1/5/2024 0 Comments Graphql query json![]() ![]() The Query type is a lot like the Fruit type we've discussed, but its job is more important: it acts like the front door to a GraphQL service. And in order to send queries to a service, we need its schema to include a very special type: the Query type. The schema is our source of truth when working with a GraphQL service. The service includes this information in a document called the schema, which outlines all the things we're allowed to ask the service for. To query for the kind of fruit data that we've described, we need a GraphQL service that's set up to understand what a Fruit type is and which fields it has. How do we actually ask for data using our types and fields with GraphQL? In our case, we can have many different kinds of fruit that can be described using the same fields, even if their individual property values differ. In general, a type should define a recognizable category of things with common properties. How we define types-where we draw boundaries around the categories they work with-depends on how we want to use the data. When we need to represent a new kind of fruit, the type gives us a standard way to organize a fruit's fields and corresponding values so that we can access and use them. In GraphQL, this Fruit type is considered an Object Type. With Fruit as our type, we can see how its price could exist as one of its fields. As a type of thing in general, fruit could have many properties for us to learn about, but here we're asking for just one: the cost of the fruit, or its price. It's the subject that we want specific information for. In this example, we can imagine the type of thing we're asking about as the "fruit". Let's ask an example question-or query-to see these pieces at work. This lets us get really detailed with our request: we can ask for lots of things, or just one. Types let us define what we want information about, and fields let us specify the individual properties on the type. We use a system of types and fields to organize and write our GraphQL queries. And it just takes a few core pieces: types and fields. The "structure" part of GraphQL is what allows us to write fewer, more precise requests to get all the data we need in one go. When we write and run a GraphQL query, we're sending a structured request for data from a GraphQL API. For instance, when communicating with a GraphQL service, we use GraphQL! When working directly with a backend database, we might use something like SQL (Structured Query Language). ![]() The query language we use in a given situation depends on the resource we need to get data from. In the case of GraphQL, we can make fewer requests while receiving more data. They give the system that provides the data clear instructions about what to do, what to grab, or what to delete.ĭifferent query languages have different strengths they often solve a particular problem. These keywords have specific meaning assigned to them within the query language. Many times a language's syntax involves keywords like SELECT or mutation. Sometimes we need to include certain characters, spacing, or words. For this reason, query languages have their own syntax, or way of writing requests. When we ask for data, we need to be precise and follow specific rules so that the system understands what we're looking for. This query requires the name of the repository that we are querying for and the name of the owner as well.Query languages exist to help us ask a system or service for something in particular. In this query, we are going to query for a repository name and owner id. ![]() To get started, let’s look at a query that accepts some arguments as parameters. In GraphQL, you can use variables to reuse the same query/mutations written by the client, with different arguments. GraphQL is self-documenting, and you can browse through the complete GraphQL Schema here. What’s great about this is the documentation explorer, on the right side. On the left side of the explorer, you can define your queries and the right side displays the JSON output that comes back from the server. The GitHub explorer is a great way to write and test your queries against the API. Make sure you are signed in to your GitHub account to run the queries. To demonstrate and learn GraphQL variables, I am going to use the GitHub API that is available to the public. Getting started using GitHub’s public API To learn more about defining types in a GraphQL schema, you can read our previous post here. The two most used types are query and mutation types. If you are unsure what GraphQL queries are, I recommend reading this article first, before we get started on GraphQL variables.Ī GraphQL schema can contain more than just the scalar types. In previous blog posts, we learned about writing GraphQL queries using the GitHub API explorer. It’s essentially a query language for your API and provides a great developer experience. GraphQL has recently gained the attention of several companies. ![]()
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