The advanced Content Filter uses Symfony's Expression Language.
This help page includes a summary of [the Symfony's Expression Language documentation page.](https://symfony.com/doc/current/components/expression_language/syntax.html)
## Basics
The advanced content filter matches each post that is about to be displayed against each enabled rule you set.
A rule is a boolean expression that should return either `true` or `false` depending on post variables.
If the expression using a post variables returns `true`, the post will be collapsed and the matching rule name will be displayed above the collapsed content.
A post will be collapsed if at least one rule matches, but all matching rule names will be displayed above the collapsed content.
1. Collapse posts with specific domains `body matches "/\\.example\\.com/"`
2. Collapse posts that contains the words `body matches "/Guten Morgen/"`
3. Collapse posts with the word facebook that have a space in front and after the word `body matches "//s facebook/s /"`
4. Collapse posts that contains more than 1 image `body matches "/(?:(?:(?:\\[url(?:=.*)?\\])?\\[img(?:=.*)?\\].*\\[\\/img\\]\\s*(?:\\[\\/url\\])?)\\s*){2}/"`
Control characters (e.g. ``\n``) in expressions are replaced with whitespace. To avoid this, escape the sequence with a single backslash (e.g. ``\\n``).
[attachment type='link' url='https://www.eyeem.com/p/120800309' title='Over-compensation Street Night Car Lights Jeep No | EyeEm' image='https://cdn.eyeem.com/thumb/b2f019738cbeef06e2f8c9517c6286a8adcd3a00-1522184820641/640/480']Photo by @[url=https://twitter.com/MrPetovan]MrPetovan[/url][/attachment]</td>
Over-compensation #<a href="https://friendica.mrpetovan.com/search?tag=Street" class="tag" title="Street">Street</a> #<a href="https://friendica.mrpetovan.com/search?tag=Night" class="tag" title="Night">Night</a> #<a href="https://friendica.mrpetovan.com/search?tag=CarLights" class="tag" title="CarLights">CarLights</a> #<a href="https://friendica.mrpetovan.com/search?tag=Jeep" class="tag" title="Jeep">Jeep</a> #<a href="https://friendica.mrpetovan.com/search?tag=NoPeople" class="tag" title="NoPeople">NoPeople</a> #<a href="https://friendica.mrpetovan.com/search?tag=Close" class="tag" title="Close">Close</a>-up <div class="type-link"><a href="https://www.eyeem.com/p/120800309" target="_blank"><img src="https://friendica.mrpetovan.com/proxy/bb/aHR0cHM6Ly9jZG4uZXllZW0uY29tL3RodW1iL2IyZjAxOTczOGNiZWVmMDZlMmY4Yzk1MTdjNjI4NmE4YWRjZDNhMDAtMTUyMjE4NDgyMDY0MS82NDAvNDgw" alt="" title="Over-compensation Street Night Car Lights Jeep No | EyeEm" class="attachment-image"></a><br><h4><a href="https://www.eyeem.com/p/120800309">Over-compensation Street Night Car Lights Jeep No | EyeEm</a></h4><blockquote>Photo by @<a href="https://twitter.com/MrPetovan" class="userinfo mention" title="MrPetovan">MrPetovan</a></blockquote><sup><a href="https://www.eyeem.com/p/120800309">www.eyeem.com</a></sup></div>
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