View Helper - Links

Introduction

The links helper is used for rendering HTML LINK elements. Links are used for describing document relationships of the currently active page. Read more about links and link types at Document relationships: the LINK element (HTML4 W3C Rec.) and Link types (HTML4 W3C Rec.) in the HTML4 W3C Recommendation.

There are two types of relations; forward and reverse, indicated by the kewyords ‘rel’ and ‘rev’. Most methods in the helper will take a $rel param, which must be either ‘rel’ or ‘rev’. Most methods also take a $type param, which is used for specifying the link type (e.g. alternate, start, next, prev, chapter, etc).

Relationships can be added to page objects manually, or found by traversing the container registered in the helper. The method findRelation($page, $rel, $type) will first try to find the given $rel of $type from the $page by calling $page->findRel($type) or $page->findRel($type). If the $page has a relation that can be converted to a page instance, that relation will be used. If the $page instance doesn’t have the specified $type, the helper will look for a method in the helper named search$rel$type (e.g. searchRelNext() or searchRevAlternate()). If such a method exists, it will be used for determining the $page’s relation by traversing the container.

Not all relations can be determined by traversing the container. These are the relations that will be found by searching:

• searchRelStart(), forward ‘start’ relation: the first page in the container.
• searchRelNext(), forward ‘next’ relation; finds the next page in the container, i.e. the page after the active page.
• searchRelPrev(), forward ‘prev’ relation; finds the previous page, i.e. the page before the active page.
• searchRelChapter(), forward ‘chapter’ relations; finds all pages on level 0 except the ‘start’ relation or the active page if it’s on level 0.
• searchRelSection(), forward ‘section’ relations; finds all child pages of the active page if the active page is on level 0 (a ‘chapter’).
• searchRelSubsection(), forward ‘subsection’ relations; finds all child pages of the active page if the active pages is on level 1 (a ‘section’).
• searchRevSection(), reverse ‘section’ relation; finds the parent of the active page if the active page is on level 1 (a ‘section’).
• searchRevSubsection(), reverse ‘subsection’ relation; finds the parent of the active page if the active page is on level 2 (a ‘subsection’).

Note

When looking for relations in the page instance ($page->getRel($type) or $page->getRev($type)), the helper accepts the values of type String, Array, Zend\Config, or Zend\Navigation\Page\AbstractPage. If a string is found, it will be converted to a Zend\Navigation\Page\Uri. If an array or a config is found, it will be converted to one or several page instances. If the first key of the array/config is numeric, it will be considered to contain several pages, and each element will be passed to the page factory. If the first key is not numeric, the array/config will be passed to the page factory directly, and a single page will be returned.

The helper also supports magic methods for finding relations. E.g. to find forward alternate relations, call $helper->findRelAlternate($page), and to find reverse section relations, call $helper->findRevSection($page). Those calls correspond to $helper->findRelation($page, ‘rel’, ‘alternate’); and $helper->findRelation($page, ‘rev’, ‘section’); respectively.

To customize which relations should be rendered, the helper uses a render flag. The render flag is an integer value, and will be used in a bitwise and (&) operation against the helper’s render constants to determine if the relation that belongs to the render constant should be rendered.

See the example below for more information.

• Zend\View\Helper\Navigation\Links::RENDER_ALTERNATE
• Zend\View\Helper\Navigation\Links::RENDER_STYLESHEET
• Zend\View\Helper\Navigation\Links::RENDER_START
• Zend\View\Helper\Navigation\Links::RENDER_NEXT
• Zend\View\Helper\Navigation\Links::RENDER_PREV
• Zend\View\Helper\Navigation\Links::RENDER_CONTENTS
• Zend\View\Helper\Navigation\Links::RENDER_INDEX
• Zend\View\Helper\Navigation\Links::RENDER_GLOSSARY
• Zend\View\Helper\Navigation\Links::RENDER_COPYRIGHT
• Zend\View\Helper\Navigation\Links::RENDER_CHAPTER
• Zend\View\Helper\Navigation\Links::RENDER_SECTION
• Zend\View\Helper\Navigation\Links::RENDER_SUBSECTION
• Zend\View\Helper\Navigation\Links::RENDER_APPENDIX
• Zend\View\Helper\Navigation\Links::RENDER_HELP
• Zend\View\Helper\Navigation\Links::RENDER_BOOKMARK
• Zend\View\Helper\Navigation\Links::RENDER_CUSTOM
• Zend\View\Helper\Navigation\Links::RENDER_ALL

The constants from RENDER_ALTERNATE to RENDER_BOOKMARK denote standard HTML link types. RENDER_CUSTOM denotes non-standard relations that specified in pages. RENDER_ALL denotes standard and non-standard relations.

