Partial success responses in GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

Partial success with GraphQL query

Given a GraphQL query that requests user data and their posts, if the posts field fails but user data is returned successfully, what will the response contain?

GraphQL

query {
  user(id: "123") {
    id
    name
    posts {
      id
      title
    }
  }
}

A { "data": null, "errors": [{ "message": "Failed to fetch posts" }] }

B { "errors": [{ "message": "Failed to fetch posts" }] }

C { "data": { "user": { "id": "123", "name": "Alice", "posts": null } }, "errors": [{ "message": "Failed to fetch posts" }] }

D { "data": { "user": null }, "errors": [{ "message": "Failed to fetch posts" }] }

💡 Hint

Partial success responses include data where possible and errors for failed parts.

GraphQL returns partial data when some fields fail, setting those fields to null and including errors describing the failure.

🧠 Conceptual

intermediate

Understanding partial success error locations

In a GraphQL partial success response, where is the error location information found and what does it indicate?

A In the errors array, under the 'locations' field, indicating the position in the query where the error occurred.

B In the data field, marking the exact field that failed with an error message.

C In the HTTP headers, specifying which part of the query failed.

D In the extensions field of the response, describing the error severity.

💡 Hint

Errors array contains detailed info about failures.

The 'locations' field in each error shows the line and column in the query where the error happened, helping clients identify the failed part.

📝 Syntax

advanced

Identify the invalid partial success response

Which of the following GraphQL partial success responses is syntactically invalid?

A { "data": { "user": { "id": "1", "posts": null } }, "errors": [{ "message": "Posts not found", "locations": { "line": 3, "column": 5 } }] }

B { "data": { "user": { "id": "1", "posts": null } }, "errors": [{ "message": "Posts not found" }] }

C { "data": { "user": { "id": "1", "posts": null } }, "errors": [{ "message": "Posts not found", "locations": [{ "line": 3, "column": 5 }] }] }

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💡 Hint

Check the type of the 'locations' field in errors.

The 'locations' field must be an array of objects, not a single object.

❓ optimization

advanced

Optimizing partial success error handling in clients

Which approach best optimizes a client application to handle GraphQL partial success responses efficiently?

A Retry the entire query automatically when any error appears in the response.

B Process the 'data' field normally and separately handle the 'errors' array to update UI only for failed fields.

C Stop processing the response if any errors are present, ignoring partial data.

D Ignore the 'errors' array and display all data fields as if no errors occurred.

💡 Hint

Partial success means some data is usable despite errors.

Clients should use available data and handle errors gracefully to update only affected parts of the UI.

🔧 Debug

expert

Debugging inconsistent partial success responses

A GraphQL server sometimes returns partial success responses with missing 'errors' array even when some fields are null due to failure. What is the most likely cause?

A The network is dropping the 'errors' array during transmission.

B The client is filtering out the 'errors' array before displaying the response.

C The GraphQL specification allows omitting errors if data is present.

D The server's error handling middleware is not attaching errors properly to the response.

💡 Hint

Partial success requires errors to explain null fields.

If errors are missing, the server likely failed to include them, causing incomplete partial success responses.