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Selects an argument depending on a condition.<\/p>\n

For example:<\/p>\n

{{ value|if:"yes":"no" }}\n<\/code><\/pre>\n
This is a shortcut for using the tag#if<\/code><\/a> tag. The same can be expressed as follows:<\/p>\n
{% if value %}yes{% else %}no{% endif %}\n<\/code><\/pre>\n
Note that falsy values (0, false<\/code>, undefined<\/code> or empty string) evaluate to false.<\/p>\n
In templates, the compiler evaluates the condition once and only evaluates the\nselected argument. The other argument is not evaluated, so a model lookup in\nthat branch does not run. Both arguments are required; use undefined<\/code> when the\nfalse branch should produce no value.<\/p>\n
Combine the filter with as<\/code> to reuse the selected value:<\/p>\n
{% if show_image|if:m.media[id]:undefined as medium %}\n    {{ medium.mime|escape }}\n{% endif %}\n<\/code><\/pre>\n
The media model is only queried when show_image<\/code> is true. The block is rendered\nwhen the selected value is truthy, and medium<\/code> contains that value.<\/p>\n
This lazy evaluation applies to compiled templates. Direct Erlang calls to\nfilter_if:'if'\/4<\/code> follow normal Erlang evaluation: all arguments are evaluated\nbefore the function is called.<\/p>\n
Elaborate examples<\/h2>\n
{% with is_i18n|if:r.translation[lang_code].body:r.body as body %}\n<\/code><\/pre>\n
So if is_i18n<\/code> evaluates to true, body<\/code> is assigned to r.translation[lang_code].body<\/code>, else to r.body<\/code>.<\/p>\n
{% include "_language_attrs.tpl" id=pid class=(pid==id)|if:"active":"" %}\n<\/code><\/pre>\n
Add parameter class<\/code> to the included template; when pid<\/code> equals id<\/code>, class<\/code> is "active"<\/code>, otherwise an empty string.<\/p>","slug":"if","is_protected":false,"visible_for":0,"tz":"UTC","language":["en"],"doc_source_hash":"5e66b1e866ad2b99ff087db1041a82beba3a530550cb3b2b0afa745eec351329","is_featured":false,"content_group_id":{"id":2551,"is_a":["meta","content_group"],"name":"content_group_imported_docs","title":"Imported documentation","uri":"https:\/\/zotonic.com\/id\/content_group_imported_docs"},"category_id":{"id":325,"is_a":["meta","category"],"name":"template_filter","title":"Filters","uri":"https:\/\/test.zotonic.com\/id\/325"},"doc_source_path":"apps\/zotonic_mod_base\/src\/filters\/filter_if.erl","publication_start":"2023-06-24T08:18:02Z","github_url":"https:\/\/github.com\/zotonic\/zotonic\/blob\/master\/apps\/zotonic_mod_base\/src\/filters\/filter_if.erl","pivot_location_lng":null,"doc_source_kind":"filter","name":"doc_template_filter_filter_if","is_unfindable":false,"is_published":true,"pivot_geocode":null,"created":"2020-05-30T05:47:39Z","uri":null,"doc_status":"current","is_dependent":false,"erlang_app":"zotonic_mod_base","publication_end":"9999-06-01T00:00:00Z","modifier_id":{"id":1,"is_a":["person"],"name":"administrator","title":"Site Administrator","uri":"https:\/\/zotonic.com\/id\/1"},"privacy":0,"doc_source_commit":"7df977519c8cf191b758d30a0ddca1826a013903\n","erlang_module":"filter_if","creator_id":{"id":336,"is_a":["person","robot"],"name":"gitbot","title":"Git","uri":"https:\/\/zotonic.com\/id\/336"},"modified":"2026-10-22T13:33:27Z","title_slug":"if"},"uri":"https:\/\/zotonic.com\/id\/1849","uri_template":"https:\/\/zotonic.com\/id\/:id","websub":{"hub":"https:\/\/zotonic.com\/.zotonic\/websub","topic":"https:\/\/zotonic.com\/.zotonic\/websub\/topic\/1849"}},"status":"ok"}