ngx-translate-messageformat-compiler

ngx-translate-messageformat-compiler

Compiler for ngx-translate that uses messageformat.js to compile translations using ICU syntax for handling pluralization and gender

• Installation
• Setup
• Usage
• About

Installation

This assumes that you've already installed ngx-translate.

Using npm:

npm install ngx-translate-messageformat-compiler messageformat --save

... or if you use yarn:

yarn add ngx-translate-messageformat-compiler messageformat

Setup

Changed dependencies for v4: You need to use Angular v6 and ngx-translate v10 for this version. Intl is expected to be present by the new messageformat version so the corresponding config option has been dropped. See CHANGELOG for more details.

Changed dependencies for v3: You need to use Angular v4/v5 and ngx-translate v8/v9 for this version. See CHANGELOG for more details.

Changed setup for v2: You no longer need to provide a MessageFormat instance. The compiler will do this. You still need to have messageformat installed, of course. See CHANGELOG for more details.

You need to configure TranslateModule so it uses TranslateMessageFormatCompiler as the compiler:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { TranslateCompiler, TranslateModule } from '@ngx-translate/core';
import { TranslateMessageFormatCompiler } from 'ngx-translate-messageformat-compiler';

import { AppComponent } from "./app";

@NgModule({
  imports: [
    BrowserModule,
    TranslateModule.forRoot({
      compiler: {
        provide: TranslateCompiler,
        useClass: TranslateMessageFormatCompiler
      }
    })
  ],
  bootstrap: [AppComponent]
})
export class AppModule {}

MessageFormat instances provide some methods to influence its behaviour, among them setBiDiSupport, and setStrictNumberSign. Learn about their meaning here: https://messageformat.github.io/messageformat/MessageFormat

You can override the values used when configuring MessageFormat by providing a configuration object for the MESSAGE_FORMAT_CONFIG injection token. Here's the default:

{
  biDiSupport: false,
  strictNumberSign: false
}

This is how you would enable bi-directional support, for example:

import { MESSAGE_FORMAT_CONFIG } from 'ngx-translate-messageformat-compiler';

@NgModule({
  // ...
  providers: [
    { provide: MESSAGE_FORMAT_CONFIG, useValue: { biDiSupport: true }}
  ]

})
}

Usage

This library implements neither the syntax used for pluralization (et al) nor the "mechanics" for making translations work in your Angular app. The former is MessageFormat, the latter ngx-translate. Before you assume your problem is with ngx-translate-messageformat-compiler, please consult these ressources:

• Get help on the message syntax for your translation strings: https://messageformat.github.io/messageformat/page-guide
• Get help on using ngx-translate (loading translations, using HTML tags in your strings, translate pipe vs. directive, etc.): https://github.com/ngx-translate/core

Here's two important differences to ngx-translate's default syntax when using MessageFormat:

• You lose the ability to access object properties in your placeholders: 'Hello {name.first} {name.last}' won't work.
• Simple placeholders are enclosed in single curly braces instead of double curly braces: Hello {name}

This library also exports TranslateMessageFormatDebugCompiler, which you can use as a drop-in replacement for the regular TranslateMessageFormatCompiler. The debug compiler will log to the console whenever a translation string is compiled to an interpolation function, and whenever such a function is called (with interpolation parameters) to compute the final translated string. The logs may help you figuring out which translation produces an error and the timing of when the individual steps happen.

Here's an example to get you started:

Example

Translation strings:

{
  "things": "There {count, plural, =0{is} one{is} other{are}} {count, plural, =0{} one{a} other{several}} {count, plural, =0{nothing} one{thing} other{things}}",
  "people": "{gender, select, male{He is} female{She is} other{They are}} {how}"
}

View template:

<ul>
  <li translate [translateParams]="{ count: 0 }">things</li>
  <li translate [translateParams]="{ count: 1 }">things</li>
  <li>{{'things' | translate:"{ count: 2 }"}}</li>
</ul>
<ul>
  <li translate [translateParams]="{ gender: 'female', how: 'influential' }">people</li>
  <li translate [translateParams]="{ gender: 'male', how: 'funny' }">people</li>
  <li>{{'people' | translate:"{ how: 'affectionate' }"}}</li>
</ul>

Note that this illustrates using both the directives and the pipe provided by ngx-translate. You don't have to mix them, obviously.

Output:

- There is nothing
- There is a thing
- There are several things

- She is influential
- He is funny
- They are affectionate

About

If you're here, you probably know what you're looking for. If you do wonder what this is, here's a brief explanation.

ICU Message Format is a standardized syntax for dealing with the translation of user-visible strings into various languages that may have different requirements for the correct declension of words (e.g. according to number, gender, case) - or to simplify: pluralization.

Messageformat.js is a compliant implementation for Javascript.

Back in AngularJS, angular-translate, formerly by @PascalPrecht, provided support for ICU syntax using messageformat.js. This compiler "plugin" adds the same rich pluralization support to the excellent ngx-translate for Angular (2+). Thanks to @ocombe for his work and his supporting pluggable compilers in the core. Thanks also to @PascalPrecht for suggesting a contribution when I talked to him about this at Jazoon.

Changelog

[4.1.2] - 2018-05-28

Fixed

• 4.1.1 was missing README in published package