class ActionDispatch::Http::Headers

Action Dispatch HTTP Headers¶ ↑

Provides access to the request’s HTTP headers from the environment.

env     = { "CONTENT_TYPE" => "text/plain", "HTTP_USER_AGENT" => "curl/7.43.0" }
headers = ActionDispatch::Http::Headers.from_hash(env)
headers["Content-Type"] # => "text/plain"
headers["User-Agent"] # => "curl/7.43.0"

Also note that when headers are mapped to CGI-like variables by the Rack server, both dashes and underscores are converted to underscores. This ambiguity cannot be resolved at this stage anymore. Both underscores and dashes have to be interpreted as if they were originally sent as dashes.

# GET / HTTP/1.1
# ...
# User-Agent: curl/7.43.0
# X_Custom_Header: token

headers["X_Custom_Header"] # => nil
headers["X-Custom-Header"] # => "token"

Constants

CGI_VARIABLES
HTTP_HEADER

Public Class Methods

from_hash (hash)

# File actionpack/lib/action_dispatch/http/headers.rb, line 52
def self.from_hash(hash)
  new ActionDispatch::Request.new hash
end

Public Instance Methods

[] (key)

Returns the value for the given key mapped to @env.

# File actionpack/lib/action_dispatch/http/headers.rb, line 61
def [](key)
  @req.get_header env_name(key)
end

[]= (key, value)

Sets the given value for the key mapped to @env.

# File actionpack/lib/action_dispatch/http/headers.rb, line 66
def []=(key, value)
  @req.set_header env_name(key), value
end

add (key, value)

Add a value to a multivalued header like Vary or Accept-Encoding.

# File actionpack/lib/action_dispatch/http/headers.rb, line 71
def add(key, value)
  @req.add_header env_name(key), value
end

each (&block)

# File actionpack/lib/action_dispatch/http/headers.rb, line 97
def each(&block)
  @req.each_header(&block)
end

env ()

# File actionpack/lib/action_dispatch/http/headers.rb, line 118
def env; @req.env.dup; end

fetch (key, default = DEFAULT) { || ... }

Returns the value for the given key mapped to @env.

If the key is not found and an optional code block is not provided, raises a KeyError exception.

If the code block is provided, then it will be run and its result returned.

# File actionpack/lib/action_dispatch/http/headers.rb, line 89
def fetch(key, default = DEFAULT)
  @req.fetch_header(env_name(key)) do
    return default unless default == DEFAULT
    return yield if block_given?
    raise KeyError, key
  end
end

include? (key)

Alias for: key?

key? (key)

# File actionpack/lib/action_dispatch/http/headers.rb, line 75
def key?(key)
  @req.has_header? env_name(key)
end

Also aliased as: include?

merge (headers_or_env)

Returns a new Http::Headers instance containing the contents of headers_or_env and the original instance.

# File actionpack/lib/action_dispatch/http/headers.rb, line 103
def merge(headers_or_env)
  headers = @req.dup.headers
  headers.merge!(headers_or_env)
  headers
end

merge! (headers_or_env)

Adds the contents of headers_or_env to original instance entries; duplicate keys are overwritten with the values from headers_or_env.

# File actionpack/lib/action_dispatch/http/headers.rb, line 112
def merge!(headers_or_env)
  headers_or_env.each do |key, value|
    @req.set_header env_name(key), value
  end
end