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Tutorial for using xliffmerge with angular cli

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Martin Roob edited this page Jul 9, 2018 · 25 revisions

(Updated to Angular 6)

This tutorial shows in a few step, how to use xliffmerge in an Angular App, which is generated with angular-cli.

It shows the basic workflow for preparing an application for translation, translating it, running it, changing it, translating it again, running it again...

Start a new project

If you haven't done it at all, install angular-cli globally:

npm install -g @angular/cli

Then you can create a new project:

ng new sampleapp

cd sampleapp

npm install ngx-i18nsupport

(The last step adds the tooling to your project, you can install it globally if yout want (npm install -g ngx-i18nsupport)

Prepare the app for translations

For this tutorial we assume, that your preferred language is not English, but something else, e.g. German. So you want to write your application in German and translate it to English later. This is not a hard requirement, of course you can use English as the default. I just decided to do it this way, because it is the way I do it.

So as a first step we change our application to German and additionally mark all text, that needs translation, with an i18n-Attribute. For details have a look at the Angular Cookbook about Internationalization.

Our src/app/app.component.html (generated by the cli) now looks like this:

<div style="text-align:center">
  <h1 i18n>
    Willkomen zu {{ title }}!
  </h1>
  <img ..>
</div>
<h2 i18n>Hier einige Links, die den Anfang erleichtern: </h2>

Try running it (ng serve or npm run start, then open http:\\localhost:4200 in a browser), fix the test cases, if you want (they test for 'app works!' and will fail after the change).

It looks like

Willkomen zu app


Hier einige Links, die den Anfang erleichtern:

Generate a messages.xlf file

After the initial changes are made, the application now contains some i18n marked stuff and so you can extract this stuff for translation.

angular-cli has a task for this. So you can just type

ng xi18n --output-path i18n --i18n-locale de

Instead of typing, it is better to add a script to your package.json, that does it for you. Then you don't have to remember the command to type. So just add the following to your package.json scripts section:

{
  [...]
  "scripts": {
    [...]
    "extract-i18n": "ng xi18n --output-path i18n --i18n-locale de"
  }
  [...]
}

Then you can type

npm run extract-i18n

Some words about the parameters used in the command.

--output-path spefifies the path (relativ to src), where the generated file will be saved. We prefer to have it under src/i18n.

--i18n-locale specifies the language, that is used in the templates (the default language). It is supported starting with Angular 4. In prior versions it is ignored and the generator always assumes your templates are written in English.

After running the command you will find a newly generated file src/i18n/messages.xlf. If you open it with a text editor, you will see, that it is an XML file containing

...
      <trans-unit id="91fcc40bc784cacec7c70d5f1eee77ebc1d8d308" datatype="html">
        <source>
    Willkomen zu <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">3</context>
        </context-group>
      </trans-unit>
      <trans-unit id="1bd7be430ac3f26a91a30d76868397fa8fea9882" datatype="html">
        <source>Hier einige Links, die den Anfang erleichtern: </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">8</context>
        </context-group>
      </trans-unit>
...

In the next step you have to

  • create a copy of this file for every language you want to support.
  • translate it.

This is where xliffmerge comes into play.

Generate language specific files

Change the script you added in the last section to your package.json (add the stuff && xliffmerge...):

{
  [...]
  "scripts": {
    [...]
    "extract-i18n": "ng xi18n --output-path i18n --i18n-locale de && xliffmerge --profile xliffmerge.json de en"
  }
  [...]
}

xliffmerge.json is a small configuration file. Create it with the following content to tell xliffmerge where the files are located. (Details about the configuration options are contained in the usage section at the home page).

{
  "xliffmergeOptions": {
    "srcDir": "src/i18n",
    "genDir": "src/i18n"
  }
}

Now run the extraction process once again:

npm run extract-i18n

It will output some warnings:

WARNING: please translate file "src/i18n/messages.en.xlf" to target-language="en

THe warning tells you that you have to translate the English file.

You will now find 3 files under src/i18n

  1. messages.xlf the master file containing all the messages found in your app.

  2. messages.de.xlf the German version.

  3. messages.en.xlf the (up to now untranslated) English version.

If you open the files with a text editor, you will see

  • messages.xlf is the file Angular created for you. There are no <target> elements (no translation), the attribute source-language="de" tells the source language.
<?xml version="1.0" encoding="UTF-8" ?>
<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
  <file source-language="de" datatype="plaintext" original="ng2.template">
    <body>
...
      <trans-unit id="1bd7be430ac3f26a91a30d76868397fa8fea9882" datatype="html">
        <source>Hier einige Links, die den Anfang erleichtern: </source>
...
  • messages.de.xlf contains a copy, but there are <target> elements that contain the same values as the source elements. There is an additional attribute state="final".
<?xml version="1.0" encoding="UTF-8" ?>
<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
  <file source-language="de" datatype="plaintext" original="ng2.template" target-language="de">
    <body>
      <trans-unit id="91fcc40bc784cacec7c70d5f1eee77ebc1d8d308" datatype="html">
        <source>
    Willkomen zu <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">3</context>
        </context-group>
      <target state="final">
    Willkomen zu <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </target></trans-unit>
      <trans-unit id="1bd7be430ac3f26a91a30d76868397fa8fea9882" datatype="html">
        <source>Hier einige Links, die den Anfang erleichtern: </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">8</context>
        </context-group>
      <target state="final">Hier einige Links, die den Anfang erleichtern: </target></trans-unit>
    </body>
  </file>
</xliff>
  • messages.en.xlf is nearly the same, but the target-language is set to en and all <target> elements have an attribute state="new". This marks the fact that you have to translate it by your own.
<?xml version="1.0" encoding="UTF-8" ?>
<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
  <file source-language="de" datatype="plaintext" original="ng2.template" target-language="en">
    <body>
      <trans-unit id="91fcc40bc784cacec7c70d5f1eee77ebc1d8d308" datatype="html">
        <source>
    Willkomen zu <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">3</context>
        </context-group>
      <target state="new">
    Willkomen zu <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </target></trans-unit>
      <trans-unit id="1bd7be430ac3f26a91a30d76868397fa8fea9882" datatype="html">
        <source>Hier einige Links, die den Anfang erleichtern: </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">8</context>
        </context-group>
      <target state="new">Hier einige Links, die den Anfang erleichtern: </target></trans-unit>
    </body>
  </file>
</xliff>

