HTTP Messages

The Message class provides an interface to the portions of an HTTP message that are common to both requests and responses, including the message body, protocol version, utilities for working with the headers, and methods for handling content negotiation.

This class is the parent class that both the Request Class and the Response Class extend from. As such, some methods, such as the content negotiation methods, may apply only to a request or response, and not the other one, but they have been included here to keep the header methods together.

What is Content Negotiation?

At it’s heart Content Negotiation is simply a part of the HTTP specification that allows a single resource to serve more than one type of content, allowing the clients to request the type of data that works best for them.

A classic example of this is a browser that cannot display PNG files can request only GIF or JPEG images. When the getServer receives the request, it looks at the available file types the client is requesting and selects the best match from the image formats that it supports, in this case likely choosing a JPEG image to return.

This same negotiation can happen with four types of data:

  • Media/Document Type - this could be image format, or HTML vs. XML or JSON.
  • Character Set - The character set the returned document should be set in. Typically is UTF-8.
  • Document Encoding - Typically the type of compression used on the results.
  • Document Language - For sites that support multiple languages, this helps determine which to return.

Class Reference

CodeIgniter\HTTP\Message
getBody()
Returns:The current message body
Return type:mixed

Returns the current message body, if any has been set. If not body exists, returns null:

echo $message->getBody();
setBody($data)
Parameters:
  • $data (mixed) – The body of the message.
Returns:

the Message|Response instance to allow methods to be chained together.
Return type:

CodeIgniter\HTTP\Message|CodeIgniter\HTTP\Response

Sets the body of the current request.

appendBody($data)
Parameters:
  • $data (mixed) – The body of the message.
Returns:

the Message|Response instance to allow methods to be chained together.
Return type:

CodeIgniter\HTTP\Message|CodeIgniter\HTTP\Response

Appends data to the body of the current request.

populateHeaders()
Returns:void

Scans and parses the headers found in the SERVER data and stores it for later access. This is used by the IncomingRequest Class to make the current request’s headers available.

The headers are any SERVER data that starts with HTTP_, like HTTP_HOST. Each message is converted from it’s standard uppercase and underscore format to a ucwords and dash format. The preceding HTTP_ is removed from the string. So HTTP_ACCEPT_LANGUAGE becomes Accept-Language.

getHeaders()
Returns:An array of all of the headers found.
Return type:array

Returns an array of all headers found or previously set.

getHeader($name)
Parameters:
  • $name (string) – The name of the header you want to retrieve the value of.
Returns:

Returns a single header object. If multiple headers with the same name exist, then will return an array of header objects.
Return type:

CodeIgniter\HTTP\Header|array

Allows you to retrieve the current value of a single message header. $name is the case-insensitive header name. While the header is converted internally as described above, you can access the header with any type of case:

// These are all the same:
$message->getHeader('HOST');
$message->getHeader('Host');
$message->getHeader('host');

If the header has multiple values, getValue() will return as an array of values. You can use the getValueLine() method to retrieve the values as a string:

echo $message->getHeader('Accept-Language');

// Outputs something like:
'Accept-Language: en,en-US'

echo $message->getHeader('Accept-Language')->getValue();

// Outputs something like:
[
    'en',
    'en-US'
]

echo $message->getHeader('Accept-Language')->getValueLine();

// Outputs something like:
'en,en-US'

You can filter the header by passing a filter value in as the second parameter:

$message->getHeader('Document-URI', FILTER_SANITIZE_URL);
hasHeader($name)
Parameters:
  • $name (string) – The name of the header you want to see if it exists.
Returns:

Returns TRUE if it exists, FALSE otherwise.
Return type:

bool
getHeaderLine($name)
Parameters:
  • $name (string) – The name of the header to retrieve.
Returns:

A string representing the header value.
Return type:

string

Returns the value(s) of the header as a string. This method allows you to easily get a string representation of the header values when the header has multiple values. The values are appropriately joined:

echo $message->getHeaderLine('Accept-Language');

// Outputs:
en, en-US
setHeader($name, $value)
Parameters:
  • $name (string) – The name of the header to set the value for.
  • $value (mixed) – The value to set the header to.
Returns:

The current Message|Response instance
Return type:

CodeIgniter\HTTP\Message|CodeIgniter\HTTP\Response

Sets the value of a single header. $name is the case-insensitive name of the header. If the header doesn’t already exist in the collection, it will be created. The $value can be either a string or an array of strings:

$message->setHeader('Host', 'codeigniter.com');
removeHeader($name)
Parameters:
  • $name (string) – The name of the header to remove.
Returns:

The current message instance
Return type:

CodeIgniter\HTTP\Message

Removes the header from the Message. $name is the case-insensitive name of the header:

$message->removeHeader('Host');
appendHeader($name, $value)
Parameters:
  • $name (string) – The name of the header to modify
  • $value (string) – The value to add to the header.
Returns:

The current message instance
Return type:

CodeIgniter\HTTP\Message

Adds a value to an existing header. The header must already be an array of values instead of a single string. If it is a string then a LogicException will be thrown.

$message->appendHeader('Accept-Language', 'en-US; q=0.8');
prependHeader($name, $value)
Parameters:
  • $name (string) – The name of the header to modify
  • $value (string) – The value to prepend to the header.
Returns:

The current message instance
Return type:

CodeIgniter\HTTP\Message

Prepends a value to an existing header. The header must already be an array of values instead of a single string. If it is a string then a LogicException will be thrown.

$message->prependHeader('Accept-Language', 'en,');
getProtocolVersion()
Returns:The current HTTP protocol version
Return type:string

Returns the message’s current HTTP protocol. If none has been set, will return null. Acceptable values are 1.0, 1.1 and 2.0.

setProtocolVersion($version)
Parameters:
  • $version (string) – The HTTP protocol version
Returns:

The current message instance
Return type:

CodeIgniter\HTTP\Message

Sets the HTTP protocol version this Message uses. Valid values are 1.0, 1.1 and 2.0:

$message->setProtocolVersion('1.1');