The Headers Class

Overview

The Zend\Http\Headers class is a container for HTTP headers. It is typically accessed as part of a Zend\Http\Request or Zend\Http\Response getHeaders() call. The Headers container will lazily load actual Header objects as to reduce the overhead of header specific parsing.

The Zend\Http\Header\* classes are the domain specific implementations for the various types of Headers that one might encounter during the typical HTTP request. If a header of unknown type is encountered, it will be implemented as a Zend\Http\Header\GenericHeader instance. See the below table for a list of the various HTTP headers and the API that is specific to each header type.

Quick Start

The quickest way to get started interacting with header objects is by getting an already populated Headers container from a request or response object.

// $client is an instance of Zend\Http\Client

// You can retrieve the request headers by first retrieving
// the Request object and then calling getHeaders on it
$requestHeaders  = $client->getRequest()->getHeaders();

// The same method also works for retrieving Response headers
$responseHeaders = $client->getResponse()->getHeaders();

Zend\Http\Headers can also extract headers from a string:

$headerString = <<<EOB
Host: www.example.com
Content-Type: text/html
Content-Length: 1337
EOB;

$headers = Zend\Http\Headers::fromString($headerString);
// $headers is now populated with three objects
//   (1) Zend\Http\Header\Host
//   (2) Zend\Http\Header\ContentType
//   (3) Zend\Http\Header\ContentLength

Now that you have an instance of Zend\Http\Headers you can manipulate the individual headers it contains using the provided public API methods outlined in the “Available Methods” section.

Configuration Options

No configuration options are available.

Available Methods

Headers::fromString

Headers::fromString(string $string)

Populates headers from string representation

Parses a string for headers, and aggregates them, in order, in the current instance, primarily as strings until they are needed (they will be lazy loaded).

Returns Zend\Http\Headers

setPluginClassLoader

setPluginClassLoader(Zend\Loader\PluginClassLocator $pluginClassLoader)

Set an alternate implementation for the plugin class loader

Returns Zend\Http\Headers

getPluginClassLoader

getPluginClassLoader()

Return an instance of a Zend\Loader\PluginClassLocator, lazyload and inject map if necessary.

Returns Zend\Loader\PluginClassLocator

addHeaders

addHeaders(array|Traversable $headers)

Add many headers at once

Expects an array (or Traversable object) of type/value pairs.

Returns Zend\Http\Headers

addHeaderLine

addHeaderLine(string $headerFieldNameOrLine, string $fieldValue)

Add a raw header line, either in name => value, or as a single string ‘name: value’

This method allows for lazy-loading in that the parsing and instantiation of Header object will be delayed until they are retrieved by either get() or current().

Returns Zend\Http\Headers

addHeader

addHeader(Zend\Http\Header\HeaderInterface $header)

Add a Header to this container, for raw values see addHeaderLine() and addHeaders().

Returns Zend\Http\Headers

removeHeader

removeHeader(Zend\Http\Header\HeaderInterface $header)

Remove a Header from the container

Returns bool

clearHeaders

clearHeaders()

Clear all headers

Removes all headers from queue

Returns Zend\Http\Headers

get

get(string $name)

Get all headers of a certain name/type

Returns false| Zend\Http\Header\HeaderInterface| ArrayIterator

has

has(string $name)

Test for existence of a type of header

Returns bool

next

next()

Advance the pointer for this object as an iterator

Returns void

key

key()

Return the current key for this object as an iterator

Returns mixed

valid

valid()

Is this iterator still valid?

Returns bool

rewind

rewind()

Reset the internal pointer for this object as an iterator

Returns void

current

current()

Return the current value for this iterator, lazy loading it if need be

Returns Zend\Http\Header\HeaderInterface

count

count()

Return the number of headers in this container. If all headers have not been parsed, actual count could increase if MultipleHeader objects exist in the Request/Response. If you need an exact count, iterate.

Returns int

toString

toString()

Render all headers at once

This method handles the normal iteration of headers; it is up to the concrete classes to prepend with the appropriate status/request line.

Returns string

toArray

toArray()

Return the headers container as an array

Returns array

forceLoading

forceLoading()

By calling this, it will force parsing and loading of all headers, after this count() will be accurate

Returns bool

Zend\Http\Header\* Base Methods

fromString

fromString(string $headerLine)

Factory to generate a header object from a string

Returns Zend\Http\Header\GenericHeader

getFieldName

getFieldName()

Retrieve header field name

Returns string

getFieldValue

getFieldValue()

Retrieve header field value

Returns string

toString

toString()

Cast to string as a well formed HTTP header line

Returns in form of “NAME: VALUE\r\n”

