module Net::HTTPHeader - Documentation for Ruby 4.0
Description: module Net::HTTPHeader: The \HTTPHeader module provides access to \HTTP headers. HTTPRequest).
Keywords: ruby,module,Net::HTTPHeader

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# module Net::HTTPHeader

The HTTPHeader module provides access to HTTP headers.

The module is included in:

- `Net::HTTPGenericRequest` (and therefore `Net::HTTPRequest`).

- `Net::HTTPResponse`.

The headers are a hash-like collection of key/value pairs called fields.

## Request and Response Fields

Headers may be included in:

- A `Net::HTTPRequest` object: the object’s headers will be sent with the request. Any fields may be defined in the request; see Setters.

- A `Net::HTTPResponse` object: the objects headers are usually those returned from the host. Fields may be retrieved from the object; see Getters and Iterators.

Exactly which fields should be sent or expected depends on the host; see:

- Request fields.

- Response fields.

## About the Examples

Examples here assume that `net/http` has been required (which also requires `uri`):

    require 'net/http'

Many code examples here use these example websites:

- jsonplaceholder.typicode.com.

- example.com.

Some examples also assume these variables:

    uri = URI('https://jsonplaceholder.typicode.com/')
    uri.freeze # Examples may not modify.
    hostname = uri.hostname # => "jsonplaceholder.typicode.com"
    path = uri.path         # => "/"
    port = uri.port         # => 443

So that example requests may be written as:

    Net::HTTP.get(uri)
    Net::HTTP.get(hostname, '/index.html')
    Net::HTTP.start(hostname) do |http|
      http.get('/todos/1')
      http.get('/todos/2')
    end

An example that needs a modified `URI` first duplicates `uri`, then modifies the duplicate:

    _uri = uri.dup
    _uri.path = '/todos/1'

## Fields

A header field is a key/value pair.

### Field Keys

A field key may be:

- A string: Key `'Accept'` is treated as if it were `'Accept'.downcase`; i.e., `'accept'`.

- A symbol: Key `:Accept` is treated as if it were `:Accept.to_s.downcase`; i.e., `'accept'`.

Examples:

    req = Net::HTTP::Get.new(uri)
    req[:accept]  # => "*/*"
    req['Accept'] # => "*/*"
    req['ACCEPT'] # => "*/*"

    req['accept'] = 'text/html'
    req[:accept] = 'text/html'
    req['ACCEPT'] = 'text/html'

### Field Values

A field value may be returned as an array of strings or as a string:

- These methods return field values as arrays:

  - `get_fields`: Returns the array value for the given key, or `nil` if it does not exist.

  - `to_hash`: Returns a hash of all header fields: each key is a field name; its value is the array value for the field.

- These methods return field values as string; the string value for a field is equivalent to `self[key.downcase.to_s].join(', '))`:

  - `[]`: Returns the string value for the given key, or `nil` if it does not exist.

  - `fetch`: Like `[]`, but accepts a default value to be returned if the key does not exist.

The field value may be set:

- `[]=`: Sets the value for the given key; the given value may be a string, a symbol, an array, or a hash.

- `add_field`: Adds a given value to a value for the given key (not overwriting the existing value).

- `delete`: Deletes the field for the given key.

Example field values:

- String:

      req['Accept'] = 'text/html' # => "text/html"
      req['Accept']               # => "text/html"
      req.get_fields('Accept')    # => ["text/html"]

- Symbol:

      req['Accept'] = :text    # => :text
      req['Accept']            # => "text"
      req.get_fields('Accept') # => ["text"]

- Simple array:

      req[:foo] = %w[bar baz bat]
      req[:foo]            # => "bar, baz, bat"
      req.get_fields(:foo) # => ["bar", "baz", "bat"]

- Simple hash:

      req[:foo] = {bar: 0, baz: 1, bat: 2}
      req[:foo]            # => "bar, 0, baz, 1, bat, 2"
      req.get_fields(:foo) # => ["bar", "0", "baz", "1", "bat", "2"]

