Delete mutation pattern in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of a delete mutation in GraphQL?

A delete mutation is used to remove data from the database by specifying which item to delete, usually by its unique identifier.

beginner

In a delete mutation, why do we usually pass an ID as an argument?

Passing an ID ensures the mutation knows exactly which record to delete, avoiding accidental removal of multiple or wrong records.

intermediate

What should a delete mutation typically return?

It usually returns the deleted item's ID or a confirmation message to show the deletion was successful.

beginner

Show a simple example of a delete mutation in GraphQL.

mutation DeleteUser($id: ID!) { deleteUser(id: $id) { id } }

intermediate

Why is it important to handle errors in delete mutations?

Handling errors helps inform the user if the item was not found or if deletion failed, improving user experience and data safety.

What argument is commonly required in a delete mutation?

A New data to update

B ID of the item to delete

C List of all items

D User password

Delete mutations need the ID to identify which item to remove.

What does a delete mutation usually return?

A The entire database

B All remaining items

C The deleted item's ID or confirmation

D Nothing at all

Returning the deleted item's ID confirms the deletion was successful.

Which GraphQL operation type is used for deleting data?

A mutation

B query

C subscription

D fragment

Mutations are used to change data, including deletions.

Why should you handle errors in delete mutations?

A To inform users if deletion fails

B To speed up the deletion

C To add new data

D To change the schema

Error handling improves user experience by showing if deletion did not work.

Which of these is a valid delete mutation example?

A subscription { deleteUser(id: "123") { id } }

B query { deleteUser(id: "123") { id } }

C mutation { addUser(name: "John") { id } }

D mutation { deleteUser(id: "123") { id } }

Delete operations must be mutations and include the ID of the item to delete.

Explain the steps and key parts of a delete mutation pattern in GraphQL.

Think about how you tell the server what to delete and how it confirms deletion.

Describe why it is important to return data after a delete mutation and what kind of data is usually returned.

Consider how the client knows the deletion worked.

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