GraphQL Inline Fragments

Introduction to GraphQL Inline Fragments

GraphQL inline fragments allow you to handle polymorphic types within queries. They are particularly useful when querying interfaces or unions, enabling you to specify fields for different types without needing separate queries for each type.

Understanding Polymorphism in GraphQL

Polymorphism refers to the ability of different data types to be processed through a unified interface. In GraphQL, this concept is handled using interfaces and unions. Inline fragments provide a mechanism to query fields specific to each type within an interface or union.

Using Inline Fragments in a GraphQL Query

Inline fragments are used in GraphQL queries to include type-specific fields. This is essential when querying data that could be of multiple types, such as a SearchResult that might be either a Book or a Magazine.

Let's look at an example where we query a list of search results, which could be books or magazines:

Benefits of Using Inline Fragments

Inline fragments offer several advantages:

• Reduced Complexity: Instead of writing multiple queries for different types, you can handle them within a single query.
• Improved Performance: By reducing the number of queries, you minimize the overhead associated with multiple requests.
• Flexibility: Easily accommodate changes in schema by adjusting inline fragments as needed.

When to Use Inline Fragments

Inline fragments are best used when dealing with polymorphic types, especially when:

• Querying interfaces or unions.
• Needing type-specific fields in a single query.
• Striving to keep queries DRY (Don't Repeat Yourself).

Conclusion

GraphQL inline fragments are a powerful tool for handling polymorphic types in queries. By allowing you to specify fields for different types within a single query, they provide a flexible and efficient means of working with diverse data structures.

In the next post, we'll explore GraphQL directives and how they can further enhance your queries.