# struct HTTP::Headers

- HTTP::Headers
- Struct
- Value
- Object

##
Overview

A `Hash`-like object that holds HTTP headers.

Two headers are considered the same if their downcase representation is the same (in which `_` is the downcase version of `-`).

NOTE To use `Headers`, you must explicitly import it with `require "http/headers"`

##
Included Modules

- Enumerable({String, Array(String)})

##
Defined in:

http/headers.cr

##
Constructors

- .new

##
Macro Summary

- method_missing(call)

##
Instance Method Summary

- #==(other : self)

  Equality operator.

- #[](key) : String
- #[]=(key, value : String)
- #[]=(key, value : Array(String))
- #[]?(key) : String | Nil
- #add(key, value : String) : self

  Adds a header with key and value to the header set.

- #add(key, value : Array(String)) : self
- #add?(key, value : String) : Bool
- #add?(key, value : Array(String)) : Bool
- #clone
- #delete(key) : String | Nil
- #dup

  Returns a shallow copy of this object.

- #each(&)

  Must yield this collection's elements to the block.

- #empty? : Bool

  Returns `true` if `self` does not contain any element.

- #fetch(key, default) : String | Nil
- #fetch(key, &)
- #get(key) : Array(String)
- #get?(key) : Array(String) | Nil
- #has_key?(key) : Bool
- #hash(hasher)

  See `Object#hash(hasher)`

- #includes_word?(key, word) : Bool

  Returns if among the headers for key there is some that contains word as a value.

- #inspect(io : IO) : Nil

  Appends this struct's name and instance variables names and values to the given IO.

- #merge!(other) : self
- #pretty_print(pp)
- #same?(other : HTTP::Headers) : Bool
- #serialize(io : IO) : Nil

  Serializes headers according to the HTTP protocol.

- #serialize : String

  Serializes headers according to the HTTP protocol.

- #to_s(io : IO) : Nil

  Same as `#inspect(io)`.

