2020-04-15 03:15:30 +00:00
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# Apollo Federation集成
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2020-04-22 02:30:21 +00:00
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`Apollo Federation`是一个`GraphQL`网关,它可以组合多个GraphQL服务,允许每服务仅实现它负责的那一部分数据,参考[官方文档](https://www.apollographql.com/docs/apollo-server/federation/introduction)。
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`Async-graphql`可以完全支持`Apollo Federation`的所有功能,但需要对`Schema`定义做一些小小的改造。
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- `async_graphql::Object`和`async_graphql::Interface`的`extends`属性声明这个类别是一个已有类型的扩充。
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- 字段的`external`属性声明这个字段定义来自其它服务。
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- 字段的`provides`属性用于要求网关提供的字段集。
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- 字段的`provides`属性表示解析该字段值需要依赖该类型的字段集。
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2020-06-19 05:03:17 +00:00
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## 实体查找函数
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2020-04-22 02:30:21 +00:00
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```rust
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struct Query;
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2020-09-18 00:52:13 +00:00
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#[Object]
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2020-04-22 02:30:21 +00:00
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impl Query {
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#[entity]
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async fn find_user_by_id(&self, id: ID) -> User {
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2020-06-19 05:03:17 +00:00
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User { ... }
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2020-04-22 02:30:21 +00:00
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}
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2020-06-19 05:03:17 +00:00
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#[entity]
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2020-09-28 09:44:00 +00:00
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async fn find_user_by_id_with_username(&self, #[graphql(key)] id: ID, username: String) -> User {
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2020-06-19 05:03:17 +00:00
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User { ... }
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}
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2020-04-22 02:30:21 +00:00
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2020-06-19 05:03:17 +00:00
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#[entity]
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async fn find_user_by_id_and_username(&self, id: ID, username: String) -> User {
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User { ... }
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}
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2020-04-22 02:30:21 +00:00
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}
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```
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2020-06-19 05:03:17 +00:00
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**注意这三个查找函数的不同,他们都是查找User对象。**
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- find_user_by_id
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使用`id`查找`User`对象,`User`对象的key是`id`。
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- find_user_by_id_with_username
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使用`id`查找`User`对象,`User`对象的key是`id`,并且请求`User`对象的`username`字段值。
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- find_user_by_id_and_username
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使用`id`和`username`查找`User`对象,`User`对象的key是`id`和`username`。
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2020-04-22 02:30:21 +00:00
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2020-04-28 07:41:31 +00:00
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完整的例子请参考https://github.com/async-graphql/examples/tree/master/federation
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