Define a GraphQL object with methods
*[See also the Book](https://async-graphql.github.io/async-graphql/en/define_complex_object.html).*
All methods are converted to camelCase.
# Macro attributes
| name | Object name | string | Y |
| rename_fields | Rename all the fields according to the given case convention. The possible values are "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE".| string | Y |
| rename_args | Rename all the arguments according to the given case convention. The possible values are "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE".| string | Y |
| cache_control | Object cache control | [`CacheControl`](struct.CacheControl.html) | Y |
| extends | Add fields to an entity that's defined in another service | bool | Y |
| use_type_description | Specifies that the description of the type is on the type declaration. [`Description`]()(derive.Description.html) | bool | Y |
| visible | If `false`, it will not be displayed in introspection. *[See also the Book](https://async-graphql.github.io/async-graphql/en/visibility.html).* | bool | Y |
| visible | Call the specified function. If the return value is `false`, it will not be displayed in introspection. | string | Y |
| serial | Resolve each field sequentially. | bool | Y |
# Field attributes
| skip | Skip this field | bool | Y |
| name | Field name | string | Y |
| desc | Field description | string | Y |
| deprecation | Field deprecated | bool | Y |
| deprecation | Field deprecation reason | string | Y |
| cache_control | Field cache control | [`CacheControl`](struct.CacheControl.html) | Y |
| external | Mark a field as owned by another service. This allows service A to use fields from service B while also knowing at runtime the types of that field. | bool | Y |
| provides | Annotate the expected returned fieldset from a field on a base type that is guaranteed to be selectable by the gateway. | string | Y |
| requires | Annotate the required input fieldset from a base type for a resolver. It is used to develop a query plan where the required fields may not be needed by the client, but the service may need additional information from other services. | string | Y |
| guard | Field of guard *[See also the Book](https://async-graphql.github.io/async-graphql/en/field_guard.html)* | string | Y |
| visible | If `false`, it will not be displayed in introspection. *[See also the Book](https://async-graphql.github.io/async-graphql/en/visibility.html).* | bool | Y |
| visible | Call the specified function. If the return value is `false`, it will not be displayed in introspection. | string | Y |
| complexity | Custom field complexity. *[See also the Book](https://async-graphql.github.io/async-graphql/en/depth_and_complexity.html).* | bool | Y |
| complexity | Custom field complexity. | string | Y |
| derived | Generate derived fields *[See also the Book](https://async-graphql.github.io/async-graphql/en/derived_fields.html).* | object | Y |
# Field argument attributes
| name | Argument name | string | Y |
| desc | Argument description | string | Y |
| default | Use `Default::default` for default value | none | Y |
| default | Argument default value | literal | Y |
| default_with | Expression to generate default value | code string | Y |
| validator | Input value validator *[See also the Book](https://async-graphql.github.io/async-graphql/en/input_value_validators.html)* | object | Y |
| visible | If `false`, it will not be displayed in introspection. *[See also the Book](https://async-graphql.github.io/async-graphql/en/visibility.html).* | bool | Y |
| visible | Call the specified function. If the return value is `false`, it will not be displayed in introspection. | string | Y |
| secret | Mark this field as a secret, it will not output the actual value in the log. | bool | Y |
| key | Is entity key(for Federation) | bool | Y |
# Derived argument attributes
| name | Generated derived field name | string | N |
| into | Type to derived an into | string | Y |
| with | Function to apply to manage advanced use cases | string| Y |
# Valid field return types
- Scalar values, such as `i32` and `bool`. `usize`, `isize`, `u128` and `i128` are not
supported
- `Vec<T>`, such as `Vec<i32>`
- Slices, such as `&[i32]`
- `Option<T>`, such as `Option<i32>`
- `BTree<T>`, `HashMap<T>`, `HashSet<T>`, `BTreeSet<T>`, `LinkedList<T>`, `VecDeque<T>`
- GraphQL objects.
- GraphQL enums.
- References to any of the above types, such as `&i32` or `&Option<String>`.
- `Result<T, E>`, such as `Result<i32, E>`
# Context
You can define a context as an argument to a method, and the context should be the first argument to the method.
```ignore
#[Object]
impl Query {
async fn value(&self, ctx: &Context<'_>) -> { ... }
}
```
# Examples
Implements GraphQL Object for struct.
```rust
use async_graphql::*;
struct Query {
value: i32,
}
#[Object]
impl Query {
/// value
async fn value(&self) -> i32 {
self.value
}
/// reference value
async fn value_ref(&self) -> &i32 {
&self.value
}
/// value with error
async fn value_with_error(&self) -> Result<i32> {
Ok(self.value)
}
async fn value_with_arg(&self, #[graphql(default = 1)] a: i32) -> i32 {
a
}
}
# tokio::runtime::Runtime::new().unwrap().block_on(async move {
let schema = Schema::new(Query { value: 10 }, EmptyMutation, EmptySubscription);
let res = schema.execute(r#"{
value
valueRef
valueWithError
valueWithArg1: valueWithArg
valueWithArg2: valueWithArg(a: 99)
}"#).await.into_result().unwrap().data;
assert_eq!(res, value!({
"value": 10,
"valueRef": 10,
"valueWithError": 10,
"valueWithArg1": 1,
"valueWithArg2": 99
}));
# });
```
# Examples
Implements GraphQL Object for trait object.
```rust
use async_graphql::*;
trait MyTrait: Send + Sync {
fn name(&self) -> &str;
}
#[Object]
impl dyn MyTrait {
#[graphql(name = "name")]
async fn gql_name(&self) -> &str {
self.name()
}
}
struct MyObj(String);
impl MyTrait for MyObj {
fn name(&self) -> &str {
&self.0
}
}
struct Query;
#[Object]
impl Query {
async fn objs(&self) -> Vec<Box<dyn MyTrait>> {
vec![
Box::new(MyObj("a".to_string())),
Box::new(MyObj("b".to_string())),
]
}
}
# tokio::runtime::Runtime::new().unwrap().block_on(async move {
let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
let res = schema.execute("{ objs { name } }").await.into_result().unwrap().data;
assert_eq!(res, value!({
"objs": [
{ "name": "a" },
{ "name": "b" },
]
}));
# });
```