- #valid_value?(value) : Bool

### Instance methods inherited from module `Enumerable({String, Array(String)})`

accumulate(initial : U) : Array(U) forall U
accumulate : Array({String, Array(String)})
accumulate(initial : U, &block : U, {String, Array(String)} -> U) : Array(U) forall U
accumulate(&block : {String, Array(String)}, {String, Array(String)} -> {String, Array(String)}) : Array({String, Array(String)}) accumulate, all?(& : {String, Array(String)} -> ) : Bool
all?(pattern) : Bool
all? : Bool all?, any?(& : {String, Array(String)} -> ) : Bool
any?(pattern) : Bool
any? : Bool any?, chunks(&block : {String, Array(String)} -> U) forall U chunks, compact_map(& : {String, Array(String)} -> _) compact_map, count(& : {String, Array(String)} -> ) : Int32
count(item) : Int32 count, cycle(n, & : {String, Array(String)} -> ) : Nil
cycle(& : {String, Array(String)} -> ) : Nil cycle, each(& : {String, Array(String)} -> ) each, each_cons(count : Int, reuse = false, &) each_cons, each_cons_pair(& : {String, Array(String)}, {String, Array(String)} -> ) : Nil each_cons_pair, each_slice(count : Int, reuse = false, &) each_slice, each_step(n : Int, *, offset : Int = 0, & : {String, Array(String)} -> ) : Nil each_step, each_with_index(offset = 0, &) each_with_index, each_with_object(obj : U, & : {String, Array(String)}, U -> ) : U forall U each_with_object, empty? : Bool empty?, find(if_none = nil, & : {String, Array(String)} -> ) find, find!(& : {String, Array(String)} -> ) : {String, Array(String)} find!, first(&)
first(count : Int) : Array({String, Array(String)})
first : {String, Array(String)} first, first? : {String, Array(String)} | Nil first?, flat_map(& : {String, Array(String)} -> _) flat_map, group_by(& : {String, Array(String)} -> U) forall U group_by, in_groups_of(size : Int, filled_up_with : U = nil) forall U
in_groups_of(size : Int, filled_up_with : U = nil, reuse = false, &) forall U in_groups_of, in_slices_of(size : Int) : Array(Array({String, Array(String)})) in_slices_of, includes?(obj) : Bool includes?, index(& : {String, Array(String)} -> ) : Int32 | Nil
index(obj) : Int32 | Nil index, index!(& : {String, Array(String)} -> ) : Int32
index!(obj) : Int32 index!, index_by(& : {String, Array(String)} -> U) : Hash(U, {String, Array(String)}) forall U index_by, join(io : IO, separator = "") : Nil
join(separator, io : IO) : Nil
join(separator = "") : String
join(io : IO, separator = "", & : {String, Array(String)}, IO -> )
join(separator, io : IO, &)
join(separator = "", & : {String, Array(String)} -> ) join, map(& : {String, Array(String)} -> U) : Array(U) forall U map, map_with_index(offset = 0, & : {String, Array(String)}, Int32 -> U) : Array(U) forall U map_with_index, max(count : Int) : Array({String, Array(String)})
max : {String, Array(String)} max, max? : {String, Array(String)} | Nil max?, max_by(& : {String, Array(String)} -> U) : {String, Array(String)} forall U max_by, max_by?(& : {String, Array(String)} -> U) : {String, Array(String)} | Nil forall U max_by?, max_of(& : {String, Array(String)} -> U) : U forall U max_of, max_of?(& : {String, Array(String)} -> U) : U | Nil forall U max_of?, min(count : Int) : Array({String, Array(String)})
min : {String, Array(String)} min, min? : {String, Array(String)} | Nil min?, min_by(& : {String, Array(String)} -> U) : {String, Array(String)} forall U min_by, min_by?(& : {String, Array(String)} -> U) : {String, Array(String)} | Nil forall U min_by?, min_of(& : {String, Array(String)} -> U) : U forall U min_of, min_of?(& : {String, Array(String)} -> U) : U | Nil forall U min_of?, minmax : Tuple({String, Array(String)}, {String, Array(String)}) minmax, minmax? : Tuple({String, Array(String)} | Nil, {String, Array(String)} | Nil) minmax?, minmax_by(& : {String, Array(String)} -> U) : Tuple({String, Array(String)}, {String, Array(String)}) forall U minmax_by, minmax_by?(& : {String, Array(String)} -> U) : Tuple({String, Array(String)}, {String, Array(String)}) | Tuple(Nil, Nil) forall U minmax_by?, minmax_of(& : {String, Array(String)} -> U) : Tuple(U, U) forall U minmax_of, minmax_of?(& : {String, Array(String)} -> U) : Tuple(U, U) | Tuple(Nil, Nil) forall U minmax_of?, none?(& : {String, Array(String)} -> ) : Bool
none?(pattern) : Bool
none? : Bool none?, one?(& : {String, Array(String)} -> ) : Bool
one?(pattern) : Bool
one? : Bool one?, partition(& : {String, Array(String)} -> ) : Tuple(Array({String, Array(String)}), Array({String, Array(String)}))
partition(type : U.class) forall U partition, present? : Bool present?, product(initial : Number)
product
product(initial : Number, & : {String, Array(String)} -> )
product(& : {String, Array(String)} -> _) product, reduce(memo, &)
reduce(&) reduce, reduce?(&) reduce?, reject(& : {String, Array(String)} -> )
reject(type : U.class) forall U
reject(pattern) : Array({String, Array(String)}) reject, sample(n : Int, random : Random = Random::DEFAULT) : Array({String, Array(String)})
sample(random : Random = Random::DEFAULT) : {String, Array(String)} sample, select(& : {String, Array(String)} -> )
select(type : U.class) : Array(U) forall U
select(pattern) : Array({String, Array(String)}) select, size : Int32 size, skip(count : Int) skip, skip_while(& : {String, Array(String)} -> ) : Array({String, Array(String)}) skip_while, sum(initial)
sum
sum(initial, & : {String, Array(String)} -> )
sum(& : {String, Array(String)} -> ) sum, take_while(& : {String, Array(String)} -> ) : Array({String, Array(String)}) take_while, tally(hash)
tally : Hash({String, Array(String)}, Int32) tally, tally_by(hash, &)
tally_by(&block : {String, Array(String)} -> U) : Hash(U, Int32) forall U tally_by, to_a : Array({String, Array(String)})
to_a(& : {String, Array(String)} -> U) : Array(U) forall U to_a, to_h
to_h(& : {String, Array(String)} -> Tuple(K, V)) forall K, V to_h, to_set : Set({String, Array(String)})
to_set(&block : {String, Array(String)} -> U) : Set(U) forall U to_set, zip(*others : Indexable | Iterable | Iterator, &)
zip(*others : Indexable | Iterable | Iterator) zip, zip?(*others : Indexable | Iterable | Iterator, &)
zip?(*others : Indexable | Iterable | Iterator) zip?

### Class methods inherited from module `Enumerable({String, Array(String)})`

element_type(x) element_type

### Instance methods inherited from struct `Struct`

==(other) : Bool ==, hash(hasher) hash, inspect(io : IO) : Nil inspect, pretty_print(pp) : Nil pretty_print, to_s(io : IO) : Nil to_s

### Instance methods inherited from struct `Value`

==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup

### Instance methods inherited from class `Object`

! : Bool !, !=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other) ===, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash hash, in?(collection : Object) : Bool
in?(*values : Object) : Bool in?, inspect(io : IO) : Nil
inspect : String inspect, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String to_json, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil to_pretty_json, to_s(io : IO) : Nil
to_s : String to_s, to_yaml(io : IO) : Nil
to_yaml : String to_yaml, try(&) try, unsafe_as(type : T.class) forall T unsafe_as

### Class methods inherited from class `Object`

from_json(string_or_io, root : String)
from_json(string_or_io) from_json, from_yaml(string_or_io : String | IO) from_yaml