- Nested:

      req[:foo] = [%w[bar baz], {bat: 0, bam: 1}]
      req[:foo]            # => "bar, baz, bat, 0, bam, 1"
      req.get_fields(:foo) # => ["bar", "baz", "bat", "0", "bam", "1"]

      req[:foo] = {bar: %w[baz bat], bam: {bah: 0, bad: 1}}
      req[:foo]            # => "bar, baz, bat, bam, bah, 0, bad, 1"
      req.get_fields(:foo) # => ["bar", "baz", "bat", "bam", "bah", "0", "bad", "1"]

## Convenience Methods

Various convenience methods retrieve values, set values, query values, set form values, or iterate over fields.

### Setters

Method `[]=` can set any field, but does little to validate the new value; some of the other setter methods provide some validation:

- `[]=`: Sets the string or array value for the given key.

- `add_field`: Creates or adds to the array value for the given key.

- `basic_auth`: Sets the string authorization header for `'Authorization'`.

- `content_length=`: Sets the integer length for field `'Content-Length`.

- `content_type=`: Sets the string value for field `'Content-Type'`.

- `proxy_basic_auth`: Sets the string authorization header for `'Proxy-Authorization'`.

- `set_range`: Sets the value for field `'Range'`.

### Form Setters

- `set_form`: Sets an HTML form data set.

- `set_form_data`: Sets header fields and a body from HTML form data.

### Getters

Method `[]` can retrieve the value of any field that exists, but always as a string; some of the other getter methods return something different from the simple string value:

- `[]`: Returns the string field value for the given key.

- `content_length`: Returns the integer value of field `'Content-Length'`.

- `content_range`: Returns the `Range` value of field `'Content-Range'`.

- `content_type`: Returns the string value of field `'Content-Type'`.

- `fetch`: Returns the string field value for the given key.

- `get_fields`: Returns the array field value for the given `key`.

- `main_type`: Returns first part of the string value of field `'Content-Type'`.

- `sub_type`: Returns second part of the string value of field `'Content-Type'`.

- `range`: Returns an array of `Range` objects of field `'Range'`, or `nil`.

- `range_length`: Returns the integer length of the range given in field `'Content-Range'`.

- `type_params`: Returns the string parameters for `'Content-Type'`.

### Queries

- `chunked?`: Returns whether field `'Transfer-Encoding'` is set to `'chunked'`.

- `connection_close?`: Returns whether field `'Connection'` is set to `'close'`.

- `connection_keep_alive?`: Returns whether field `'Connection'` is set to `'keep-alive'`.

- `key?`: Returns whether a given key exists.

### Iterators

- `each_capitalized`: Passes each field capitalized-name/value pair to the block.

- `each_capitalized_name`: Passes each capitalized field name to the block.

- `each_header`: Passes each field name/value pair to the block.

- `each_name`: Passes each field name to the block.

- `each_value`: Passes each string field value to the block.

### Constants

MAX_FIELD_LENGTH

  The maximum length of `HTTP` header values.

MAX_KEY_LENGTH

  The maximum length of `HTTP` header keys.

### Public Instance Methods

[] (key)
Source

    # File lib/net/http/header.rb, line 226
    def [](key)
      a = @header[key.downcase.to_s] or return nil
      a.join(', ')
    end

Returns the string field value for the case-insensitive field `key`, or `nil` if there is no such key; see Fields:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['Connection'] # => "keep-alive"
    res['Nosuch']     # => nil

Note that some field values may be retrieved via convenience methods; see Getters.

