[][src]Trait rocket_http::uri::FromUriParam

pub trait FromUriParam<P: UriPart, T> {
    type Target: UriDisplay<P>;
    fn from_uri_param(param: T) -> Self::Target;
}

Conversion trait for parameters used in uri! invocations.

Overview

In addition to implementing UriDisplay, to use a custom type in a uri! expression, the FromUriParam trait must be implemented. The UriDisplay derive automatically generates identity implementations of FromUriParam, so in the majority of cases, as with UriDisplay, this trait is never implemented manually.

In the rare case that UriDisplay is implemented manually, this trait, too, must be implemented explicitly. In the majority of cases, implementation can be automated. Rocket provides the impl_from_uri_param_identity macro to generate the identity implementations automatically. For a type T, these are:

  • impl<P: UriPart> FromUriParam<P, T> for T
  • impl<'x, P: UriPart> FromUriParam<P, &'x T> for T
  • impl<'x, P: UriPart> FromUriParam<P, &'x mut T> for T

See impl_from_uri_param_identity for usage details.

Code Generation

This trait is invoked once per expression passed into a uri! invocation. In particular, for a route URI parameter of type T and a user-supplied expression of type S, <T as FromUriParam<S>>::from_uri_param is invoked. The returned value is used in place of the user's value and rendered using its UriDisplay implementation.

This trait allows types that differ from the route URI parameter's types to be used in their place at no cost. For instance, the following implementation, provided by Rocket, allows an &str to be used in a uri! invocation for route URI parameters declared as String:

impl<'a, P: UriPart> FromUriParam<P, &'a str> for String {
    type Target = &'a str;
}

Because the FromUriParam::Target type is the same as the input type, the conversion is a no-op and free of cost, allowing an &str to be used in place of a String without penalty. A similar no-op conversion exists for &RawStr:

impl<'a, 'b, P: UriPart> FromUriParam<P, &'a str> for &'b RawStr {
    type Target = &'a str;
}

Provided Implementations

The following types have identity implementations:

  • String, i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128, usize, f32, f64, bool, IpAddr, Ipv4Addr, Ipv6Addr, &str, &RawStr, Cow<str>

The following conversions are implemented:

  • &str to String
  • &str to RawStr
  • String to &str
  • String to RawStr

The following types have identity implementations only in Path:

  • &Path, PathBuf

The following conversions are implemented only in Path:

  • &str to &Path
  • &str to PathBuf
  • PathBuf to &Path

See Foreign Impls for all provided implementations.

Implementing

This trait should only be implemented when you'd like to allow a type different from the route's declared type to be used in its place in a uri! invocation. For instance, if the route has a type of T and you'd like to use a type of S in a uri! invocation, you'd implement FromUriParam<P, T> for S where P is Path for conversions valid in the path part of a URI, Uri for conversions valid in the query part of a URI, or P: UriPart when a conversion is valid in either case.

This is typically only warranted for owned-value types with corresponding reference types: String and &str, for instance. In this case, it's desirable to allow an &str to be used in place of a String.

When implementing FromUriParam, be aware that Rocket will use the UriDisplay implementation of FromUriParam::Target, not of the source type. Incorrect implementations can result in creating unsafe URIs.

Example

The following example implements FromUriParam<Query, (&str, &str)> for a User type. The implementation allows an (&str, &str) type to be used in a uri! invocation where a User type is expected in the query part of the URI.

use std::fmt;

use rocket::http::RawStr;
use rocket::http::uri::{Formatter, UriDisplay, FromUriParam, Query};

#[derive(FromForm)]
struct User<'a> {
    name: &'a RawStr,
    nickname: String,
}

impl<'a> UriDisplay<Query> for User<'a> {
    fn fmt(&self, f: &mut Formatter<Query>) -> fmt::Result {
        f.write_named_value("name", &self.name)?;
        f.write_named_value("nickname", &self.nickname)
    }
}

impl<'a, 'b> FromUriParam<Query, (&'a str, &'b str)> for User<'a> {
    type Target = User<'a>;

    fn from_uri_param((name, nickname): (&'a str, &'b str)) -> User<'a> {
        User { name: name.into(), nickname: nickname.to_string() }
    }
}

With these implementations, the following typechecks:

use rocket::http::RawStr;
use rocket::request::Form;

#[post("/<name>?<user..>")]
fn some_route(name: &RawStr, user: Form<User>)  { /* .. */ }

let uri = uri!(some_route: name = "hey", user = ("Robert Mike", "Bob"));
assert_eq!(uri.path(), "/hey");
assert_eq!(uri.query(), Some("name=Robert%20Mike&nickname=Bob"));

Associated Types

The resulting type of this conversion.

