# Struct hyper::header::HeaderValue [−] [src]

    pub struct HeaderValue { /* fields omitted */ }

Represents an HTTP header field value.

In practice, HTTP header field values are usually valid ASCII. However, the HTTP spec allows for a header value to contain opaque bytes as well. In this case, the header field value is not able to be represented as a string.

To handle this, the `HeaderValue` is useable as a type and can be compared with strings and implements `Debug`. A `to_str` fn is provided that returns an `Err` if the header value contains non visible ascii characters.

## Implementations

### `impl HeaderValue` [src]

#### `pub fn from_static(src: &'static str) -> HeaderValue` [src]

Convert a static string to a `HeaderValue`.

This function will not perform any copying, however the string is checked to ensure that no invalid characters are present. Only visible ASCII characters (32-127) are permitted.

# Panics

This function panics if the argument contains invalid header value characters.

# Examples

    let val = HeaderValue::from_static("hello");
    assert_eq!(val, "hello");

#### `pub fn from_str(src: &str) -> Result<HeaderValue, InvalidHeaderValue>` [src]

Attempt to convert a string to a `HeaderValue`.

If the argument contains invalid header value characters, an error is returned. Only visible ASCII characters (32-127) are permitted. Use `from_bytes` to create a `HeaderValue` that includes opaque octets (128-255).

This function is intended to be replaced in the future by a `TryFrom` implementation once the trait is stabilized in std.

# Examples

    let val = HeaderValue::from_str("hello").unwrap();
    assert_eq!(val, "hello");

An invalid value

    let val = HeaderValue::from_str("\n");
    assert!(val.is_err());

#### `pub fn from_name(name: HeaderName) -> HeaderValue` [src]

Converts a HeaderName into a HeaderValue

Since every valid HeaderName is a valid HeaderValue this is done infallibly.

# Examples

    let val = HeaderValue::from_name(ACCEPT);
    assert_eq!(val, HeaderValue::from_bytes(b"accept").unwrap());

#### `pub fn from_bytes(src: &[u8]) -> Result<HeaderValue, InvalidHeaderValue>` [src]

Attempt to convert a byte slice to a `HeaderValue`.

If the argument contains invalid header value bytes, an error is returned. Only byte values between 32 and 255 (inclusive) are permitted, excluding byte 127 (DEL).

This function is intended to be replaced in the future by a `TryFrom` implementation once the trait is stabilized in std.

# Examples

    let val = HeaderValue::from_bytes(b"hello\xfa").unwrap();
    assert_eq!(val, &b"hello\xfa"[..]);

An invalid value

    let val = HeaderValue::from_bytes(b"\n");
    assert!(val.is_err());

#### `pub fn from_maybe_shared<T>(src: T) -> Result<HeaderValue, InvalidHeaderValue> where
T: AsRef<[u8]> + 'static,` [src]

Attempt to convert a `Bytes` buffer to a `HeaderValue`.

This will try to prevent a copy if the type passed is the type used internally, and will copy the data if it is not.

#### `pub unsafe fn from_maybe_shared_unchecked<T>(src: T) -> HeaderValue where
T: AsRef<[u8]> + 'static,` [src]

Convert a `Bytes` directly into a `HeaderValue` without validating.

This function does NOT validate that illegal bytes are not contained within the buffer.

#### `pub fn to_str(&self) -> Result<&str, ToStrError>` [src]

Yields a `&str` slice if the `HeaderValue` only contains visible ASCII chars.

This function will perform a scan of the header value, checking all the characters.

# Examples

    let val = HeaderValue::from_static("hello");
    assert_eq!(val.to_str().unwrap(), "hello");

#### `pub fn len(&self) -> usize` [src]

Returns the length of `self`.

This length is in bytes.

# Examples

    let val = HeaderValue::from_static("hello");
    assert_eq!(val.len(), 5);

#### `pub fn is_empty(&self) -> bool` [src]

Returns true if the `HeaderValue` has a length of zero bytes.

# Examples

    let val = HeaderValue::from_static("");
    assert!(val.is_empty());

    let val = HeaderValue::from_static("hello");
    assert!(!val.is_empty());

#### `pub fn as_bytes(&self) -> &[u8]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
` [src]

Converts a `HeaderValue` to a byte slice.