[]= (key, val)
Source

    # File lib/net/http/header.rb, line 242
    def []=(key, val)
      unless val
        @header.delete key.downcase.to_s
        return val
      end
      set_field(key, val)
    end

Sets the value for the case-insensitive `key` to `val`, overwriting the previous value if the field exists; see Fields:

    req = Net::HTTP::Get.new(uri)
    req['Accept'] # => "*/*"
    req['Accept'] = 'text/html'
    req['Accept'] # => "text/html"

Note that some field values may be set via convenience methods; see Setters.

add_field (key, val)
Source

    # File lib/net/http/header.rb, line 263
    def add_field(key, val)
      stringified_downcased_key = key.downcase.to_s
      if @header.key?(stringified_downcased_key)
        append_field_value(@header[stringified_downcased_key], val)
      else
        set_field(key, val)
      end
    end

Adds value `val` to the value array for field `key` if the field exists; creates the field with the given `key` and `val` if it does not exist. see Fields:

    req = Net::HTTP::Get.new(uri)
    req.add_field('Foo', 'bar')
    req['Foo']            # => "bar"
    req.add_field('Foo', 'baz')
    req['Foo']            # => "bar, baz"
    req.add_field('Foo', %w[baz bam])
    req['Foo']            # => "bar, baz, baz, bam"
    req.get_fields('Foo') # => ["bar", "baz", "baz", "bam"]

basic_auth (account, password)
Source

    # File lib/net/http/header.rb, line 949
    def basic_auth(account, password)
      @header['authorization'] = [basic_encode(account, password)]
    end

Sets header `'Authorization'` using the given `account` and `password` strings:

    req.basic_auth('my_account', 'my_password')
    req['Authorization']
    # => "Basic bXlfYWNjb3VudDpteV9wYXNzd29yZA=="

canonical_each ()
Alias for: each_capitalized
chunked? ()
Source

    # File lib/net/http/header.rb, line 658
    def chunked?
      return false unless @header['transfer-encoding']
      field = self['Transfer-Encoding']
      (/(?:\A|[^\-\w])chunked(?![\-\w])/i =~ field) ? true : false
    end

Returns `true` if field `'Transfer-Encoding'` exists and has value `'chunked'`, `false` otherwise; see Transfer-Encoding response header:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['Transfer-Encoding'] # => "chunked"
    res.chunked?             # => true

connection_close? ()
Source

    # File lib/net/http/header.rb, line 970
    def connection_close?
      token = /(?:\A|,)\s*close\s*(?:\z|,)/i
      @header['connection']&.grep(token) {return true}
      @header['proxy-connection']&.grep(token) {return true}
      false
    end

Returns whether the `HTTP` session is to be closed.

connection_keep_alive? ()
Source

    # File lib/net/http/header.rb, line 978
    def connection_keep_alive?
      token = /(?:\A|,)\s*keep-alive\s*(?:\z|,)/i
      @header['connection']&.grep(token) {return true}
      @header['proxy-connection']&.grep(token) {return true}
      false
    end

Returns whether the `HTTP` session is to be kept alive.

content_length ()
Source

    # File lib/net/http/header.rb, line 620
    def content_length
      return nil unless key?('Content-Length')
      len = self['Content-Length'].slice(/\d+/) or
          raise Net::HTTPHeaderSyntaxError, 'wrong Content-Length format'
      len.to_i
    end

Returns the value of field `'Content-Length'` as an integer, or `nil` if there is no such field; see Content-Length request header:

    res = Net::HTTP.get_response(hostname, '/nosuch/1')
    res.content_length # => 2
    res = Net::HTTP.get_response(hostname, '/todos/1')
    res.content_length # => nil

content_length= (len)
Source

    # File lib/net/http/header.rb, line 641
    def content_length=(len)
      unless len
        @header.delete 'content-length'
        return nil
      end
      @header['content-length'] = [len.to_i.to_s]
    end

Sets the value of field `'Content-Length'` to the given numeric; see Content-Length response header:

