Core: Add check for presence of a translation

[hoeni]

Current behavior

There is no way to be certain about the existence of a translation for a specific key. The best thing I can do is checking if the translation is the same as the given key:
if (this.translate.instant(myKey) === myKey) { ... }
However, besides not being pretty, this cannot detect the case when the translation really is the same as the key.

Expected behavior

It would be nice to have a safe and concise test for the presence of a translation.

How do you think that we should implement this?

if(this.translate.hasTranslation(key)) { ... }

Nice bonus: Give it an optional argument for testing another language instead of the current:
hasTranslation(translationKey: string, language?: string): boolean

[SeeeD]

Another nice feature would be not triggering the "MissingTranslationsHandler" when calling this method you suggested.
I'm using it like you above and I filter some translation-terms from my "MissingTranslationsHandler". That's some kind of dirty for me :(

[chr33z]

Hey, I wrote a Visual Studio Code Extension that shows translations inline in the codebase. Maybe this can help during development as you can see if a certain identifier has a corresponding translation in a .json file.

https://marketplace.visualstudio.com/items?itemName=chr33z.lingua-vscode

[spixy]

You can easily check with:

import { TranslateService } from '@ngx-translate/core';

constructor(private translateService: TranslateService) { }


public hasTranslation(translationKey: string, language?: string): boolean {
  const translations = this.translateService.translations[language || this.translateService.currentLang];
  return translations && translations[translationKey] !== undefined;
}

[M4tiz]

A slightly improved version of @spixy where you can reference deep keys via dot notation eg. VERY.DEEP.TRANSLATION

import { TranslateService } from '@ngx-translate/core';

constructor(private translateService: TranslateService) { }


public hasTranslation(translationKey: string, language?: string): boolean {
        const translation: object | string = this.translateService.translations[language || this.translateService.currentLang];
        const value = key
            .split('.')
            .reduce((t, k) => t[k] || {}, translation || {});
        return value !== undefined;
}

[mavriksc]

@M4tiz there are some errors there and i'm able to reference deep keys with @spixy code