Returns string

List of HTTP Header Types

Zend\Http\Header\* Classes

Class Name	Additional Methods
Accept	N/A
AcceptCharset	N/A
AcceptEncoding	N/A
AcceptLanguage	N/A
AcceptRanges	getRangeUnit() / setRangeUnit() - The range unit of the accept ranges header
Age	getDeltaSeconds() / setDeltaSeconds() - The age in delta seconds
Allow	getAllowedMethods() / setAllowedMethods() - An array of allowed methods
AuthenticationInfo	N/A
Authorization	N/A
CacheControl	N/A
Connection	N/A
ContentDisposition	N/A
ContentEncoding	N/A
ContentLanguage	N/A
ContentLength	N/A
ContentLocation	N/A
ContentMD5	N/A
ContentRange	N/A
ContentType	N/A
Cookie	Extends \ArrayObject setEncodeValue() / getEncodeValue() - Whether or not to encode values
Date	N/A
Etag	N/A
Expect	N/A
Expires	N/A
From	N/A
Host	N/A
IfMatch	N/A
IfModifiedSince	N/A
IfNoneMatch	N/A
IfRange	N/A
IfUnmodifiedSince	N/A
KeepAlive	N/A
LastModified	N/A
Location	N/A
MaxForwards	N/A
Pragma	N/A
ProxyAuthenticate	N/A
ProxyAuthorization	N/A
Range	N/A
Referer	N/A
Refresh	N/A
RetryAfter	N/A
Server	N/A
SetCookie	getName() / setName() - The cookie name getValue() / setValue() - The cookie value getExpires() / setExpires() - The time frame the cookie is valid for, null is a session cookie getPath() / setPath() - The uri path the cookie is bound to getDomain() / setDomain() - The domain the cookie applies to getMaxAge() / setMaxAge() - The maximum age of the cookie getVersion() / setVersion() - The cookie version isSecure() / setSecure() - Whether the cookies contains the Secure flag isHttponly() / setHttponly() - Whether the cookies can be accessed via HTTP only isSessionCookie() - Whether the cookie is a session cookie isExpired() - Whether the cookie is expired isValidForRequest() - Whether the cookie is valid for a given request domain, path and isSecure
TE	N/A
Trailer	N/A
TransferEncoding	N/A
Upgrade	N/A
UserAgent	N/A
Vary	N/A
Via	N/A
Warning	N/A
WWWAuthenticate	N/A

Examples

Retrieving headers from a Zend\Http\Headers object

// $client is an instance of Zend\Http\Client
$response = $client->send();
$headers = $response->getHeaders();

// We can check if the Request contains a specific header by
// using the ``has`` method. Returns boolean ``TRUE`` if at least
// one matching header found, and ``FALSE`` otherwise
$headers->has('Content-Type');

// We can retrieve all instances of a specific header by using
// the ``get`` method:
$contentTypeHeaders = $headers->get('Content-Type');

There are three possibilities for the return value of the above call to the get method:

• If no Content-Type header was set in the Request, get will return false.
• If only one Content-Type header was set in the Request, get will return an instance of Zend\Http\Header\ContentType.
• If more than one Content-Type header was set in the Request, get will return an ArrayIterator containing one Zend\Http\Header\ContentType instance per header.

Adding headers to a Zend\Http\Headers object

$headers = new Zend\Http\Headers();

// We can directly add any object that implements Zend\Http\Header\HeaderInterface
$typeHeader = Zend\Http\Header\ContentType::fromString('Content-Type: text/html');
$headers->addHeader($typeHeader);

// We can add headers using the raw string representation, either
// passing the header name and value as separate arguments...
$headers->addHeaderLine('Content-Type', 'text/html');

// .. or we can pass the entire header as the only argument
$headers->addHeaderLine('Content-Type: text/html');

// We can also add headers in bulk using addHeaders, which accepts
// an array of individual header definitions that can be in any of
// the accepted formats outlined below:
$headers->addHeaders(array(

    // An object implementing Zend\Http\Header\HeaderInterface
    Zend\Http\Header\ContentType::fromString('Content-Type: text/html'),

    // A raw header string
    'Content-Type: text/html',

    // We can also pass the header name as the array key and the
    // header content as that array key's value
    'Content-Type' => 'text/html');

));

Removing headers from a Zend\Http\Headers object

We can remove all headers of a specific type using the removeHeader method, which accepts a single object implementing Zend\Http\Header\HeaderInterface

// $headers is a pre-configured instance of Zend\Http\Headers

// We can also delete individual headers or groups of headers
$matches = $headers->get('Content-Type');

// If more than one header was found, iterate over the collection
// and remove each one individually
if ($matches instanceof ArrayIterator) {
    foreach ($headers as $header) {
        $headers->removeHeader($header);
    }
// If only a single header was found, remove it directly
} elseif ($matches instanceof Zend\Http\Header\HeaderInterface) {
    $headers->removeHeader($header);
}

// In addition to this, we can clear all the headers currently stored in
// the container by calling the clearHeaders() method
$matches->clearHeaders();