    _uri = uri.dup
    hostname = _uri.hostname           # => "jsonplaceholder.typicode.com"
    _uri.path = '/posts'               # => "/posts"
    req = Net::HTTP::Post.new(_uri)    # => #<Net::HTTP::Post POST>
    req.body = '{"title": "foo","body": "bar","userId": 1}'
    req.content_length = req.body.size # => 42
    req.content_type = 'application/json'
    res = Net::HTTP.start(hostname) do |http|
      http.request(req)
    end # => #<Net::HTTPCreated 201 Created readbody=true>

content_range ()
Source

    # File lib/net/http/header.rb, line 674
    def content_range
      return nil unless @header['content-range']
      m = %r<\A\s*(\w+)\s+(\d+)-(\d+)/(\d+|\*)>.match(self['Content-Range']) or
          raise Net::HTTPHeaderSyntaxError, 'wrong Content-Range format'
      return unless m[1] == 'bytes'
      m[2].to_i .. m[3].to_i
    end

Returns a `Range` object representing the value of field `'Content-Range'`, or `nil` if no such field exists; see Content-Range response header:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['Content-Range'] # => nil
    res['Content-Range'] = 'bytes 0-499/1000'
    res['Content-Range'] # => "bytes 0-499/1000"
    res.content_range    # => 0..499

content_type ()
Source

    # File lib/net/http/header.rb, line 705
    def content_type
      main = main_type()
      return nil unless main

      sub = sub_type()
      if sub
        "#{main}/#{sub}"
      else
        main
      end
    end

Returns the media type from the value of field `'Content-Type'`, or `nil` if no such field exists; see Content-Type response header:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['content-type'] # => "application/json; charset=utf-8"
    res.content_type    # => "application/json"

content_type= (type, params = {})
Alias for: set_content_type
delete (key)
Source

    # File lib/net/http/header.rb, line 457
    def delete(key)
      @header.delete(key.downcase.to_s)
    end

Removes the header for the given case-insensitive `key` (see Fields); returns the deleted value, or `nil` if no such field exists:

    req = Net::HTTP::Get.new(uri)
    req.delete('Accept') # => ["*/*"]
    req.delete('Nosuch') # => nil

each ()
Alias for: each_header
each_capitalized () { |capitalize(k), join(', ')| ... }
Source

    # File lib/net/http/header.rb, line 488
    def each_capitalized
      block_given? or return enum_for(__method__) { @header.size }
      @header.each do |k,v|
        yield capitalize(k), v.join(', ')
      end
    end

Like `each_header`, but the keys are returned in capitalized form.

`Net::HTTPHeader#canonical_each` is an alias for `Net::HTTPHeader#each_capitalized`.

Also aliased as: canonical_each
each_capitalized_name () { |key| ... }
Source

    # File lib/net/http/header.rb, line 421
    def each_capitalized_name  #:yield: +key+
      block_given? or return enum_for(__method__) { @header.size }
      @header.each_key do |k|
        yield capitalize(k)
      end
    end

Calls the block with each capitalized field name:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res.each_capitalized_name do |key|
      p key if key.start_with?('C')
    end

Output:

    "Content-Type"
    "Connection"
    "Cache-Control"
    "Cf-Cache-Status"
    "Cf-Ray"

The capitalization is system-dependent; see Case Mapping.

Returns an enumerator if no block is given.

each_header () { |key| ... }
Source

    # File lib/net/http/header.rb, line 368
    def each_header   #:yield: +key+, +value+
      block_given? or return enum_for(__method__) { @header.size }
      @header.each do |k,va|
        yield k, va.join(', ')
      end
    end

Calls the block with each key/value pair:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res.each_header do |key, value|
      p [key, value] if key.start_with?('c')
    end

Output:

    ["content-type", "application/json; charset=utf-8"]
    ["connection", "keep-alive"]
    ["cache-control", "max-age=43200"]
    ["cf-cache-status", "HIT"]
    ["cf-ray", "771d17e9bc542cf5-ORD"]

Returns an enumerator if no block is given.

