Search across types in GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this GraphQL query searching across types?

Given a GraphQL schema with types Book and Author, and a search query that returns a union of these types, what will be the result of this query?

query {
  search(text: "Alice") {
    __typename
    ... on Book {
      title
      pages
    }
    ... on Author {
      name
      booksWritten
    }
  }
}

A [{"name": "Alice Walker", "booksWritten": 12}, {"title": "Alice in Wonderland", "pages": 200}]

B [{"__typename": "Author", "name": "Alice Walker", "booksWritten": 12}, {"__typename": "Book", "title": "Alice in Wonderland", "pages": 200}]

C [{"__typename": "Book", "title": "Alice in Wonderland", "pages": 200}]

D []

💡 Hint

Remember that the search query returns a union type, so you need to check the __typename to know which fields are available.

The query returns both Author and Book objects matching the text "Alice". The __typename field tells us which type each result is, so the output includes both types with their respective fields.

🧠 Conceptual

intermediate

Which GraphQL feature allows searching across multiple types in one query?

In GraphQL, how can you write a query that searches across different types like Movie and Director and returns results from both?

A Using fragments only on one type

B Using multiple separate queries for each type

C Using a union type in the schema and inline fragments in the query

D Using scalar types instead of objects

💡 Hint

Think about how to combine different types into one result list.

Union types let you combine multiple object types into one field. Inline fragments in the query let you specify fields for each type.

📝 Syntax

advanced

Identify the syntax error in this GraphQL search query across types

What is wrong with this GraphQL query that searches across Article and Author types?

query {
  search(text: "GraphQL") {
    ... on Article {
      title
      content
    }
    ... on Author
      name
      articlesCount
  }
}

A The search field must be called searchAll

B Missing __typename field in the query

C Using ... on Article instead of ... on Articles

D Missing curly braces around the Author inline fragment fields

💡 Hint

Check the syntax of inline fragments carefully.

Inline fragments require curly braces around the fields. The Author fragment is missing these braces, causing a syntax error.

❓ optimization

advanced

How to optimize a GraphQL search query across types to reduce data transfer?

You have a search query returning a union of Product and Category. How can you reduce the amount of data sent over the network?

A Request only the fields you need using inline fragments

B Remove the search filter to get fewer results

C Use a scalar type instead of a union type

D Request all fields for both types to avoid multiple queries

💡 Hint

Think about selecting only necessary data.

GraphQL lets you specify exactly which fields you want. Using inline fragments to request only needed fields reduces data size.

🔧 Debug

expert

Why does this GraphQL search query across types return an empty list?

Given this query:

query {
  search(text: "John") {
    __typename
    ... on User {
      username
    }
    ... on Post {
      title
    }
  }
}

But the result is always an empty list, even though there are users and posts with "John" in their data. What is the most likely cause?

A The search resolver does not implement searching across both User and Post types

B The query is missing the <code>id</code> field in the fragments

C The <code>__typename</code> field is causing the query to fail

D The search argument <code>text</code> is case-sensitive and "John" does not match

💡 Hint

Think about what the backend resolver does with the search argument.

If the search resolver only searches one type or is not implemented for both types, the query returns no results even if data exists.