Struct validators::Result

source · 
pub struct Result<T, E, D = ()>(_, _);
Expand description

A wrapper of std::result::Result, in order to implement the FromFormField trait of Rocket and the Deserialize trait of serde.

This struct uses the FromParam trait to implement the FromFormField trait (only impl the from_value method) so that it can remain the error type for checking later. This struct implements the Deserialize trait so that it can remain the error type for checking later.

Implementations

Methods from Deref<Target = Result<T, E>>

Returns true if the result is Ok.

Examples

Basic usage:

let x: Result<i32, &str> = Ok(-3);
assert_eq!(x.is_ok(), true);

let x: Result<i32, &str> = Err("Some error message");
assert_eq!(x.is_ok(), false);

Returns true if the result is Err.

Examples

Basic usage:

let x: Result<i32, &str> = Ok(-3);
assert_eq!(x.is_err(), false);

let x: Result<i32, &str> = Err("Some error message");
assert_eq!(x.is_err(), true);

Converts from &Result<T, E> to Result<&T, &E>.

Produces a new Result, containing a reference into the original, leaving the original in place.

Examples

Basic usage:

let x: Result<u32, &str> = Ok(2);
assert_eq!(x.as_ref(), Ok(&2));

let x: Result<u32, &str> = Err("Error");
assert_eq!(x.as_ref(), Err(&"Error"));

Converts from &mut Result<T, E> to Result<&mut T, &mut E>.

Examples

Basic usage:

fn mutate(r: &mut Result<i32, i32>) {
    match r.as_mut() {
        Ok(v) => *v = 42,
        Err(e) => *e = 0,
    }
}

let mut x: Result<i32, i32> = Ok(2);
mutate(&mut x);
assert_eq!(x.unwrap(), 42);

let mut x: Result<i32, i32> = Err(13);
mutate(&mut x);
assert_eq!(x.unwrap_err(), 0);

Converts from Result<T, E> (or &Result<T, E>) to Result<&<T as Deref>::Target, &E>.

Coerces the Ok variant of the original Result via Deref and returns the new Result.

Examples
let x: Result<String, u32> = Ok("hello".to_string());
let y: Result<&str, &u32> = Ok("hello");
assert_eq!(x.as_deref(), y);

let x: Result<String, u32> = Err(42);
let y: Result<&str, &u32> = Err(&42);
assert_eq!(x.as_deref(), y);

Converts from Result<T, E> (or &mut Result<T, E>) to Result<&mut <T as DerefMut>::Target, &mut E>.

Coerces the Ok variant of the original Result via DerefMut and returns the new Result.

Examples
let mut s = "HELLO".to_string();
let mut x: Result<String, u32> = Ok("hello".to_string());
let y: Result<&mut str, &mut u32> = Ok(&mut s);
assert_eq!(x.as_deref_mut().map(|x| { x.make_ascii_uppercase(); x }), y);

let mut i = 42;
let mut x: Result<String, u32> = Err(42);
let y: Result<&mut str, &mut u32> = Err(&mut i);
assert_eq!(x.as_deref_mut().map(|x| { x.make_ascii_uppercase(); x }), y);

Returns an iterator over the possibly contained value.

The iterator yields one value if the result is Result::Ok, otherwise none.

Examples

Basic usage:

let x: Result<u32, &str> = Ok(7);
assert_eq!(x.iter().next(), Some(&7));

let x: Result<u32, &str> = Err("nothing!");
assert_eq!(x.iter().next(), None);

Returns a mutable iterator over the possibly contained value.

The iterator yields one value if the result is Result::Ok, otherwise none.

Examples

Basic usage:

let mut x: Result<u32, &str> = Ok(7);
match x.iter_mut().next() {
    Some(v) => *v = 40,
    None => {},
}
assert_eq!(x, Ok(40));

let mut x: Result<u32, &str> = Err("nothing!");
assert_eq!(x.iter_mut().next(), None);
🔬This is a nightly-only experimental API. (option_result_contains)

Returns true if the result is an Ok value containing the given value.

Examples
#![feature(option_result_contains)]

let x: Result<u32, &str> = Ok(2);
assert_eq!(x.contains(&2), true);

let x: Result<u32, &str> = Ok(3);
assert_eq!(x.contains(&2), false);

let x: Result<u32, &str> = Err("Some error message");
assert_eq!(x.contains(&2), false);
🔬This is a nightly-only experimental API. (result_contains_err)

Returns true if the result is an Err value containing the given value.

Examples
#![feature(result_contains_err)]

let x: Result<u32, &str> = Ok(2);
assert_eq!(x.contains_err(&"Some error message"), false);

let x: Result<u32, &str> = Err("Some error message");
assert_eq!(x.contains_err(&"Some error message"), true);

let x: Result<u32, &str> = Err("Some other error message");
assert_eq!(x.contains_err(&"Some error message"), false);

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.
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Deserialize this value from the given Serde deserializer. Read more
Converts to this type from the input type.
Converts to this type from the input type.
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
Feeds this value into the given Hasher. Read more
Feeds a slice of this type into the given Hasher. Read more
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 !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
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

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.

Returns the argument unchanged.

The form guard’s parsing context.
Initializes and returns the parsing context for Self.
Processes the value field field.
Processes the data field field.
Finalizes parsing. Returns the parsed value when successful or collection of Errors otherwise. Read more
Processes the external form or field error _error. Read more
Returns a default value, if any, to use when a value is desired and parsing fails. Read more
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
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