`Net::HTTPHeader#each` is an alias for `Net::HTTPHeader#each_header`.

Also aliased as: each
each_key ()
Alias for: each_name
each_name () { |key| ... }
Source

    # File lib/net/http/header.rb, line 395
    def each_name(&block)   #:yield: +key+
      block_given? or return enum_for(__method__) { @header.size }
      @header.each_key(&block)
    end

Calls the block with each field key:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res.each_key do |key|
      p key if key.start_with?('c')
    end

Output:

    "content-type"
    "connection"
    "cache-control"
    "cf-cache-status"
    "cf-ray"

Returns an enumerator if no block is given.

`Net::HTTPHeader#each_name` is an alias for `Net::HTTPHeader#each_key`.

Also aliased as: each_key
each_value () { |value| ... }
Source

    # File lib/net/http/header.rb, line 442
    def each_value   #:yield: +value+
      block_given? or return enum_for(__method__) { @header.size }
      @header.each_value do |va|
        yield va.join(', ')
      end
    end

Calls the block with each string field value:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res.each_value do |value|
      p value if value.start_with?('c')
    end

Output:

    "chunked"
    "cf-q-config;dur=6.0000002122251e-06"
    "cloudflare"

Returns an enumerator if no block is given.

fetch(key, default_val = nil) {|key| ... } → object
fetch(key, default_val = nil) → value or default_val
Source

    # File lib/net/http/header.rb, line 345
    def fetch(key, *args, &block)   #:yield: +key+
      a = @header.fetch(key.downcase.to_s, *args, &block)
      a.kind_of?(Array) ? a.join(', ') : a
    end

With a block, returns the string value for `key` if it exists; otherwise returns the value of the block; ignores the `default_val`; see Fields:

    res = Net::HTTP.get_response(hostname, '/todos/1')

    # Field exists; block not called.
    res.fetch('Connection') do |value|
      fail 'Cannot happen'
    end # => "keep-alive"

    # Field does not exist; block called.
    res.fetch('Nosuch') do |value|
      value.downcase
    end # => "nosuch"

With no block, returns the string value for `key` if it exists; otherwise, returns `default_val` if it was given; otherwise raises an exception:

    res.fetch('Connection', 'Foo') # => "keep-alive"
    res.fetch('Nosuch', 'Foo')     # => "Foo"
    res.fetch('Nosuch')            # Raises KeyError.

form_data= (params, sep = '&')
Alias for: set_form_data
get_fields (key)
Source

    # File lib/net/http/header.rb, line 310
    def get_fields(key)
      stringified_downcased_key = key.downcase.to_s
      return nil unless @header[stringified_downcased_key]
      @header[stringified_downcased_key].dup
    end

Returns the array field value for the given `key`, or `nil` if there is no such field; see Fields:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res.get_fields('Connection') # => ["keep-alive"]
    res.get_fields('Nosuch')     # => nil

key? (key)
Source

    # File lib/net/http/header.rb, line 467
    def key?(key)
      @header.key?(key.downcase.to_s)
    end

Returns `true` if the field for the case-insensitive `key` exists, `false` otherwise:

    req = Net::HTTP::Get.new(uri)
    req.key?('Accept') # => true
    req.key?('Nosuch') # => false

main_type ()
Source

    # File lib/net/http/header.rb, line 727
    def main_type
      return nil unless @header['content-type']
      self['Content-Type'].split(';').first.to_s.split('/')[0].to_s.strip
    end

Returns the leading (‘type’) part of the media type from the value of field `'Content-Type'`, or `nil` if no such field exists; see Content-Type response header:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['content-type'] # => "application/json; charset=utf-8"
    res.main_type       # => "application"

proxy_basic_auth (account, password)
Source

    # File lib/net/http/header.rb, line 960
    def proxy_basic_auth(account, password)
      @header['proxy-authorization'] = [basic_encode(account, password)]
    end

