Struct Header 

pub struct Header<E> { /* private fields */ }

Extracts header values as cache key parts.

Supports flexible header selection, value extraction, and transformation.

Key Parts Generated

For each matched header, generates a KeyPart with:

• Key: the header name
• Value: the extracted (and optionally transformed) value

Implementations

impl<S> Header<NeutralExtractor<S>>

pub fn new(name: String) -> Self

Creates a header extractor for a single header by exact name.

The header value becomes a cache key part with the header name as key. For more complex extraction (prefix matching, regex, transforms), use Header::new_with.

Chain onto existing extractors using HeaderExtractor::header instead if you already have an extractor chain.

impl<E> Header<E>

pub fn new_with( inner: E, name_selector: NameSelector, value_extractor: ValueExtractor, transforms: Vec<Transform>, ) -> Self

Creates a header extractor with full configuration options.

This constructor provides complete control over header extraction:

• Select headers by exact name or prefix pattern
• Extract full values or use regex capture groups
• Apply transformations (hash, lowercase, uppercase)

For simple exact-name extraction without transforms, use Header::new or HeaderExtractor::header instead.

Trait Implementations

impl<E: Debug> Debug for Header<E>

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

Formats the value using the given formatter.

impl<ReqBody, E> Extractor for Header<E>

where ReqBody: Body + Send + 'static, ReqBody::Error: Send, E: Extractor<Subject = CacheableHttpRequest<ReqBody>> + Send + Sync,

type Subject = <E as Extractor>::Subject

The type from which cache key components are extracted.

fn get<'life0, 'async_trait>( &'life0 self, subject: Self::Subject, ) -> Pin<Box<dyn Future<Output = KeyParts<Self::Subject>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Extract cache key components from the subject.