2020-04-15 03:15:30 +00:00
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# Interface
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2020-05-09 17:53:41 +00:00
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2020-05-11 04:39:43 +00:00
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`Interface` is used to abstract `Object`s with common fields.
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2020-09-01 05:47:22 +00:00
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`Async-graphql` implements it as a wrapper.
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The wrapper will forward field resolution to the `Object` that implements this `Interface`.
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Therefore, the `Object`'s fields' type and arguments must match with the `Interface`'s.
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2020-05-09 17:53:41 +00:00
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2020-09-01 05:47:22 +00:00
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`Async-graphql` implements auto conversion from `Object` to `Interface`, you only need to call `Into::into`.
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2020-05-09 17:53:41 +00:00
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2020-09-01 05:47:22 +00:00
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Interface field names are transformed to camelCase for the schema definition.
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If you need e.g. a snake_cased GraphQL field name, you can use both the `name` and `method` attributes.
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2020-05-28 15:50:01 +00:00
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2020-09-01 05:47:22 +00:00
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- When `name` and `method` exist together, `name` is the GraphQL field name and the `method` is the resolver function name.
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2020-05-28 16:01:04 +00:00
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- When only `name` exists, `name.to_camel_case()` is the GraphQL field name and the `name` is the resolver function name.
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2020-05-28 15:50:01 +00:00
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2020-05-09 17:53:41 +00:00
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```rust
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use async_graphql::*;
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struct Circle {
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radius: f32,
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}
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2020-09-13 04:12:32 +00:00
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#[GQLObject]
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2020-05-09 17:53:41 +00:00
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impl Circle {
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async fn area(&self) -> f32 {
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std::f32::consts::PI * self.radius * self.radius
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}
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async fn scale(&self, s: f32) -> Shape {
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Circle { radius: self.radius * s }.into()
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}
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2020-05-28 15:50:01 +00:00
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#[field(name = "short_description")]
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async fn short_description(&self) -> String {
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"Circle".to_string()
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}
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2020-05-09 17:53:41 +00:00
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}
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struct Square {
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width: f32,
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}
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2020-09-13 04:12:32 +00:00
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#[GQLObject]
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2020-05-09 17:53:41 +00:00
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impl Square {
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async fn area(&self) -> f32 {
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self.width * self.width
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}
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async fn scale(&self, s: f32) -> Shape {
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Square { width: self.width * s }.into()
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}
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2020-05-28 15:50:01 +00:00
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#[field(name = "short_description")]
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async fn short_description(&self) -> String {
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"Square".to_string()
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}
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2020-05-09 17:53:41 +00:00
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}
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2020-09-13 04:12:32 +00:00
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#[derive(GQLInterface)]
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#[graphql(
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2020-05-09 17:53:41 +00:00
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field(name = "area", type = "f32"),
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field(name = "scale", type = "Shape", arg(name = "s", type = "f32"))
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2020-05-28 15:50:01 +00:00
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field(name = "short_description", method = "short_description", type = "String")
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2020-05-09 17:53:41 +00:00
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)]
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2020-05-11 04:39:43 +00:00
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enum Shape {
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Circle(Circle),
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Square(Square),
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}
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```
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