Sets header `'Proxy-Authorization'` using the given `account` and `password` strings:

    req.proxy_basic_auth('my_account', 'my_password')
    req['Proxy-Authorization']
    # => "Basic bXlfYWNjb3VudDpteV9wYXNzd29yZA=="

range ()
Source

    # File lib/net/http/header.rb, line 513
    def range
      return nil unless @header['range']

      value = self['Range']
      # byte-range-set = *( "," OWS ) ( byte-range-spec / suffix-byte-range-spec )
      #   *( OWS "," [ OWS ( byte-range-spec / suffix-byte-range-spec ) ] )
      # corrected collected ABNF
      # http://tools.ietf.org/html/draft-ietf-httpbis-p5-range-19#section-5.4.1
      # http://tools.ietf.org/html/draft-ietf-httpbis-p5-range-19#appendix-C
      # http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-19#section-3.2.5
      unless /\Abytes=((?:,[ \t]*)*(?:\d+-\d*|-\d+)(?:[ \t]*,(?:[ \t]*\d+-\d*|-\d+)?)*)\z/ =~ value
        raise Net::HTTPHeaderSyntaxError, "invalid syntax for byte-ranges-specifier: '#{value}'"
      end

      byte_range_set = $1
      result = byte_range_set.split(/,/).map {|spec|
        m = /(\d+)?\s*-\s*(\d+)?/i.match(spec) or
                raise Net::HTTPHeaderSyntaxError, "invalid byte-range-spec: '#{spec}'"
        d1 = m[1].to_i
        d2 = m[2].to_i
        if m[1] and m[2]
          if d1 > d2
            raise Net::HTTPHeaderSyntaxError, "last-byte-pos MUST greater than or equal to first-byte-pos but '#{spec}'"
          end
          d1..d2
        elsif m[1]
          d1..-1
        elsif m[2]
          -d2..-1
        else
          raise Net::HTTPHeaderSyntaxError, 'range is not specified'
        end
      }
      # if result.empty?
      # byte-range-set must include at least one byte-range-spec or suffix-byte-range-spec
      # but above regexp already denies it.
      if result.size == 1 && result[0].begin == 0 && result[0].end == -1
        raise Net::HTTPHeaderSyntaxError, 'only one suffix-byte-range-spec with zero suffix-length'
      end
      result
    end

Returns an array of `Range` objects that represent the value of field `'Range'`, or `nil` if there is no such field; see Range request header:

    req = Net::HTTP::Get.new(uri)
    req['Range'] = 'bytes=0-99,200-299,400-499'
    req.range # => [0..99, 200..299, 400..499]
    req.delete('Range')
    req.range # # => nil

range=
Alias for: set_range
range_length ()
Source

    # File lib/net/http/header.rb, line 691
    def range_length
      r = content_range() or return nil
      r.end - r.begin + 1
    end

Returns the integer representing length of the value of field `'Content-Range'`, or `nil` if no such field exists; see Content-Range response header:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['Content-Range'] # => nil
    res['Content-Range'] = 'bytes 0-499/1000'
    res.range_length     # => 500

set_content_type (type, params = {})
Source

    # File lib/net/http/header.rb, line 776
    def set_content_type(type, params = {})
      @header['content-type'] = [type + params.map{|k,v|"; #{k}=#{v}"}.join('')]
    end

Sets the value of field `'Content-Type'`; returns the new value; see Content-Type request header:

    req = Net::HTTP::Get.new(uri)
    req.set_content_type('application/json') # => ["application/json"]

`Net::HTTPHeader#content_type=` is an alias for `Net::HTTPHeader#set_content_type`.