# Examples

    let val = HeaderValue::from_static("hello");
    assert_eq!(val.as_bytes(), b"hello");

#### `pub fn set_sensitive(&mut self, val: bool)` [src]

Mark that the header value represents sensitive information.

# Examples

    let mut val = HeaderValue::from_static("my secret");

    val.set_sensitive(true);
    assert!(val.is_sensitive());

    val.set_sensitive(false);
    assert!(!val.is_sensitive());

#### `pub fn is_sensitive(&self) -> bool` [src]

Returns `true` if the value represents sensitive data.

Sensitive data could represent passwords or other data that should not be stored on disk or in memory. By marking header values as sensitive, components using this crate can be instructed to treat them with special care for security reasons. For example, caches can avoid storing sensitive values, and HPACK encoders used by HTTP/2.0 implementations can choose not to compress them.

Additionally, sensitive values will be masked by the `Debug` implementation of `HeaderValue`.

Note that sensitivity is not factored into equality or ordering.

# Examples

    let mut val = HeaderValue::from_static("my secret");

    val.set_sensitive(true);
    assert!(val.is_sensitive());

    val.set_sensitive(false);
    assert!(!val.is_sensitive());

## Trait Implementations

### `impl AsRef<[u8]> for HeaderValue` [src]

#### `pub fn as_ref(&self) -> &[u8]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
` [src]

Performs the conversion.

### `impl Clone for HeaderValue` [src]

#### `pub fn clone(&self) -> HeaderValue` [src]

Returns a copy of the value. Read more

#### `pub fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl Debug for HeaderValue` [src]

#### `pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>` [src]

Formats the value using the given formatter. Read more

### `impl Eq for HeaderValue` [src]

### `impl<'a> From<&'a HeaderValue> for HeaderValue` [src]

#### `pub fn from(t: &'a HeaderValue) -> HeaderValue` [src]

Performs the conversion.

### `impl From<HeaderName> for HeaderValue` [src]

#### `pub fn from(h: HeaderName) -> HeaderValue` [src]

Performs the conversion.

### `impl From<i16> for HeaderValue` [src]

#### `pub fn from(num: i16) -> HeaderValue` [src]

Performs the conversion.

### `impl From<i32> for HeaderValue` [src]

#### `pub fn from(num: i32) -> HeaderValue` [src]

Performs the conversion.

### `impl From<i64> for HeaderValue` [src]

#### `pub fn from(num: i64) -> HeaderValue` [src]

Performs the conversion.

### `impl From<isize> for HeaderValue` [src]

#### `pub fn from(num: isize) -> HeaderValue` [src]

Performs the conversion.

### `impl From<u16> for HeaderValue` [src]

#### `pub fn from(num: u16) -> HeaderValue` [src]

Performs the conversion.

### `impl From<u32> for HeaderValue` [src]

#### `pub fn from(num: u32) -> HeaderValue` [src]

Performs the conversion.

### `impl From<u64> for HeaderValue` [src]

#### `pub fn from(num: u64) -> HeaderValue` [src]

Performs the conversion.

### `impl From<usize> for HeaderValue` [src]

#### `pub fn from(num: usize) -> HeaderValue` [src]

Performs the conversion.

### `impl FromStr for HeaderValue` [src]

#### `type Err = InvalidHeaderValue`

The associated error which can be returned from parsing.

#### `pub fn from_str(s: &str) -> Result<HeaderValue, <HeaderValue as FromStr>::Err>` [src]

Parses a string `s` to return a value of this type. Read more

### `impl Hash for HeaderValue` [src]

#### `pub fn hash<__H>(&self, state: &mut __H) where
__H: Hasher,` [src]

Feeds this value into the given `Hasher`. Read more

#### `pub fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,` 1.3.0 [src]

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

### `impl Ord for HeaderValue` [src]

#### `pub fn cmp(&self, other: &HeaderValue) -> Ordering` [src]

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

#### `#[must_use]pub fn max(self, other: Self) -> Self` 1.21.0 [src]

Compares and returns the maximum of two values. Read more

#### `#[must_use]pub fn min(self, other: Self) -> Self` 1.21.0 [src]

Compares and returns the minimum of two values. Read more

#### `#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self` 1.50.0 [src]

Restrict a value to a certain interval. Read more

### `impl<'a, T> PartialEq<&'a T> for HeaderValue where
T: ?Sized,
HeaderValue: PartialEq<T>,` [src]

#### `pub fn eq(&self, other: &&'a T) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl PartialEq<[u8]> for HeaderValue` [src]

