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#[repr(transparent)]
pub struct Json<T>(pub T);
Available on crate feature json only.
Expand description

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

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

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

The resulting type after dereferencing.

Dereferences the value.

Mutably dereferences the value.

Converts to this type from the input type.

The associated error to be returned when the guard fails.

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

Parse a value of T from a form value field. Read more

Parse a value of T from a form data field. Read more

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

The resulting type of this conversion.

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. Read more

The resulting type of this conversion.

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. Read more

The resulting type of this conversion.

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. Read more

The resulting type of this conversion.

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. Read more

The resulting type of this conversion.

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. Read more

The resulting type of this conversion.

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. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

The length of the value.

Convert len into u64.

The zero value for L.

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

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

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

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.

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

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

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Compare self to key and return true if they are equal.

Converts to this type from the input type.

Returns the argument unchanged.

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

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

Converts self into a collection.

Should always be Self

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

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

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