Also aliased as: content_type=
set_form (params, enctype='application/x-www-form-urlencoded', formopt={})
Source

    # File lib/net/http/header.rb, line 928
    def set_form(params, enctype='application/x-www-form-urlencoded', formopt={})
      @body_data = params
      @body = nil
      @body_stream = nil
      @form_option = formopt
      case enctype
      when /\Aapplication\/x-www-form-urlencoded\z/i,
        /\Amultipart\/form-data\z/i
        self.content_type = enctype
      else
        raise ArgumentError, "invalid enctype: #{enctype}"
      end
    end

Stores form data to be used in a `POST` or `PUT` request.

The form data given in `params` consists of zero or more fields; each field is:

- A scalar value.

- A name/value pair.

- An `IO` stream opened for reading.

Argument `params` should be an Enumerable (method `params.map` will be called), and is often an array or hash.

First, we set up a request:

    _uri = uri.dup
    _uri.path ='/posts'
    req = Net::HTTP::Post.new(_uri)

Argument `params` As an Array

When `params` is an array, each of its elements is a subarray that defines a field; the subarray may contain:

- One string:

      req.set_form([['foo'], ['bar'], ['baz']])

- Two strings:

      req.set_form([%w[foo 0], %w[bar 1], %w[baz 2]])

- When argument `enctype` (see below) is given as `'multipart/form-data'`:

  - A string name and an `IO` stream opened for reading:

        require 'stringio'
        req.set_form([['file', StringIO.new('Ruby is cool.')]])

  - A string name, an `IO` stream opened for reading, and an options hash, which may contain these entries:

    - `:filename`: The name of the file to use.

    - `:content_type`: The content type of the uploaded file.

    Example:

        req.set_form([['file', file, {filename: "other-filename.foo"}]]

The various forms may be mixed:

    req.set_form(['foo', %w[bar 1], ['file', file]])

Argument `params` As a Hash

When `params` is a hash, each of its entries is a name/value pair that defines a field:

- The name is a string.

- The value may be:

  - `nil`.

  - Another string.

  - An `IO` stream opened for reading (only when argument `enctype` – see below – is given as `'multipart/form-data'`).

Examples:

    # Nil-valued fields.
    req.set_form({'foo' => nil, 'bar' => nil, 'baz' => nil})

    # String-valued fields.
    req.set_form({'foo' => 0, 'bar' => 1, 'baz' => 2})

    # IO-valued field.
    require 'stringio'
    req.set_form({'file' => StringIO.new('Ruby is cool.')})

    # Mixture of fields.
    req.set_form({'foo' => nil, 'bar' => 1, 'file' => file})

Optional argument `enctype` specifies the value to be given to field `'Content-Type'`, and must be one of:

- `'application/x-www-form-urlencoded'` (the default).

- `'multipart/form-data'`; see RFC 7578.

Optional argument `formopt` is a hash of options (applicable only when argument `enctype` is `'multipart/form-data'`) that may include the following entries:

- `:boundary`: The value is the boundary string for the multipart message. If not given, the boundary is a random string. See Boundary.

- `:charset`: Value is the character set for the form submission. Field names and values of non-file fields should be encoded with this charset.

set_form_data (params, sep = '&')
Source

    # File lib/net/http/header.rb, line 816
    def set_form_data(params, sep = '&')
      query = URI.encode_www_form(params)
      query.gsub!(/&/, sep) if sep != '&'
      self.body = query
      self.content_type = 'application/x-www-form-urlencoded'
    end

Sets the request body to a URL-encoded string derived from argument `params`, and sets request header field `'Content-Type'` to `'application/x-www-form-urlencoded'`.

The resulting request is suitable for `HTTP` request `POST` or `PUT`.

Argument `params` must be suitable for use as argument `enum` to `URI.encode_www_form`.

