About multi-language and language-alternate fields

ProcessWire supports the use of multi-language fields and language-alternate fields. A multi-language field is a single field that supports multiple languages, and these are typically text-based fields. Language-alternate fields are separate fields where the value of one can substitute for another, when the user's language justifies it. Below is a short video that demonstrates the use of both.

How to install

To use multi-language fields or language-alternate fields, you must first install the "Language Support - Fields" module, included with ProcessWire 2.2 or newer. To do this, click "install" for "Language Support - Fields" from the Modules menu.

When and where to use language fields

Language fields (whether multi-language or language-alternate) enable your site's template files to deal with just one field name while the value is affected by the current user's language. In fact, your template files don't even need to know about languages. This makes it a relatively simple matter to support languages in existing sites. However, one should also consider other approaches such as using a separate structure (tree) of pages for each language, or using a module like Oliver's ProcessLanguages.

In order to present your site's content in a different language using language fields, the current user's language has to be set to the one you want the site to display in. This is a simple matter if you are dealing with users that can log-in, because they can set their language from their profile. However, we are assuming you want to use language fields for the purpose of having multi-language versions of your site available to anonymous visitors. There are a large number of approaches you could take. See these examples of how multi-language fields can be used to produce a multi-language website.

Multi-language fields

ProcessWire 2.2 includes 3 new fieldtypes that support multiple languages:

  • TextLanguage – single line text field
  • TextareaLanguage – multi-line text or rich-text (TinyMCE) field
  • PageTitleLanguage – special text field to be used with page titles only

These 3 fieldtypes correspond to the standard text fieldtypes already included in ProcessWire: Text, Textarea and PageTitle. When you convert a field to the multi-language version (i.e. convert a Textarea to a TextareaLanguage) the field now has inputs for every installed language in your system. If an input is left blank for any language, then the default language is substituted at runtime. 

Converting an existing field to multi-language

To convert an existing field to a multi-language field, it must be a Text, Textarea or PageTitle field. Edit the field settings in Setup > Fields > Your Field. Change the "Type" to be: TextLanguage, TextareaLanguage or PageTitleLanguage. Because this change involves adding new columns to the field's database table, it will ask you to confirm the schema change. While this is a safe process, any time something modifies existing database tables, it's a good idea to make sure you have a backup of your database. When ready, confirm the change, and your field will now support all languages installed in the system. Should you want to convert back, repeat the same process but choose the non multi-language fieldtype instead. 

Please note: when converting to or from a multi-language field, some of your field settings can be lost. For instance, if you are converting a textarea field that uses TinyMCE for input, you will have to reconfigure these settings after converting to or from a multi-language field.

Creating a new multi-language field

To create a new multi-language field, all you need to do is go to Setup > Fields > Add New. When it asks you to select a field type, choose either TextLanguage or TextareaLanguage.

Language-alternate fields

Language-alternate fields allow for the value of one field to replace the value of another when the user's language is something other than the default. Unlike multi-language fields, language-alternate fields are actually separate fields that you create on your own. ProcessWire identifies them based on the name you give them. The name is a combination of an existing field in the system combined with the language name.

Creating a language-alternate field

If you wanted a Dutch version of your "body" field, you would name your new field "body_dutch". Meaning, a language alternate field should be named with the original field name, followed by an underscore and the language name.

Assuming you have a language installed named "dutch" and the current user's language is Dutch, then ProcessWire will return $page->body_dutch when you access $page->body. However, if $page->body_dutch is empty, then it will return $page->body instead.

Unlike multi-language fields, language alternate fields can be used with any type of field.

How language fields work from the $pages API

Whether using multi-language fields or language-alternate fields, when a user's language is something other than the default, then the value of the field reflects the language-specific value, if it is available. If it is not available, then the default language version is substituted. Likewise, any API calls using selectors that include the field, will match pages that contain the term in either the current user's language, OR the default language. 

Example

We will assume that the current user's language is Dutch and that this is a language installed in the system. We will also assume that the field "body" is a multi-language textarea field. Because the user's current language is Dutch, the following API call matches any pages that contain the phrase "welkom vrienden" (welcome friends) in the Dutch body field OR the default body field. If there are other languages installed, it does not attempt to search them.

$results = $pages->find("body*=welkom vrienden"); 

Lets now change the example and say that "body" was not a multi-language field, but it had a language-alternate field called "body_dutch". Because the user's current language is Dutch, the results of the above API call would be identical to when we were considering multi-language fields. Meaning, a search in the "body" field actually performs a search on "body_dutch" and "body" at the same time. Should you need to, you can also target just the language-alternate field by specifying it's name in the selector, i.e. "body_dutch" rather than "body".

