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* Bury Best Practices, for the time being. * Bury Schema, but leave it on disk. * Introduce new Querying section. * Move "Why Apollo Server?" into "Index". * ...to be refined. * Remove no-longer-helpful "Getting Started" from "Index". cc @stubailo @evans @peggyrayzis @JakeDawkins @unicodeveloper @jbaxleyiii
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| Sending queries |
Operation names
When sending the queries and mutations in the above examples, we've used either query { ... } or mutation { ... } respectively. While this is fine, and particularly convenient when running queries by hand, it makes sense to name the operation in order to quickly identify operations during debugging or to aggregate similar operations together for application performance metrics, for example, when using Apollo Engine to monitor an API.
Operations can be named by placing an identifier after the query or mutation keyword, as we've done with HomeBookListing here:
query HomeBookListing {
getBooks {
title
}
}
Variables
In the examples above, we've used static strings as values for both queries and mutations. This is a great shortcut when running "one-off" operations, but GraphQL also provides the ability to pass variables as arguments and avoid the need for clients to dynamically manipulate operations at run-time.
By defining a map of variables on the root query or mutation operation, which are sent from the client, variables can be used (and re-used) within the types and fields themselves.
For example, with a slight change to the mutation we used in the previous step, we enable the client to pass title and author variables alongside the operation itself. We can also provide defaults for those variables for when they aren't explicitly set:
mutation HomeQuickAddBook($title: String, $author: String = "Anonymous") {
addBook(title: $title, author: $author) {
title
}
}
GraphQL clients, like Apollo Client, take care of sending the variables to the server separate from the operation itself:
{
"query": "...",
"variables": { "title": "Green Eggs and Ham", "author": "Dr. Seuss" }
}
This functionality is also supported by tools like GraphQL Playground and GraphiQL.