Struct Json

#[must_use]
pub struct Json<T>(pub T);

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:

⚠️ 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));
# let _: Router = app;

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.

If the Serialize implementation decides to fail or if a map with non-string keys is used, a 500 response will be issued whose body is the error message in UTF-8.

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 {
    // ...
    # unimplemented!()
}

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

Fields

0: T

Implementations

impl<T> Json<T> where T: DeserializeOwned,

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

impl<T> Deref for Json<T>

type Target = T;
fn deref(&self) -> &Self::Target

impl<T> DerefMut for Json<T>

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

impl<T> From<T> for Json<T>

fn from(inner: T) -> Self

impl<T> IntoResponse for Json<T> where T: Serialize,

fn into_response(self) -> Response

impl<T, S> FromRequest<S> for Json<T> where T: DeserializeOwned, S: Send + Sync,

type Rejection = JsonRejection;
async fn from_request(req: Request, state: &S) -> Result<Self, Self::Rejection>

impl<T, S> OptionalFromRequest<S> for Json<T> where T: DeserializeOwned, S: Send + Sync,

type Rejection = JsonRejection;
async fn from_request(req: Request, state: &S) -> Result<Option<Self>, Self::Rejection>

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

fn clone(&self) -> Self

impl<T: Copy> Copy for Json<T>

impl<T: Debug> Debug for Json<T>

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

impl<T: Default> Default for Json<T>

fn default() -> Self

Auto Trait Implementations

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

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

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

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

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

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

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

Blanket Implementations

impl<H, T> HandlerWithoutStateExt<T> for Json<T> where H: Handler<T, ()>,

fn into_service(self) -> HandlerService<H, T, ()>
fn into_make_service(self) -> IntoMakeService<HandlerService<H, T, ()>>
fn into_make_service_with_connect_info<C>(self) -> IntoMakeServiceWithConnectInfo<HandlerService<H, T, ()>, C>

impl<P, T> Receiver for Json<T> where P: Deref<Target = T> + ?Sized, T: ?Sized,

type Target = T;

impl<R> Rng for Json<T> where R: RngCore + ?Sized,

impl<R> TryCryptoRng for Json<T> where R: CryptoRng + ?Sized,

impl<R> TryRngCore for Json<T> where R: RngCore + ?Sized,

type Error = never;
fn try_next_u32(&mut self) -> Result<u32, <R as TryRngCore>::Error>
fn try_next_u64(&mut self) -> Result<u64, <R as TryRngCore>::Error>
fn try_fill_bytes(&mut self, dst: &mut [u8]) -> Result<(), <R as TryRngCore>::Error>

impl<ST, DT> CastableFrom<ST, Initialized, Initialized> for Json<T> where ST: ?Sized, DT: ?Sized,

impl<ST, DT> CastableFrom<ST, Uninit, Uninit> for Json<T> where ST: ?Sized, DT: ?Sized,

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

fn type_id(&self) -> TypeId

impl<T> Borrow<T> for Json<T> where T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for Json<T> where T: ?Sized,

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

impl<T> CloneToUninit for Json<T> where T: Clone,

unsafe fn clone_to_uninit(&self, dest: *mut u8)

impl<T> CryptoRng for Json<T> where T: DerefMut, <T as Deref>::Target: CryptoRng,

impl<T> From<T> for Json<T>

fn from(t: T) -> T

Returns the argument unchanged.

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

fn from_ref(input: &T) -> T

impl<T> Instrument for Json<T>

impl<T> Read<Exclusive, BecauseExclusive> for Json<T> where T: ?Sized,

impl<T> RngCore for Json<T> where T: DerefMut, <T as Deref>::Target: RngCore,

fn next_u32(&mut self) -> u32
fn next_u64(&mut self) -> u64
fn fill_bytes(&mut self, dst: &mut [u8])

impl<T> Same for Json<T>

type Output = T;

impl<T> ToOwned for Json<T> where T: Clone,

type Owned = T;
fn to_owned(&self) -> T
fn clone_into(&self, target: &mut T)

impl<T> WithSubscriber for Json<T>

impl<T, U> Into<U> for Json<T> where U: From<T>,

fn into(self) -> U

Calls U::from(self).

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

impl<T, U> TryFrom<U> for Json<T> where U: Into<T>,

type Error = never;
fn try_from(value: U) -> Result<T, never>

impl<T, U> TryInto<U> for Json<T> where U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error;
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

impl<V, T> VZip<V> for Json<T> where V: MultiLane<T>,

fn vzip(self) -> V