GraphQL was designed to handle data from multiple sources, making it a powerful tool for building complex applications that rely on multiple data sources. Here are some ways you can use GraphQL to fetch data from multiple sources:
Using GraphQL's built-in resolver functions: One of the key features of GraphQL is its ability to use resolver functions to fetch data from multiple sources. You can define a resolver function for each field in your schema, and use these functions to fetch data from different sources. For example, you could define a resolver function that fetches data from a REST API, and another resolver function that fetches data from a database.
Using GraphQL federation: GraphQL federation is a feature that allows you to combine multiple GraphQL APIs into a single, unified API. With federation, you can create a single schema that spans multiple services, and use GraphQL's built-in query stitching to fetch data from each service. This can be useful if you have multiple microservices that expose different parts of your data.
Using GraphQL schema stitching: Similar to federation, schema stitching allows you to combine multiple GraphQL APIs into a single, unified API. However, schema stitching is not limited to GraphQL APIs - you can also use it to combine GraphQL APIs with other types of APIs, such as REST APIs. With schema stitching, you can create a single schema that spans multiple data sources, and use resolver functions to fetch data from each source.
Using GraphQL batched queries: Another way to fetch data from multiple sources with GraphQL is to use batched queries. Batched queries allow you to send multiple queries to different data sources in a single HTTP request, and receive the results in a single response. This can be useful if you have multiple data sources that you want to query at the same time.
Overall, GraphQL provides many ways to fetch data from multiple sources, and the best approach will depend on the specific needs of your application. However, with its powerful resolver functions, federation, schema stitching, and batched queries, GraphQL is well-suited for building applications that rely on multiple data sources.