Methods in the links helper:

• {get|set}RenderFlag() gets/sets the render flag. Default is RENDER_ALL. See examples below on how to set the render flag.
• findAllRelations() finds all relations of all types for a given page.
• findRelation() finds all relations of a given type from a given page.
• searchRel{Start|Next|Prev|Chapter|Section|Subsection}() traverses a container to find forward relations to the start page, the next page, the previous page, chapters, sections, and subsections.
• searchRev{Section|Subsection}() traverses a container to find reverse relations to sections or subsections.
• renderLink() renders a single link element.

Basic usage

Specify relations in pages

This example shows how to specify relations in pages.

$container = new Zend\Navigation\Navigation(array(
    array(
        'label' => 'Relations using strings',
        'rel'   => array(
            'alternate' => 'http://www.example.org/'
        ),
        'rev'   => array(
            'alternate' => 'http://www.example.net/'
        )
    ),
    array(
        'label' => 'Relations using arrays',
        'rel'   => array(
            'alternate' => array(
                'label' => 'Example.org',
                'uri'   => 'http://www.example.org/'
            )
        )
    ),
    array(
        'label' => 'Relations using configs',
        'rel'   => array(
            'alternate' => new Zend\Config\Config(array(
                'label' => 'Example.org',
                'uri'   => 'http://www.example.org/'
            ))
        )
    ),
    array(
        'label' => 'Relations using pages instance',
        'rel'   => array(
            'alternate' => Zend\Navigation\Page\AbstractPage::factory(array(
                'label' => 'Example.org',
                'uri'   => 'http://www.example.org/'
            ))
        )
    )
));

Default rendering of links

This example shows how to render a menu from a container registered/found in the view helper.

In a view script or layout:

<?php echo $this->view->navigation()->links(); ?>

Output:

<link rel="alternate" href="/products/server/faq/format/xml">
<link rel="start" href="/" title="Home">
<link rel="next" href="/products/server/editions" title="Editions">
<link rel="prev" href="/products/server" title="Foo Server">
<link rel="chapter" href="/products" title="Products">
<link rel="chapter" href="/company/about" title="Company">
<link rel="chapter" href="/community" title="Community">
<link rel="canonical" href="http://www.example.com/?page=server-faq">
<link rev="subsection" href="/products/server" title="Foo Server">

Specify which relations to render

This example shows how to specify which relations to find and render.

Render only start, next, and prev:

$helper->setRenderFlag(Zend\View\Helper\Navigation\Links::RENDER_START |
                       Zend\View\Helper\Navigation\Links::RENDER_NEXT |
                       Zend\View\Helper\Navigation\Links::RENDER_PREV);

Output:

<link rel="start" href="/" title="Home">
<link rel="next" href="/products/server/editions" title="Editions">
<link rel="prev" href="/products/server" title="Foo Server">

Render only native link types:

$helper->setRenderFlag(Zend\View\Helper\Navigation\Links::RENDER_ALL ^
                       Zend\View\Helper\Navigation\Links::RENDER_CUSTOM);

Output:

<link rel="alternate" href="/products/server/faq/format/xml">
<link rel="start" href="/" title="Home">
<link rel="next" href="/products/server/editions" title="Editions">
<link rel="prev" href="/products/server" title="Foo Server">
<link rel="chapter" href="/products" title="Products">
<link rel="chapter" href="/company/about" title="Company">
<link rel="chapter" href="/community" title="Community">
<link rev="subsection" href="/products/server" title="Foo Server">

Render all but chapter:

$helper->setRenderFlag(Zend\View\Helper\Navigation\Links::RENDER_ALL ^
                       Zend\View\Helper\Navigation\Links::RENDER_CHAPTER);

Output:

<link rel="alternate" href="/products/server/faq/format/xml">
<link rel="start" href="/" title="Home">
<link rel="next" href="/products/server/editions" title="Editions">
<link rel="prev" href="/products/server" title="Foo Server">
<link rel="canonical" href="http://www.example.com/?page=server-faq">
<link rev="subsection" href="/products/server" title="Foo Server">