Getting and setting language values in the API

Getting values is no different from anywhere else in the API except that you'll be getting a value that is specific to the current user's language. As a result, if you wanted to get a value in some other language installed on your system, you would have to switch the current user's language:

$language = $user->language; // save the user's language
$user->language = $languages->get("french"); // change user to French
echo $page->body; // output the French version of body
$user->language = $language; // restore the user's language

The value of a multi-language or language-alternate field is affected by the "outputFormatting" setting of a page. On the front-end of your site, outputFormatting is always turned on, unless you've turned it off. In other applications, like in the admin, or at the command line, outputFormatting may be off by default. The example above, and most of the documentation on this page assumes that outputFormatting is on. In cases where outputFormatting is off, the value of our language fields may be different. These differences are outlined below:

Multi-language field values

When outputFormatting is ON, the value of a multi-language field is a string (as it shows in most examples on this page). That string reflects the value from the current user's language.  If the value is blank in the current user's language, the value from the default language will be there instead.

However, when outputFormatting is OFF, the value of a multi-language field (like $page->body) will instead return an object of type LanguagesPageFieldValue, rather than a string. That object contains all of the translations available for the given field.  If you access or typecast this object as a string, it will return the same thing as if outputFormatting was on. If you want to get or set the value of this field for another language, you can do the following:

$page->of(false); // turn off outputFormatting (if it's not already)
$dutch = $languages->get('dutch'); // get the language we want
$body = $page->body->getLanguageValue($dutch); // get the unformatted value in Dutch

This is very similar to what we did in an earlier example, except that we didn't have to change the current user's language, and we're dealing with a value that has not had any textformatters applied to it (which is exactly what you want if you need to modify and save it).

Setting a multi-language field value

When you set the value of a multi-language field, it sets the value for the current user's language. So if the current user's language was Dutch, and we set the value of "body", it would set it for the Dutch version of body:

$page->body = "welkom vrienden"; // sets it in Dutch

If we change the user's language, and then set it again, it sets it in that user's language:

$user->language = $languages->get("spanish"); 
$page->body = "Bienvenidos amigos"; // sets it in Spanish

You can also set the language-specific values without changing the current user's language by using the setLanguageValue() function. This is usually preferable when modifying the contents of multiple languages:

$dutch = $languages->get("dutch"); // retrieve Dutch
$spanish = $languages->get("spanish"); // retrive Spanish
$page->of(false); // outputFormatting must be OFF
$page->body->setLanguageValue($dutch, "Welkom vrienden"); // set in Dutch
$page->body->setLanguageValue($spanish, "Bienvenidos amigos"); // set in Spanish
$page->save(); // save the page with the new language values

Language-alternate field values

For the following description, lets assume we have a field called "body" and another called "body_dutch", which is the Dutch alternate for body. The value of a language-alternate field is always a string, regardless of whether outputFormatting is on or off. But when outputFormatting is ON (as it is in most API usage), the value of "body" will be the value of the alternate field when the user's language justifies it. For instance, if the user's language is Dutch, and the value of $page->body_dutch is populated, then an access to $page->body will actually return the value from $page->body_dutch. But if $page->body_dutch is not populated, then the default, $page->body is returned.

When outputFormatting is OFF, the language-alternate fields behave as if they were completely separate, unrelated fields. Meaning, $page->body will always return the value of $page->body (never substituting the value of $page->body_dutch).

Regardless of whether outputFormatting is on or off, you can always access the language-specific alternate fields and expect that they will return the value in the language they signify. So regardless of what the current user's language is, $page->body_dutch will always return the Dutch version of body, and $page->body_spanish will always return the Spanish version. It is only $page->body that has it's value substituted with alternate language versions when outputFormatting is on.  

Setting a language-alternate field value

Whenever you set a language-alternate field value, languages are not a consideration–the fields perform exactly the same as if language support wasn't active. So if you set $page->body, it is always going to set it for the default language. If you set $page->body_dutch, it is always going to set it for Dutch. As a result, the behavior in this aspect is the same regardless of whether outputFormatting is on or off. But you would typically only set values to a page with outputFormatting OFF (assuming you were going to save it), so this distinction may not matter much in actual use. Given that, an example may be redundant, but here is one anyway:

$page->of(false); // turn off outputFormatting
$page->body = "Welcome friends"; // sets it in default language
$page->body_dutch = "Welkom vrienden"; // sets it in Dutch
$page->body_spanish = "Bienvenidos amigos"; // sets it in Spanish
$page->save(); // save the page

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