Required Methods

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.

Implementations on Foreign Types

impl<P: UriPart> FromUriParam<P, String> for String
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impl<'x, P: UriPart> FromUriParam<P, &'x String> for String
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impl<'x, P: UriPart> FromUriParam<P, &'x mut String> for String
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impl<P: UriPart> FromUriParam<P, i8> for i8
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impl<'x, P: UriPart> FromUriParam<P, &'x i8> for i8
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impl<'x, P: UriPart> FromUriParam<P, &'x mut i8> for i8
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impl<P: UriPart> FromUriParam<P, i16> for i16
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impl<'x, P: UriPart> FromUriParam<P, &'x i16> for i16
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impl<'x, P: UriPart> FromUriParam<P, &'x mut i16> for i16
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impl<P: UriPart> FromUriParam<P, i32> for i32
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impl<'x, P: UriPart> FromUriParam<P, &'x i32> for i32
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impl<'x, P: UriPart> FromUriParam<P, &'x mut i32> for i32
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impl<P: UriPart> FromUriParam<P, i64> for i64
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impl<'x, P: UriPart> FromUriParam<P, &'x i64> for i64
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impl<'x, P: UriPart> FromUriParam<P, &'x mut i64> for i64
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impl<P: UriPart> FromUriParam<P, i128> for i128
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impl<'x, P: UriPart> FromUriParam<P, &'x i128> for i128
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impl<'x, P: UriPart> FromUriParam<P, &'x mut i128> for i128
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impl<P: UriPart> FromUriParam<P, isize> for isize
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impl<'x, P: UriPart> FromUriParam<P, &'x isize> for isize
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impl<'x, P: UriPart> FromUriParam<P, &'x mut isize> for isize
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impl<P: UriPart> FromUriParam<P, u8> for u8
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impl<'x, P: UriPart> FromUriParam<P, &'x u8> for u8
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impl<'x, P: UriPart> FromUriParam<P, &'x mut u8> for u8
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impl<P: UriPart> FromUriParam<P, u16> for u16
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impl<'x, P: UriPart> FromUriParam<P, &'x u16> for u16
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impl<'x, P: UriPart> FromUriParam<P, &'x mut u16> for u16
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impl<P: UriPart> FromUriParam<P, u32> for u32
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impl<'x, P: UriPart> FromUriParam<P, &'x u32> for u32
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impl<'x, P: UriPart> FromUriParam<P, &'x mut u32> for u32
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impl<P: UriPart> FromUriParam<P, u64> for u64
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impl<'x, P: UriPart> FromUriParam<P, &'x u64> for u64
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impl<'x, P: UriPart> FromUriParam<P, &'x mut u64> for u64
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impl<P: UriPart> FromUriParam<P, u128> for u128
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impl<'x, P: UriPart> FromUriParam<P, &'x u128> for u128
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impl<'x, P: UriPart> FromUriParam<P, &'x mut u128> for u128
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impl<P: UriPart> FromUriParam<P, usize> for usize
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impl<'x, P: UriPart> FromUriParam<P, &'x usize> for usize
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impl<'x, P: UriPart> FromUriParam<P, &'x mut usize> for usize
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impl<P: UriPart> FromUriParam<P, f32> for f32
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impl<'x, P: UriPart> FromUriParam<P, &'x f32> for f32
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impl<'x, P: UriPart> FromUriParam<P, &'x mut f32> for f32
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impl<P: UriPart> FromUriParam<P, f64> for f64
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impl<'x, P: UriPart> FromUriParam<P, &'x f64> for f64
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impl<'x, P: UriPart> FromUriParam<P, &'x mut f64> for f64
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impl<P: UriPart> FromUriParam<P, bool> for bool
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impl<'x, P: UriPart> FromUriParam<P, &'x bool> for bool
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impl<'x, P: UriPart> FromUriParam<P, &'x mut bool> for bool
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impl<P: UriPart> FromUriParam<P, IpAddr> for IpAddr
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impl<'x, P: UriPart> FromUriParam<P, &'x IpAddr> for IpAddr
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impl<'x, P: UriPart> FromUriParam<P, &'x mut IpAddr> for IpAddr
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impl<P: UriPart> FromUriParam<P, Ipv4Addr> for Ipv4Addr
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impl<'x, P: UriPart> FromUriParam<P, &'x Ipv4Addr> for Ipv4Addr
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impl<'x, P: UriPart> FromUriParam<P, &'x mut Ipv4Addr> for Ipv4Addr
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impl<P: UriPart> FromUriParam<P, Ipv6Addr> for Ipv6Addr
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impl<'x, P: UriPart> FromUriParam<P, &'x Ipv6Addr> for Ipv6Addr
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impl<'x, P: UriPart> FromUriParam<P, &'x mut Ipv6Addr> for Ipv6Addr
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impl<'a, P: UriPart> FromUriParam<P, &'a str> for &'a str
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x &'a str> for &'a str
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x mut &'a str> for &'a str
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impl<'a, P: UriPart> FromUriParam<P, Cow<'a, str>> for Cow<'a, str>
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x Cow<'a, str>> for Cow<'a, str>
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x mut Cow<'a, str>> for Cow<'a, str>
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impl<'a, P: UriPart> FromUriParam<P, &'a str> for String
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x &'a str> for String
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x mut &'a str> for String
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impl<'a, P: UriPart> FromUriParam<P, String> for &'a str
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x String> for &'a str
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x mut String> for &'a str
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impl<'a> FromUriParam<Path, &'a Path> for &'a Path
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impl<'x, 'a> FromUriParam<Path, &'x &'a Path> for &'a Path
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impl<'x, 'a> FromUriParam<Path, &'x mut &'a Path> for &'a Path
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impl FromUriParam<Path, PathBuf> for PathBuf
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impl<'x> FromUriParam<Path, &'x PathBuf> for PathBuf
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impl<'x> FromUriParam<Path, &'x mut PathBuf> for PathBuf
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impl<'a> FromUriParam<Path, &'a Path> for PathBuf
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impl<'x, 'a> FromUriParam<Path, &'x &'a Path> for PathBuf
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impl<'x, 'a> FromUriParam<Path, &'x mut &'a Path> for PathBuf
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impl<'a> FromUriParam<Path, PathBuf> for &'a Path
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impl<'x, 'a> FromUriParam<Path, &'x PathBuf> for &'a Path
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impl<'x, 'a> FromUriParam<Path, &'x mut PathBuf> for &'a Path
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impl<'a> FromUriParam<Path, &'a str> for PathBuf
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A no cost conversion allowing an &str to be used in place of a PathBuf.

