Struct rocket::request::LenientForm

pub struct LenientForm<'f, T: FromForm<'f> + 'f>(_);

A FromData type 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. We provide shallow information here.

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:

#[post("/form_submit", data = "<param>")]
fn submit(form: LenientForm<T>) ... { ... }

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

Methods

impl<'f, T: FromForm<'f> + 'f> LenientForm<'f, T>

fn get(&'f self) -> &T

Immutably borrow the parsed type.

Example

use rocket::request::LenientForm;

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

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

fn raw_form_string(&'f self) -> &str

Returns the raw form string that was used to parse the encapsulated object.

Example

use rocket::request::LenientForm;

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

#[post("/submit", data = "<form>")]
fn submit(form: LenientForm<MyForm>) -> String {
    format!("Raw form string is: {}", form.raw_form_string())
}

impl<'f, T: FromForm<'f> + 'static> LenientForm<'f, T>

fn into_inner(self) -> T

Consumes self and returns the parsed value. For safety reasons, this method may only be called when the parsed value contains no non-'static references.

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<'f, T: FromForm<'f> + Debug + 'f> Debug for LenientForm<'f, T>

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

Formats the value using the given formatter.

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

type Error = Option<String>

The raw form string, if it was able to be retrieved from the request.

fn from_data(request: &Request, data: Data) -> Outcome<Self, Self::Error>

Parses a LenientForm from incoming form data.

If the content type of the request data is not application/x-www-form-urlencoded, Forwards the request. If the form data cannot be parsed into a T, a Failure with status code UnprocessableEntity is returned. If the form string is malformed, a Failure with status code BadRequest is returned. Finally, if reading the incoming stream fails, returns a Failure with status code InternalServerError. In all failure cases, the raw form string is returned if it was able to be retrieved from the incoming stream.

All relevant warnings and errors are written to the console in Rocket logging format.