GRAPHQL FRAGMENTS HOW TO
I was aware of the concept of GraphQL fragments, but nothing explaining exactly how to use them with Kontent on Gatsby.
GRAPHQL FRAGMENTS UPDATE
If I refactor the content type in Kontent then I have to update the code in multiple places. So using them means eliminating duplicated code. According to the official spec, GraphQL Fragments are 'the primary unit of composition in GraphQL.' That means theyre elemental, atomic- you cant reduce the code further down. However, when all of these pages are passing the data to the same component this seems like poor design. Basically, GraphQL Fragments help developers stick to the Dont Repeat Yourself principle. For more information, check out the detailed examples in the GraphQL documentation. Maybe this is because the philosophy behind GraphQL is very page-centric in that you request all of the information you need to render a page in a single request. Introspection is a key concept of the GraphQL standard, since it provides a mechanism for getting the actual query capabilities and limits of an API. A GraphQL Fragment is a reusable unit of a GraphQL query, which creates a shared piece of query logic. You can think of it as functions in programming languages, that are reusable units. Fragments are a very powerful and useful feature in GraphQL, and if you do not know what fragments are you can read more here. This summary needs fields from the article type and the standard pattern that I see is for each page/template to have those fields in their queries. A GraphQL fragment lets you build multiple fields, and include them in multiple queries. I have an article summary component which is used in multiple places (the index page, journal template and tag template). It is mentioned on the Gatsby documentation but the example isn't clear and does not explain the benefits well.įirst let me set up the problem with an example from this website. It is one of those things that just seems like an obviously strong pattern, but I couldn't find it clearly advocated anywhere. This is a quick guide on a pattern for using fragments inside your React components to avoid duplication. Then, you pass your newly configured cache to ApolloClient to complete the process.The use of GraphQL in Gatsby brings many advantages, but it can lead to duplication of query fields across pages and templates. Use possibleTypes.json to configure your cache during construction.Or use the plugin fragment-matcher for graphql-codegen and configure it for apollo client 3. Read the documentation about how to extract possibleTypes automatically using an introspection query. Query your server / schema to obtain the necessary information about unions and interfaces and write it to a file.We recommend setting up a build step that extracts the necessary information from the schema into a JSON file, where it can be imported from when constructing the cache. A common example of this is using an id field to perform authorization checks an initial query might not request the id field, but your rule still needs it to check if the. Fragments can be nested inside fragments, but no cycles are allowed in such cases. Fragments allow for the reuse of common repeated selections of fields, reducing duplicated text in the DQL documents. The section below explains how to pass the necessary schema knowledge to the Apollo Client cache so unions and interfaces can be accurately matched and results validated before writing them into the store. Fragments If your GraphQL server connects to another GraphQL server, it might happen that your rules require additional data that user doesn't have to request by default. The fragment keyword lets you define new fragments that can be referenced in a query, per the Fragments section of the GraphQL specification. To inform the cache store about these polymorphic relationships, you need to pass possibleTypes option to InMemor圜ache below. This works in most cases, but it also means that Apollo Client cannot check the server response for you, and it cannot tell you when you're manually writing invalid data into the store using update, updateQuery, writeQuery, etc. By default, Apollo Client's cache will use a heuristic fragment matcher, which assumes that a fragment matched if the result included all the fields in its selection set, and didn't match when any field was missing. Both Jedi and Droid are possible concrete types of Character, but on the client there is no way to know that without having some information about the schema. In the query above, allPeople returns a result of type Character.
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