A typed GraphQL client library for Rust.
- Precise types for query variables and responses.
- Supports GraphQL fragments, objects, unions, inputs, enums, custom scalars and input objects.
- Works in the browser (WebAssembly).
- Subscriptions support (serialization-deserialization only at the moment).
- Copies documentation from the GraphQL schema to the generated Rust code.
- Arbitrary derives on the generated responses.
- Arbitrary custom scalars.
- Supports multiple operations per query document.
- Supports setting GraphQL fields as deprecated and having the Rust compiler check their use.
- web client for boilerplate-free API calls from browsers.
-
If you are not familiar with GraphQL, the official website provides a very good and comprehensive introduction.
-
Once you have written your query (most likely in something like graphiql), save it in a
.graphql
file in your project. -
In order to provide precise types for a response, graphql_client needs to read the query and the schema at compile-time.
To download the schema, you have multiple options. This projects provides a CLI, but there are also more mature tools like apollo-cli. It does not matter which one you use, the resulting
schema.json
is the same. -
We now have everything we need to derive Rust types for our query. This is achieved through a procedural macro, as in the following snippet:
extern crate serde; #[macro_use] extern crate serde_derive; #[macro_use] extern crate graphql_client; // The paths are relative to the directory where your `Cargo.toml` is located. // Both json and the GraphQL schema language are supported as sources for the schema #[derive(GraphQLQuery)] #[graphql( schema_path = "tests/unions/union_schema.graphql", query_path = "tests/unions/union_query.graphql", )] pub struct MyQuery;
The
derive
will generate a module namedmy_query
in this example - the name is the struct's name, but in snake case.That module contains all the struct and enum definitions necessary to deserialize a response to that query.
The root type for the response is named
ResponseData
. The GraphQL response will take the form of aResponse<ResponseData>
(the Response type is always the same).The module also contains a struct called
Variables
representing the variables expected by the query.
-
We now need to create the complete payload that we are going to send to the server. For convenience, the GraphQLQuery trait, is implemented for the struct under derive, so a complete query body can be created this way:
extern crate failure; #[macro_use] extern crate graphql_client; extern crate reqwest; use graphql_client::{GraphQLQuery, Response}; #[derive(GraphQLQuery)] #[graphql( schema_path = "tests/unions/union_schema.graphql", query_path = "tests/unions/union_query.graphql", response_derives = "Debug", )] pub struct MyQuery; fn perform_my_query(variables: my_query::Variables) -> Result<(), failure::Error> { // this is the important line let request_body = MyQuery::build_query(variables); let client = reqwest::Client::new(); let mut res = client.post("/graphql").json(&request_body).send()?; let response_body: Response<my_query::ResponseData> = res.json()?; println!("{:#?}", response_body); Ok(()) }
A complete example using the GitHub GraphQL API is available, as well as sample rustdoc output.
The generated response types always derive serde::Deserialize
but you may want to print them (Debug
), compare them (PartialEq
) or derive any other trait on it. You can achieve this with the response_derives
option of the graphql
attribute. Example:
#[macro_use]
extern crate graphql_client;
#[derive(GraphQLQuery)]
#[graphql(
schema_path = "tests/unions/union_schema.graphql",
query_path = "tests/unions/union_query.graphql",
response_derives = "Serialize,PartialEq",
)]
struct SearchQuery;
The generated code will reference the scalar types as defined in the server schema. This means you have to provide matching rust types in the scope of the struct under derive. It can be as simple as declarations like type Email = String;
. This gives you complete freedom on how to treat custom scalars, as long as they can be deserialized.
The generated code has support for @deprecated
field annotations. You can configure how deprecations are handled via the deprecated
argument in the GraphQLQuery
derive:
#[macro_use]
extern crate graphql_client;
#[derive(GraphQLQuery)]
#[graphql(
schema_path = "tests/unions/union_schema.graphql",
query_path = "tests/unions/union_query.graphql",
deprecated = "warn"
)]
pub struct MyQuery;
Valid values are:
allow
: the response struct fields are not marked as deprecated.warn
: the response struct fields are marked as#[deprecated]
.deny
: The struct fields are not included in the response struct and using them is a compile error.
The default is warn
.
You can write multiple operations in one query document (one .graphql
file). You can then select one by naming the struct you #[derive(GraphQLQuery)]
on with the same name as one of the operations. This is neat, as it allows sharing fragments between operations.
If you want to name the struct different from query name, you can use selected_operation
argument like this.
#[derive(GraphQLQuery)] #[graphql( schema_path = "tests/unions/union_schema.graphql", query_path = "tests/unions/union_query.graphql", selected_operation = "SearchQuery" )] pub struct MyQuery;
There is an example in the tests.
You can use cargo doc --document-private-items
to generate rustdoc documentation on the generated code.
There is an include
option you can add to your Cargo.toml
. It currently has issues however (see this issue).
See the examples directory in this repository.
Warmest thanks to all those who contributed in any way (not only code) to this project:
- Alex Vlasov (@indifferentalex)
- Ben Boeckel (@mathstuf)
- Chris Fung (@aergonaut)
- Christian Legnitto (@LegNeato)
- Dirkjan Ochtman (@djc)
- Fausto Nunez Alberro (@brainlessdeveloper)
- Hirokazu Hata (@h-michael)
- Peter Gundel (@peterfication)
- Sonny Scroggin (@scrogson)
- Sooraj Chandran (@SoorajChandran)
- Tom Houlé (@tomhoule)
Anyone who interacts with this project in any space, including but not limited to this GitHub repository, must follow our code of conduct.
Licensed under either of these:
- Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)
Unless you explicitly state otherwise, any contribution you intentionally submit for inclusion in the work, as defined in the Apache-2.0 license, shall be dual-licensed as above, without any additional terms or conditions.