Struct Json

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

Available on crate feature json only.

The JSON guard: easily consume and return JSON.

Sending JSON

To respond with serialized JSON data, return a Json<T> type, where T implements Serialize from serde. The content type of the response is set to application/json automatically.

use rocket::serde::json::Json;

#[get("/users/<id>")]
fn user(id: usize) -> Json<User> {
    let user_from_id = User::from(id);
    /* ... */
    Json(user_from_id)
}

Receiving JSON

Json is both a data guard and a form guard.

Data Guard

To deserialize request body data as JSON , add a data route argument with a target type of Json<T>, where T is some type you’d like to parse from JSON. T must implement serde::Deserialize.

use rocket::serde::json::Json;

#[post("/user", format = "json", data = "<user>")]
fn new_user(user: Json<User>) {
    /* ... */
}

You don’t need to use format = "json", but it may be what you want. Using format = json means that any request that doesn’t specify “application/json” as its Content-Type header value will not be routed to the handler.

Form Guard

Json<T>, as a form guard, accepts value and data fields and parses the data as a T. Simple use Json<T>:

use rocket::form::{Form, FromForm};
use rocket::serde::json::Json;

#[derive(FromForm)]
struct User<'r> {
    name: &'r str,
    metadata: Json<Metadata>
}

#[post("/user", data = "<form>")]
fn new_user(form: Form<User<'_>>) {
    /* ... */
}

Incoming Data Limits

The default size limit for incoming JSON data is 1MiB. Setting a limit protects your application from denial of service (DoS) attacks and from resource exhaustion through high memory consumption. The limit can be increased by setting the limits.json configuration parameter. For instance, to increase the JSON limit to 5MiB for all environments, you may add the following to your Rocket.toml:

[global.limits]
json = 5242880

Tuple Fields

0: T

Implementations

impl<T> Json<T>

pub fn into_inner(self) -> T

Consumes the JSON wrapper and returns the wrapped item.

Example

let string = "Hello".to_string();
let my_json = Json(string);
assert_eq!(my_json.into_inner(), "Hello".to_string());

Trait Implementations

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

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

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

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

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

Formats the value using the given formatter.

impl<T> Deref for Json<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T> DerefMut for Json<T>

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

Mutably dereferences the value.

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

fn from(value: T) -> Self

Converts to this type from the input type.

impl<'r, T: Deserialize<'r>> FromData<'r> for Json<T>

type Error = Error<'r>

The associated error to be returned when the guard fails.

fn from_data<'life0, 'async_trait>( req: &'r Request<'life0>, data: Data<'r>, ) -> Pin<Box<dyn Future<Output = Outcome<'r, Self>> + Send + 'async_trait>>

where Self: 'async_trait, 'r: 'async_trait, 'life0: 'async_trait,

Asynchronously validates, parses, and converts an instance of Self from the incoming request body data.

impl<'v, T: Deserialize<'v> + Send> FromFormField<'v> for Json<T>

fn from_value(field: ValueField<'v>) -> Result<Self, Errors<'v>>

Parse a value of T from a form value field.

fn from_data<'life0, 'async_trait>( f: DataField<'v, 'life0>, ) -> Pin<Box<dyn Future<Output = Result<Self, Errors<'v>>> + Send + 'async_trait>>

where Self: 'async_trait, 'v: 'async_trait, 'life0: 'async_trait,

Parse a value of T from a form data field.

fn default() -> Option<Self>

Returns a default value, if any exists, to be used during lenient parsing when the form field is missing.

impl<'x, T: Serialize> FromUriParam<Query, &'x Json<T>> for Json<T>

type Target = &'x Json<T>

The resulting type of this conversion.

fn from_uri_param(param: &'x Json<T>) -> &'x Json<T>

Converts a value of type T into a value of type Self::Target. The resulting value of type Self::Target will be rendered into a URI using its UriDisplay implementation.

impl<'a, T: Serialize> FromUriParam<Query, &'a T> for Json<T>

type Target = Json<&'a T>

The resulting type of this conversion.

fn from_uri_param(param: &'a T) -> Self::Target

Converts a value of type T into a value of type Self::Target. The resulting value of type Self::Target will be rendered into a URI using its UriDisplay implementation.

impl<'x, T: Serialize> FromUriParam<Query, &'x mut Json<T>> for Json<T>

type Target = &'x mut Json<T>

The resulting type of this conversion.

fn from_uri_param(param: &'x mut Json<T>) -> &'x mut Json<T>

Converts a value of type T into a value of type Self::Target. The resulting value of type Self::Target will be rendered into a URI using its UriDisplay implementation.

impl<'a, T: Serialize> FromUriParam<Query, &'a mut T> for Json<T>

type Target = Json<&'a mut T>

The resulting type of this conversion.

fn from_uri_param(param: &'a mut T) -> Self::Target

Converts a value of type T into a value of type Self::Target. The resulting value of type Self::Target will be rendered into a URI using its UriDisplay implementation.

impl<T: Serialize> FromUriParam<Query, Json<T>> for Json<T>

type Target = Json<T>

The resulting type of this conversion.

fn from_uri_param(param: Json<T>) -> Json<T>

Converts a value of type T into a value of type Self::Target. The resulting value of type Self::Target will be rendered into a URI using its UriDisplay implementation.

impl<T: Serialize> FromUriParam<Query, T> for Json<T>

type Target = Json<T>

The resulting type of this conversion.

fn from_uri_param(param: T) -> Self::Target

Converts a value of type T into a value of type Self::Target. The resulting value of type Self::Target will be rendered into a URI using its UriDisplay implementation.

impl<T: Hash> Hash for Json<T>

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<L, T: Len<L>> Len<L> for Json<T>

fn len(&self) -> L

The length of the value.

fn len_into_u64(len: L) -> u64

Convert len into u64.

fn zero_len() -> L

The zero value for L.

impl<T: Ord> Ord for Json<T>

fn cmp(&self, other: &Json<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T: PartialEq> PartialEq for Json<T>

fn eq(&self, other: &Json<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: PartialOrd> PartialOrd for Json<T>

fn partial_cmp(&self, other: &Json<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'r, T: Serialize> Responder<'r, 'static> for Json<T>

Serializes the wrapped value into JSON. Returns a response with Content-Type JSON and a fixed-size body with the serialized value. If serialization fails, an Err of Status::InternalServerError is returned.

fn respond_to(self, req: &'r Request<'_>) -> Result<'static>

Returns Ok if a Response could be generated successfully. Otherwise, returns an Err with a failing Status.

impl<T: Serialize> UriDisplay<Query> for Json<T>

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

Formats self in a URI-safe manner using the given formatter.

impl<T: Eq> Eq for Json<T>

impl<T> StructuralPartialEq for Json<T>