impl<'a, 'b> FromUriParam<Path, &'a &'b str> for PathBuf
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A no cost conversion allowing an &&str to be used in place of a PathBuf.

impl<P: UriPart, A, T: FromUriParam<P, A>> FromUriParam<P, A> for Option<T>
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A no cost conversion allowing any T to be used in place of an Option<T>.

impl<P: UriPart, A, E, T: FromUriParam<P, A>> FromUriParam<P, A> for Result<T, E>
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A no cost conversion allowing T to be used in place of an Result<T, E>.

Implementors

impl<'a, 'b, P: UriPart> FromUriParam<P, &'a str> for &'b RawStr
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impl<'a, P: UriPart> FromUriParam<P, &'a RawStr> for &'a RawStr
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impl<'a, P: UriPart> FromUriParam<P, String> for &'a RawStr
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impl<'x, 'a, 'b, P: UriPart> FromUriParam<P, &'x &'a str> for &'b RawStr
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impl<'x, 'a, 'b, P: UriPart> FromUriParam<P, &'x mut &'a str> for &'b RawStr
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x &'a RawStr> for &'a RawStr
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x String> for &'a RawStr
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x mut &'a RawStr> for &'a RawStr
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impl<'x, 'a, P: UriPart> FromUriParam<P, &'x mut String> for &'a RawStr
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