feat: use the metadata with correct language

[pcg-kk]

feat: provide a language support for community pages

References

Add references/links to any related issues or PRs. These may include:

• Fixes Enabling translation of collection's/community's names and description #2056
• Requires replace PATCH request on /metadata now supports multiple values DSpace#9610 (if a REST API PR is required to test this)

Description

In this PR we provide an mechanism to upload more than one language for communities and collections pages. User can define a page in all supported by DSpace languages from an customer environment file.

Instructions for Reviewers

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List of changes in this PR:

• We provide an form to save multiple languages
• We changed a way to display texts from specific languages
• We modify the backend API to save more than one metadata for each type

Include guidance for how to test or review your PR. This may include: steps to reproduce a bug, screenshots or description of a new feature, or reasons behind specific changes.

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[github-actions]

Hi @pcg-kk,
Conflicts have been detected against the base branch.
Please resolve these conflicts as soon as you can. Thanks!

[artlowel]

Thanks @pcg-kk!

This works well. I like the decision of putting the translation form next to the original, that makes it very easy to use!

This PR does change the behavior for languages that aren't (entirely) translated though. Currently it would fall back to the default language for fields that don't have a value in the current language. With this PR, fields that don't have a value in the current language are omitted. It would be good to try and retain the original behavior.

I also have a few minor inline comments.

[artlowel]

I'd create a local property in the component to store translateService.currentLang, and initialize it in ngOnInit that will likely be more efficient than accessing the service from the HTML. This goes for all the components in this PR that use translateService.currentLang from the HTML

[pcg-kk]

Fixed

[artlowel]

Thanks @pcg-kk, but I see it's still used in a bunch of other components. I'd do a search in your IDE for "translateservice.currentlang" in HTML files, and move it to the ts file for all of them.

[minurmin]

The line

dspace-angular/src/app/collection-page/collection-page.component.html

Line 50 in 88345f5

[content]="collection.copyrightText"

should include (translateService.currentLang) (as in community-page.component.html, https://github.com/DSpace/dspace-angular/pull/3078/files#diff-df2430517ff5adc042caccd6792890e6070e1f71221fee6c4fc42c5acfce299dR35 )

Otherwise a text copyrightText(S){return this.firstMetadataValue("dc.rights",{language:S})} would appear at the end of collection page.

[minurmin]

Consider adding only active languages to limit the length of the list. E.g.
this.languages = environment.languages.filter(lang => ((lang.code !== this.defaultLanguageCode) && (lang.active === true)));

[pcg-kk]

Thx - good remark. Fixed

[pcg-kk]

@minurmin , @artlowel thanks a lot for review. I updated the repository to be sync with current main and applied your suggestions.

[minurmin]

This function (and more specifically, the blocks starting here and ending to submitForm.emit) is the only place in this PR that depends on DSpace/DSpace#9610. Based on discussion in server-side PR, you might want to consider implementing this based on PATCH ADD so REST Contract would not have to be changed. For example, something like this (additional checks are probably needed and there is room for optimization as I have limited experience with TypeScript):

const operations: Map<string, AddOperation<{value: string, language: string}>[]> = new Map();

(slightly different form of array because Operations are now iterated instead of values)

if ( keyExistAndAtLeastOneValueIsNotNull) {
  if (operations.has(key)) {
    const fieldOperations: Operation[] = operations.get(key);
    fieldOperations.push({
      op: 'add',
      path: key,
      value: {
        value: fieldModel.value as string,
        language
      }
    });
  } else {
    operations.set(key, [
      {op: 'add',
      path: key,
      value: {
        value: fieldModel.value as string,
        language
      },
    }]);
  }
}

(construct an array of add operations instead of array of values)

let finalOperations: Operation[] = [];
for (let [key,value] of operations) {
  finalOperations.push({op: 'remove', path: key}),
  finalOperations = finalOperations.concat(value);      
};

(before submitForm.emit construct another array that is suitable as such for the emit method instead of operations.values() and includes remove operation to ensure that old fields are cleared)