteUser(id: "1") deletes only one user. Pass IDs as a comma-separated string in deleteUsers(ids: "1,2,3") passes a string instead of an array.

3. Final Answer:

   Use a single mutation with an array of IDs: deleteUsers(ids: ["1", "2", "3"]) -> Option D

4. Quick Check:

   Batch delete uses array of IDs [OK]

Hint: Batch deletes use array arguments, not comma strings [OK]

Common Mistakes:

• Trying multiple mutations in one call
• Passing IDs as comma string instead of array
• Assuming single delete mutation handles multiple IDs