Struct LenientForm

pub struct LenientForm<T>(pub T);

A data guard for parsing FromForm types leniently.

This type implements the FromData trait, and like Form, provides a generic means to parse arbitrary structures from incoming form data. Unlike Form, this type uses a lenient parsing strategy: forms that contains a superset of the expected fields (i.e, extra fields) will parse successfully.

Leniency

A LenientForm<T> will parse successfully from an incoming form if the form contains a superset of the fields in T. Said another way, a LenientForm<T> automatically discards extra fields without error. For instance, if an incoming form contains the fields “a”, “b”, and “c” while T only contains “a” and “c”, the form will parse as LenientForm<T>.

Usage

The usage of a LenientForm type is equivalent to that of Form, so we defer details to its documentation.

LenientForm implements FromData, so it can be used directly as a target of the data = "<param>" route parameter. For instance, if some structure of type T implements the FromForm trait, an incoming form can be automatically parsed into the T structure with the following route and handler:

use rocket::request::LenientForm;

#[derive(FromForm)]
struct UserInput {
    value: String
}

#[post("/submit", data = "<user_input>")]
fn submit_task(user_input: LenientForm<UserInput>) -> String {
    format!("Your value: {}", user_input.value)
}

Incoming Data Limits

A LenientForm obeys the same data limits as a Form and defaults to 32KiB. The limit can be increased by setting the limits.forms configuration parameter. For instance, to increase the forms limit to 512KiB for all environments, you may add the following to your Rocket.toml:

[global.limits]
forms = 524288

Tuple Fields

0: T

Implementations

impl<T> LenientForm<T>

pub fn into_inner(self) -> T

Consumes self and returns the parsed value.

Example

use rocket::request::LenientForm;

#[derive(FromForm)]
struct MyForm {
    field: String,
}

#[post("/submit", data = "<form>")]
fn submit(form: LenientForm<MyForm>) -> String {
    form.into_inner().field
}

Trait Implementations

impl<T: Debug> Debug for LenientForm<T>

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

Formats the value using the given formatter.

impl<T> Deref for LenientForm<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<'f, T: FromForm<'f>> FromData<'f> for LenientForm<T>

type Error = FormDataError<'f, <T as FromForm<'f>>::Error>

The associated error to be returned when the guard fails.

type Owned = String

The owned type returned from FromData::transform().

type Borrowed = str

The borrowed type consumed by FromData::from_data() when FromData::transform() returns a Transform::Borrowed.

fn transform( r: &Request<'_>, d: Data, ) -> Transform<Outcome<Self::Owned, Self::Error>>

Transforms data into a value of type Self::Owned.

fn from_data( _: &Request<'_>, o: Transformed<'f, Self>, ) -> Outcome<Self, Self::Error>

Validates, parses, and converts the incoming request body data into an instance of Self.

impl<'q, T: FromForm<'q>> FromQuery<'q> for LenientForm<T>

type Error = <T as FromForm<'q>>::Error

The associated error to be returned if parsing/validation fails.

fn from_query(q: Query<'q>) -> Result<Self, Self::Error>

Parses and validates an instance of Self from a query or returns an Error if parsing or validation fails.

impl<'f, A, T: FromUriParam<Query, A> + FromForm<'f>> FromUriParam<Query, A> for LenientForm<T>

type Target = <T as FromUriParam<Query, A>>::Target

The resulting type of this conversion.

fn from_uri_param(param: A) -> 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.