#### `pub fn eq(&self, other: &[u8]) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl PartialEq<HeaderValue> for [u8]` [src]

#### `pub fn eq(&self, other: &HeaderValue) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl PartialEq<HeaderValue> for HeaderValue` [src]

#### `pub fn eq(&self, other: &HeaderValue) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl<'a> PartialEq<HeaderValue> for &'a HeaderValue` [src]

#### `pub fn eq(&self, other: &HeaderValue) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl PartialEq<String> for HeaderValue` [src]

#### `pub fn eq(&self, other: &String) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl PartialEq<str> for HeaderValue` [src]

#### `pub fn eq(&self, other: &str) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl<'a, T> PartialOrd<&'a T> for HeaderValue where
T: ?Sized,
HeaderValue: PartialOrd<T>,` [src]

#### `pub fn partial_cmp(&self, other: &&'a T) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl PartialOrd<[u8]> for HeaderValue` [src]

#### `pub fn partial_cmp(&self, other: &[u8]) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl<'a> PartialOrd<HeaderValue> for &'a HeaderValue` [src]

#### `pub fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl PartialOrd<HeaderValue> for HeaderValue` [src]

#### `pub fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl PartialOrd<HeaderValue> for [u8]` [src]

#### `pub fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl PartialOrd<String> for HeaderValue` [src]

#### `pub fn partial_cmp(&self, other: &String) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl PartialOrd<str> for HeaderValue` [src]

#### `pub fn partial_cmp(&self, other: &str) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl<'a> TryFrom<&'a [u8]> for HeaderValue` [src]

#### `type Error = InvalidHeaderValue`

The type returned in the event of a conversion error.

#### `pub fn try_from(
t: &'a [u8]
) -> Result<HeaderValue, <HeaderValue as TryFrom<&'a [u8]>>::Error>` [src]

Performs the conversion.

### `impl<'a> TryFrom<&'a String> for HeaderValue` [src]

#### `type Error = InvalidHeaderValue`

The type returned in the event of a conversion error.

#### `pub fn try_from(
s: &'a String
) -> Result<HeaderValue, <HeaderValue as TryFrom<&'a String>>::Error>` [src]

Performs the conversion.

### `impl<'a> TryFrom<&'a str> for HeaderValue` [src]

#### `type Error = InvalidHeaderValue`

The type returned in the event of a conversion error.

#### `pub fn try_from(
t: &'a str
) -> Result<HeaderValue, <HeaderValue as TryFrom<&'a str>>::Error>` [src]

Performs the conversion.

### `impl TryFrom<String> for HeaderValue` [src]

#### `type Error = InvalidHeaderValue`

The type returned in the event of a conversion error.

#### `pub fn try_from(
t: String
) -> Result<HeaderValue, <HeaderValue as TryFrom<String>>::Error>` [src]

Performs the conversion.

### `impl TryFrom<Vec<u8, Global>> for HeaderValue` [src]

#### `type Error = InvalidHeaderValue`

The type returned in the event of a conversion error.

#### `pub fn try_from(
vec: Vec<u8, Global>
) -> Result<HeaderValue, <HeaderValue as TryFrom<Vec<u8, Global>>>::Error>` [src]

Performs the conversion.

## Auto Trait Implementations

### `impl RefUnwindSafe for HeaderValue`

### `impl Send for HeaderValue`

### `impl Sync for HeaderValue`

### `impl Unpin for HeaderValue`

### `impl UnwindSafe for HeaderValue`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<Q, K> Equivalent<K> for Q where
K: Borrow<Q> + ?Sized,
Q: Eq + ?Sized,` [src]

#### `pub fn equivalent(&self, key: &K) -> bool` [src]

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

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T> Instrument for T` [src]

#### `pub fn instrument(self, span: Span) -> Instrumented<Self>` [src]

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

#### `pub fn in_current_span(self) -> Instrumented<Self>` [src]

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

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `pub fn to_owned(&self) -> T` [src]

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

#### `pub fn clone_into(&self, target: &mut T)` [src]

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

recently added

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

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.