Translate your messages files

Next you have to translate messages.en.xlf by yourself. Use a translation tool, if you want. E.g. have a look at Tiny Translator. At the end you just replace the target elements with the translated version and you change the state attribute to state="translated".

<?xml version="1.0" encoding="UTF-8" ?>
<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
  <file source-language="de" datatype="plaintext" original="ng2.template" target-language="en">
    <body>
      <trans-unit id="91fcc40bc784cacec7c70d5f1eee77ebc1d8d308" datatype="html">
        <source>
    Willkomen zu <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">3</context>
        </context-group>
      <target state="translated">
    Welcome to <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </target></trans-unit>
      <trans-unit id="1bd7be430ac3f26a91a30d76868397fa8fea9882" datatype="html">
        <source>Hier einige Links, die den Anfang erleichtern: </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">8</context>
        </context-group>
      <target state="translated">Here are some links to start with: </target></trans-unit>
    </body>
  </file>
</xliff>

Do not forget to put the translated files under configuration management, they should all be considered as source files.

Run your English version of the app

Add the following script to your package.json

{
  [...]
  "scripts": {
    [...]
    "extract-i18n": ...,
    "start-en": "ng serve --aot --i18n-file=src/i18n/messages.en.xlf --locale=en --i18n-format=xlf"
  }
  [...]
}

Run

npm run start-en

You now will see the English version of your app:

Welcome to app


Here are some links to start with

Congratulations!

Change your app and do it again

In the next steps you want to add new features to your app and that includes adding some new messages.

For example change src/app/app.component.html to

...
<div style="text-align:center">
  <h1 i18n>
    Willkomen zu {{ title }}!
  </h1>
  <img ..>
</div>
<h2 i18n>Hier einige Links, die den Anfang erleichtern: </h2>
<p i18n="Beschreibung der Anwendung">Diese Anwendung ist eine reine Demonstration und hat keine wirklich nutzbare Funktion.</p>
...

We just added another paragraph. And we used a description value for the i18n attribute.

Now extract the messages.xlf once again:

npm run extract-i18n

There will be some warnings again:

WARNING: merged 1 trans-units from master to "de"
WARNING: merged 1 trans-units from master to "en"
WARNING: please translate file "src/i18n/messages.en.xlf" to target-language="en

The warnings show you that there are new messages merged in (only 1 here).

Have a look at the newly generated xlf files (if they are under version control, you can directly look at the changes done), especially the English one:

<?xml version="1.0" encoding="UTF-8" ?>
<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
  <file source-language="de" datatype="plaintext" original="ng2.template" target-language="en">
    <body>
   <trans-unit id="91fcc40bc784cacec7c70d5f1eee77ebc1d8d308" datatype="html">
        <source>
    Willkomen zu <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">3</context>
        </context-group>
      <target state="translated">
    Welcome to <x id="INTERPOLATION" equiv-text="{{ title }}"/>!
  </target></trans-unit>
      <trans-unit id="1bd7be430ac3f26a91a30d76868397fa8fea9882" datatype="html">
        <source>Hier einige Links, die den Anfang erleichtern: </source>
        <context-group purpose="location">
          <context context-type="sourcefile">app/app.component.ts</context>
          <context context-type="linenumber">8</context>
        </context-group>
      <target state="translated">Here are some links to start with: </target></trans-unit>
    <trans-unit id="fb74bbbdf6190dc80f48622910221fd07ae0c70d" datatype="html">
        <source>Diese Anwendung ist eine reine Demonstration und hat keine wirklich nutzbare Funktion.</source>
        <target state="new">Diese Anwendung ist eine reine Demonstration und hat keine wirklich nutzbare Funktion.</target>
        <note priority="1" from="description">Beschreibung der Anwendung</note>
      </trans-unit></body>
  </file>
</xliff>

You see

  • the old parts are just there. The already done parts of the translation are untouched.
  • the new parts contain the German original as translation value and are marked with state="new"
  • the description attribute is contained as a <note> element. Translation tools will show it to support the translator.

In the next step you can send the file to your translator to do the work with the new parts (or you can do that by your own). If this should take some time, you can just run the application with the partly translated file, which is better than no version at all.

This is the incompletely translated versions output:

Welcome to app


Here are some links to start with


Diese Anwendung ist eine reine Demonstration und hat keine wirklich nutzbare Funktion.

After the translation is done, just run the new version.

npm run start-en

OK, you got it:

Welcome to app


Here are some links to start with


This application is just for demonstration purposes. It really has no value.
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