Struct axum::Json

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pub struct Json<T>(pub T);
Expand description

JSON Extractor / Response.

When used as an extractor, it can deserialize request bodies into some type that implements serde::de::DeserializeOwned. The request will be rejected (and a JsonRejection will be returned) if:

  • The request doesn’t have a Content-Type: application/json (or similar) header.
  • The body doesn’t contain syntactically valid JSON.
  • The body contains syntactically valid JSON, but it couldn’t be deserialized into the target type.
  • Buffering the request body fails.

⚠️ Since parsing JSON requires consuming the request body, the Json extractor must be last if there are multiple extractors in a handler. See “the order of extractors”

See JsonRejection for more details.

§Extractor example

use axum::{
    extract,
    routing::post,
    Router,
};
use serde::Deserialize;

#[derive(Deserialize)]
struct CreateUser {
    email: String,
    password: String,
}

async fn create_user(extract::Json(payload): extract::Json<CreateUser>) {
    // payload is a `CreateUser`
}

let app = Router::new().route("/users", post(create_user));

When used as a response, it can serialize any type that implements serde::Serialize to JSON, and will automatically set Content-Type: application/json header.

§Response example

use axum::{
    extract::Path,
    routing::get,
    Router,
    Json,
};
use serde::Serialize;
use uuid::Uuid;

#[derive(Serialize)]
struct User {
    id: Uuid,
    username: String,
}

async fn get_user(Path(user_id) : Path<Uuid>) -> Json<User> {
    let user = find_user(user_id).await;
    Json(user)
}

async fn find_user(user_id: Uuid) -> User {
    // ...
}

let app = Router::new().route("/users/:id", get(get_user));

Tuple Fields§

§0: T

Implementations§

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impl<T> Json<T>

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pub fn from_bytes(bytes: &[u8]) -> Result<Self, JsonRejection>

Construct a Json<T> from a byte slice. Most users should prefer to use the FromRequest impl but special cases may require first extracting a Request into Bytes then optionally constructing a Json<T>.

Trait Implementations§

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impl<T: Clone> Clone for Json<T>

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fn clone(&self) -> Json<T>

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<T: Debug> Debug for Json<T>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<T: Default> Default for Json<T>

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fn default() -> Json<T>

Returns the “default value” for a type. Read more
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impl<T> Deref for Json<T>

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &Self::Target

Dereferences the value.
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impl<T> DerefMut for Json<T>

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fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.
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impl<T> From<T> for Json<T>

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fn from(inner: T) -> Self

Converts to this type from the input type.
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impl<T, S> FromRequest<S> for Json<T>
where T: DeserializeOwned, S: Send + Sync,

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type Rejection = JsonRejection

If the extractor fails it’ll use this “rejection” type. A rejection is a kind of error that can be converted into a response.
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fn from_request<'life0, 'async_trait>( req: Request, state: &'life0 S, ) -> Pin<Box<dyn Future<Output = Result<Self, Self::Rejection>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait,

Perform the extraction.
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impl<T> IntoResponse for Json<T>
where T: Serialize,

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fn into_response(self) -> Response

Create a response.
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impl<T: Copy> Copy for Json<T>

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impl<T> Freeze for Json<T>
where T: Freeze,

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impl<T> RefUnwindSafe for Json<T>
where T: RefUnwindSafe,

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impl<T> Send for Json<T>
where T: Send,

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impl<T> Sync for Json<T>
where T: Sync,

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impl<T> Unpin for Json<T>
where T: Unpin,

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impl<T> UnwindSafe for Json<T>
where T: UnwindSafe,

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> CloneToUninit for T
where T: Copy,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> From<!> for T

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fn from(t: !) -> T

Converts to this type from the input type.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FromRef<T> for T
where T: Clone,

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fn from_ref(input: &T) -> T

Converts to this type from a reference to the input type.
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impl<H, T> HandlerWithoutStateExt<T> for H
where H: Handler<T, ()>,

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fn into_service(self) -> HandlerService<H, T, ()>

Convert the handler into a Service and no state.
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fn into_make_service(self) -> IntoMakeService<HandlerService<H, T, ()>>

Convert the handler into a MakeService and no state. Read more
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fn into_make_service_with_connect_info<C>( self, ) -> IntoMakeServiceWithConnectInfo<HandlerService<H, T, ()>, C>

Convert the handler into a MakeService which stores information about the incoming connection and has no state. Read more
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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more