Django default template tags

This example, besides being incorrect in some languages as noted above, would fail:. You would get an error when running django-admin compilemessages :. Sometimes words have several meanings, such as "May" in English, which refers to a month name and to a verb. To enable translators to translate these words correctly in different contexts, you can use the django. Both take a context string as the first variable. In the resulting. Contextual markers are also supported by the translate and blocktranslate template tags.

Use the lazy versions of translation functions in django. These functions store a lazy reference to the string — not the actual translation.

The translation itself will be done when the string is used in a string context, such as in template rendering. This is essential when calls to these functions are located in code paths that are executed at module load time.

This is something that can easily happen when defining models, forms and model forms, because Django implements these such that their fields are actually class-level attributes.

For that reason, make sure to use lazy translations in the following cases:. For example, to translate the help text of the name field in the following model, do the following:. For model methods, you can provide translations to Django and the admin site with the description argument to the display decorator:. This necessitates the use of the helper function described next.

Therefore, you are authorized to pass a key name instead of an integer as the number argument. Then number will be looked up in the dictionary under that key during string interpolation. If the string contains exactly one unnamed placeholder, you can interpolate directly with the number argument:. Instead, you can use django. For example:.

In this case, the lazy translations in result will only be converted to strings when result itself is used in a string usually at template rendering time. For any other case where you would like to delay the translation, but have to pass the translatable string as argument to another function, you can wrap this function inside a lazy call yourself. The bidi attribute is True only for bi-directional languages. The source of the language information is the django. Similar access to this information is available for template code.

See below. Translations in Django templates uses two template tags and a slightly different syntax than in Python code. As with all template tags, this tag needs to be loaded in all templates which use translations, even those templates that extend from other templates which have already loaded the i18n tag. Translated strings will not be escaped when rendered in a template. This allows you to include HTML in translations, for example for emphasis, but potentially dangerous characters e.

If the noop option is present, variable lookup still takes place but the translation is skipped. Internally, inline translations use an gettext call. In case a template var myvar above is passed to the tag, the tag will first resolve such variable to a string at run-time and then look up that string in the message catalogs. Contrarily to the translate tag, the blocktranslate tag allows you to mark complex sentences consisting of literals and variable content for translation by making use of placeholders:.

To translate a template expression — say, accessing object attributes or using template filters — you need to bind the expression to a local variable for use within the translation block. You can use multiple expressions inside a single blocktranslate tag:. When you use both the pluralization feature and bind values to local variables in addition to the counter value, keep in mind that the blocktranslate construct is internally converted to an ngettext call.

This means the same notes regarding ngettext variables apply. Reverse URL lookups cannot be carried out within the blocktranslate and should be retrieved and stored beforehand:. Second paragraph. In this example, the translation infrastructure will be passed the string "yes,no" , not the individual strings "yes" and "no".

The translated string will need to contain the comma so that the filter parsing code knows how to split up the arguments.

For example, a German translator might translate the string "yes,no" as "ja,nein" keeping the comma intact. Just like with Python code , these notes for translators can be specified using comments, either with the comment tag:. Just for completeness, these are the corresponding fragments of the resulting.

If you want to select a language within a template, you can use the language template tag:. Example: en-us. See How Django discovers language preference. Hebrew, Arabic. English, French, German, etc. If you enable the django. You can also retrieve information about any of the available languages using provided template tags and filters. If you do this in your view:.

Django provides an integrated solution for these problems: It passes the translations into JavaScript, so you can call gettext , etc. The main solution to these problems is the following JavaScriptCatalog view, which generates a JavaScript code library with functions that mimic the gettext interface, plus an array of translation strings.

A view that produces a JavaScript code library with functions that mimic the gettext interface, plus an array of translation strings. Translation domain containing strings to add in the view output. Defaults to 'djangojs'. A list of application names among installed applications. Those apps should contain a locale directory. The precedence of translations is such that the packages appearing later in the packages argument have higher precedence than the ones appearing at the beginning.

This is important in the case of clashing translations for the same literal. If you use more than one JavaScriptCatalog view on a site and some of them define the same strings, the strings in the catalog that was loaded last take precedence. When the catalog is loaded, your JavaScript code can use the following methods:. The gettext function behaves similarly to the standard gettext interface within your Python code:.

The ngettext function provides an interface to pluralize words and phrases:. The interpolate function supports dynamically populating a format string. The interpolation syntax is borrowed from Python, so the interpolate function supports both positional and named interpolation:.

Positional interpolation: obj contains a JavaScript Array object whose elements values are then sequentially interpolated in their corresponding fmt placeholders in the same order they appear. Named interpolation: This mode is selected by passing the optional boolean named parameter as true. This emulates the gettext function but does nothing, returning whatever is passed to it:.

The pgettext function behaves like the Python variant pgettext , providing a contextually translated word:. The npgettext function also behaves like the Python variant npgettext , providing a pluralized contextually translated word:.

The pluralidx function works in a similar way to the pluralize template filter, determining if a given count should use a plural form of a word or not:. In the simplest case, if no custom pluralization is needed, this returns false for the integer 1 and true for all other numbers. However, pluralization is not this simple in all languages. If the language does not support pluralization, an empty value is provided. Additionally, if there are complex rules around pluralization, the catalog view will render a conditional expression.

This will evaluate to either a true should pluralize or false should not pluralize value. In order to use another client-side library to handle translations, you may want to take advantage of the JSONCatalog view. See the documentation for JavaScriptCatalog to learn about possible values and use of the domain and packages attributes.

Server-side caching will reduce CPU load. To circumvent this "feature", forms. CharField is never returning None, cause it's better to store empty strings DB… yeah, sure :P — sorry for the bragging, I couldn't help myself. WooYek: Another point is taking logic out of the template. Simply, if you have those tags scattered all over your template, I'd say it's more your failure than Django's.

I'm just saying: Its — the missing setting — not there because there was no much demand, due to not many places — in django — that "empty" means None type. There's nothing more to it. Anyway this is not the please, for such discussion. Again, sorry about the brag, for me it's EOT. Janusz Skonieczny Janusz Skonieczny 15k 9 9 gold badges 49 49 silver badges 60 60 bronze badges.

This actually does the job, I placed the code in a middleware file, but outside of the class — Peter. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

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In this tutorial, we will look at how to create custom template tags and filters in Django. Prerequisites To follow along, you must have: The ability to create a simple Django application.

Python and Django installed. Goal By the end of this tutorial, you will be able to: Understand the use of custom template tags and filters and how they work. Create your customized template tags and filters to suit your needs. Getting started Your custom tags and filters must be within a Django app. Follow the following steps to create the files needed for this tutorial.

Inside your app, create a directory called templatetags at the same level as the views, models, etc. Your app structure will now look something similar to this:. Library An upper function that capitalizes word passed to it. We then register the filter using a suitable name.