### Macros inherited from class `Object`

class_getter(*names, &block) class_getter, class_getter!(*names) class_getter!, class_getter?(*names, &block) class_getter?, class_property(*names, &block) class_property, class_property!(*names) class_property!, class_property?(*names, &block) class_property?, class_setter(*names) class_setter, def_clone def_clone, def_equals(*fields) def_equals, def_equals_and_hash(*fields) def_equals_and_hash, def_hash(*fields) def_hash, delegate(*methods, to object) delegate, forward_missing_to(delegate) forward_missing_to, getter(*names, &block) getter, getter!(*names) getter!, getter?(*names, &block) getter?, property(*names, &block) property, property!(*names) property!, property?(*names, &block) property?, setter(*names) setter

##
Constructor Detail

def self.new #

##
Macro Detail

macro method_missing(call) #

##
Instance Method Detail

def ==(other : self) #

Equality operator.

Returns `true` if other is equal to `self`.

Keys are matched case-insensitive. String values are treated equal to an array values with the same string as single element.

    HTTP::Headers{"Foo" => "bar"} == HTTP::Headers{"Foo" => "bar"}   # => true
    HTTP::Headers{"Foo" => "bar"} == HTTP::Headers{"foo" => "bar"}   # => true
    HTTP::Headers{"Foo" => "bar"} == HTTP::Headers{"Foo" => ["bar"]} # => true
    HTTP::Headers{"Foo" => "bar"} == HTTP::Headers{"Foo" => "baz"}   # => false

def [](key) : String #
def []=(key, value : String) #
def []=(key, value : Array(String)) #
def []?(key) : String | Nil #
def add(key, value : String) : self #

Adds a header with key and value to the header set. If a header with key already exists in the set, value is appended to the existing header.

    require "http/headers"

    headers = HTTP::Headers.new
    headers.add("Connection", "keep-alive")
    headers["Connection"] # => "keep-alive"
    headers.add("Connection", "Upgrade")
    headers["Connection"] # => "keep-alive,Upgrade"

def add(key, value : Array(String)) : self #
def add?(key, value : String) : Bool #
def add?(key, value : Array(String)) : Bool #
def clone #
def delete(key) : String | Nil #
def dup #
Description copied from struct Value

Returns a shallow copy of this object.

Because `Value` is a value type, this method returns `self`, which already involves a shallow copy of this object because value types are passed by value.

def each(&) #
Description copied from module Enumerable({String, Array(String)})

Must yield this collection's elements to the block.

def empty? : Bool #
Description copied from module Enumerable({String, Array(String)})

Returns `true` if `self` does not contain any element.

    ([] of Int32).empty? # => true
    ([1]).empty?         # => false
    [nil, false].empty?  # => false

- `#present?` returns the inverse.

def fetch(key, default) : String | Nil #
def fetch(key, &) #
def get(key) : Array(String) #
def get?(key) : Array(String) | Nil #
def has_key?(key) : Bool #
def hash(hasher) #

See `Object#hash(hasher)`

def includes_word?(key, word) : Bool #

Returns if among the headers for key there is some that contains word as a value. The word is expected to match between word boundaries (i.e. non-alphanumeric chars).

    require "http/headers"

    headers = HTTP::Headers{"Connection" => "keep-alive, Upgrade"}
    headers.includes_word?("Connection", "Upgrade") # => true

def inspect(io : IO) : Nil #
Description copied from struct Struct

Appends this struct's name and instance variables names and values to the given IO.

    struct Point
      def initialize(@x : Int32, @y : Int32)
      end
    end

    p1 = Point.new 1, 2
    p1.to_s    # "Point(@x=1, @y=2)"
    p1.inspect # "Point(@x=1, @y=2)"

def merge!(other) : self #
def pretty_print(pp) #
def same?(other : HTTP::Headers) : Bool #
def serialize(io : IO) : Nil #

Serializes headers according to the HTTP protocol.

Prints a list of HTTP header fields in the format described in RFC 7230 §3.2, with each field terminated by a CRLF sequence (`"\r\n"`).

The serialization does not include a double CRLF sequence at the end.

    headers = HTTP::Headers{"foo" => "bar", "baz" => %w[qux qox]}
    headers.serialize # => "foo: bar\r\nbaz: qux\r\nbaz: qox\r\n"

def serialize : String #

Serializes headers according to the HTTP protocol.

Prints a list of HTTP header fields in the format described in RFC 7230 §3.2, with each field terminated by a CRLF sequence (`"\r\n"`).

The serialization does not include a double CRLF sequence at the end.

    headers = HTTP::Headers{"foo" => "bar", "baz" => %w[qux qox]}
    headers.serialize # => "foo: bar\r\nbaz: qux\r\nbaz: qox\r\n"

def to_s(io : IO) : Nil #
Description copied from struct Struct

Same as `#inspect(io)`.

def valid_value?(value) : Bool #