2020-04-15 09:19:26 +00:00
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# 快速开始
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## 添加依赖
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```toml
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[dependencies]
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async-graphql = "1.9.0"
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```
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## 写一个Schema
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一个GraphQL的Schema包含一个必须的查询(Query)根对象，可选的变更(Mutation)根对象和可选的订阅(Subscription)根对象，这些对象类型都是用Rust语言的struct来描述它们，结构的字段对应GraphQL对象的字段，但你需要用`#[field]`来修饰它，这样`Async-graphql`提供的过程宏才能够正确的识别它。
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Async-graphql实现了常用数据类型到GraphQL类型的映射，例如`i32`, `f64`, `Option<T>`, `Vec<T>`等。同时，你也能够[扩展这些基础类型](custom_scalars.md)，基础数据类型在GraphQL里面称为标量。
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下面是一个简单的例子，我们只提供一个查询，返回`a`和`b`的和。
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```rust
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use async_graphql::*;
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struct Query;
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#[Object]
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impl Query {
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#[field(desc = "Returns the sum of a and b")]
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async fn add(a: i32, b: i32) -> i32 {
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a + b
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}
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}
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type MySchema = Schema<Query, EmptyMutation, EmptySubscription>;
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```
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## 执行查询
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