With only argument `params` given, sets the body to a URL-encoded string with the default separator `'&'`:

    req = Net::HTTP::Post.new('example.com')

    req.set_form_data(q: 'ruby', lang: 'en')
    req.body            # => "q=ruby&lang=en"
    req['Content-Type'] # => "application/x-www-form-urlencoded"

    req.set_form_data([['q', 'ruby'], ['lang', 'en']])
    req.body            # => "q=ruby&lang=en"

    req.set_form_data(q: ['ruby', 'perl'], lang: 'en')
    req.body            # => "q=ruby&q=perl&lang=en"

    req.set_form_data([['q', 'ruby'], ['q', 'perl'], ['lang', 'en']])
    req.body            # => "q=ruby&q=perl&lang=en"

With string argument `sep` also given, uses that string as the separator:

    req.set_form_data({q: 'ruby', lang: 'en'}, '|')
    req.body # => "q=ruby|lang=en"

`Net::HTTPHeader#form_data=` is an alias for `Net::HTTPHeader#set_form_data`.

Also aliased as: form_data=
set_range(length) → length
set_range(offset, length) → range
set_range(begin..length) → range
Source

    # File lib/net/http/header.rb, line 580
    def set_range(r, e = nil)
      unless r
        @header.delete 'range'
        return r
      end
      r = (r...r+e) if e
      case r
      when Numeric
        n = r.to_i
        rangestr = (n > 0 ? "0-#{n-1}" : "-#{-n}")
      when Range
        first = r.first
        last = r.end
        last -= 1 if r.exclude_end?
        if last == -1
          rangestr = (first > 0 ? "#{first}-" : "-#{-first}")
        else
          raise Net::HTTPHeaderSyntaxError, 'range.first is negative' if first < 0
          raise Net::HTTPHeaderSyntaxError, 'range.last is negative' if last < 0
          raise Net::HTTPHeaderSyntaxError, 'must be .first < .last' if first > last
          rangestr = "#{first}-#{last}"
        end
      else
        raise TypeError, 'Range/Integer is required'
      end
      @header['range'] = ["bytes=#{rangestr}"]
      r
    end

Sets the value for field `'Range'`; see Range request header:

With argument `length`:

    req = Net::HTTP::Get.new(uri)
    req.set_range(100)      # => 100
    req['Range']            # => "bytes=0-99"

With arguments `offset` and `length`:

    req.set_range(100, 100) # => 100...200
    req['Range']            # => "bytes=100-199"

With argument `range`:

    req.set_range(100..199) # => 100..199
    req['Range']            # => "bytes=100-199"

`Net::HTTPHeader#range=` is an alias for `Net::HTTPHeader#set_range`.

Also aliased as: range=
sub_type ()
Source

    # File lib/net/http/header.rb, line 742
    def sub_type
      return nil unless @header['content-type']
      _, sub = *self['Content-Type'].split(';').first.to_s.split('/')
      return nil unless sub
      sub.strip
    end

Returns the trailing (‘subtype’) part of the media type from the value of field `'Content-Type'`, or `nil` if no such field exists; see Content-Type response header:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['content-type'] # => "application/json; charset=utf-8"
    res.sub_type        # => "json"

to_hash ()
Source

    # File lib/net/http/header.rb, line 481
    def to_hash
      @header.dup
    end

Returns a hash of the key/value pairs:

    req = Net::HTTP::Get.new(uri)
    req.to_hash
    # =>
    {"accept-encoding"=>["gzip;q=1.0,deflate;q=0.6,identity;q=0.3"],
     "accept"=>["*/*"],
     "user-agent"=>["Ruby"],
     "host"=>["jsonplaceholder.typicode.com"]}

type_params ()
Source

    # File lib/net/http/header.rb, line 757
    def type_params
      result = {}
      list = self['Content-Type'].to_s.split(';')
      list.shift
      list.each do |param|
        k, v = *param.split('=', 2)
        result[k.strip] = v.strip
      end
      result
    end

Returns the trailing (‘parameters’) part of the value of field `'Content-Type'`, or `nil` if no such field exists; see Content-Type response header:

    res = Net::HTTP.get_response(hostname, '/todos/1')
    res['content-type'] # => "application/json; charset=utf-8"
    res.type_params     # => {"charset"=>"utf-8"}