Symfony
sponsored by SensioLabs
Menu
  • About
  • Documentation
  • Screencasts
  • Cloud
  • Certification
  • Community
  • Businesses
  • News
  • Download
  1. Home
  2. Documentation
  3. Components
  4. The CssSelector Component
  • Documentation
  • Book
  • Reference
  • Bundles
  • Cloud
Search by Algolia

Table of Contents

  • Installation
  • Usage
    • Why use CSS selectors?
    • The CssSelector component
    • Limitations of the CssSelector component

The CssSelector Component

Edit this page

Warning: You are browsing the documentation for Symfony 2.0, which is no longer maintained.

Read the updated version of this page for Symfony 6.2 (the current stable version).

The CssSelector Component

The CssSelector Component converts CSS selectors to XPath expressions.

Installation

You can install the component in several different ways:

  • Use the official Git repository (https://github.com/symfony/CssSelector);
  • Install it via Composer (symfony/css-selector on Packagist).

Usage

Why use CSS selectors?

When you're parsing an HTML or an XML document, by far the most powerful method is XPath.

XPath expressions are incredibly flexible, so there is almost always an XPath expression that will find the element you need. Unfortunately, they can also become very complicated, and the learning curve is steep. Even common operations (such as finding an element with a particular class) can require long and unwieldy expressions.

Many developers -- particularly web developers -- are more comfortable using CSS selectors to find elements. As well as working in stylesheets, CSS selectors are used in Javascript with the querySelectorAll function and in popular Javascript libraries such as jQuery, Prototype and MooTools.

CSS selectors are less powerful than XPath, but far easier to write, read and understand. Since they are less powerful, almost all CSS selectors can be converted to an XPath equivalent. This XPath expression can then be used with other functions and classes that use XPath to find elements in a document.

The CssSelector component

The component's only goal is to convert CSS selectors to their XPath equivalents:

1
2
3
use Symfony\Component\CssSelector\CssSelector;

print CssSelector::toXPath('div.item > h4 > a');

This gives the following output:

1
descendant-or-self::div[contains(concat(' ',normalize-space(@class), ' '), ' item ')]/h4/a

You can use this expression with, for instance, DOMXPath or SimpleXMLElement to find elements in a document.

Tip

The Crawler::filter() method uses the CssSelector component to find elements based on a CSS selector string. See the The DomCrawler Component for more details.

Limitations of the CssSelector component

Not all CSS selectors can be converted to XPath equivalents.

There are several CSS selectors that only make sense in the context of a web-browser.

  • link-state selectors: :link, :visited, :target
  • selectors based on user action: :hover, :focus, :active
  • UI-state selectors: :enabled, :disabled, :indeterminate (however, :checked and :unchecked are available)

Pseudo-elements (:before, :after, :first-line, :first-letter) are not supported because they select portions of text rather than elements.

Several pseudo-classes are not yet supported:

  • :lang(language)
  • root
  • *:first-of-type, *:last-of-type, *:nth-of-type, *:nth-last-of-type, *:only-of-type. (These work with an element name (e.g. li:first-of-type) but not with *.
This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.
We stand with Ukraine.
Version:
Check Code Performance in Dev, Test, Staging & Production

Check Code Performance in Dev, Test, Staging & Production

Peruse our complete Symfony & PHP solutions catalog for your web development needs.

Peruse our complete Symfony & PHP solutions catalog for your web development needs.

↓ Our footer now uses the colors of the Ukrainian flag because Symfony stands with the people of Ukraine.

Avatar of Maxime Aknin, a Symfony contributor

Thanks Maxime Aknin (@3m1x4m) for being a Symfony contributor

2 commits • 6 lines changed

View all contributors that help us make Symfony

Become a Symfony contributor

Be an active part of the community and contribute ideas, code and bug fixes. Both experts and newcomers are welcome.

Learn how to contribute

Symfony™ is a trademark of Symfony SAS. All rights reserved.

  • What is Symfony?
    • Symfony at a Glance
    • Symfony Components
    • Case Studies
    • Symfony Releases
    • Security Policy
    • Logo & Screenshots
    • Trademark & Licenses
    • symfony1 Legacy
  • Learn Symfony
    • Symfony Docs
    • Symfony Book
    • Reference
    • Bundles
    • Best Practices
    • Training
    • eLearning Platform
    • Certification
  • Screencasts
    • Learn Symfony
    • Learn PHP
    • Learn JavaScript
    • Learn Drupal
    • Learn RESTful APIs
  • Community
    • SymfonyConnect
    • Support
    • How to be Involved
    • Code of Conduct
    • Events & Meetups
    • Projects using Symfony
    • Downloads Stats
    • Contributors
    • Backers
  • Blog
    • Events & Meetups
    • A week of symfony
    • Case studies
    • Cloud
    • Community
    • Conferences
    • Diversity
    • Documentation
    • Living on the edge
    • Releases
    • Security Advisories
    • SymfonyInsight
    • Twig
    • SensioLabs
  • Services
    • SensioLabs services
    • Train developers
    • Manage your project quality
    • Improve your project performance
    • Host Symfony projects
    Deployed on
Follow Symfony
Search by Algolia