Make the size of a browse result page configurable.

[mwoodiupui]

Description

Invent a new configuration property to control the number of results per page when displaying browse results.

Instructions for Reviewers

List of changes in this PR:

• Create a new configuration property browseBy.pageSize.
• Define a default value wherever browseBy is being configured.
• Replace hard-coded "20" with the value of this property in the browse-by-metadata component.

Checklist

• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes TSLint validation using yarn run lint
• My PR doesn't introduce circular dependencies
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• If my PR includes new, third-party dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.

[artlowel]

Thanks @mwoodiupui

The code looks good, and it works as it should. One strange thing though is that you can't use a number that isn't part of the dropdown of page-sizes on the browse page. It will be rounded to the closest match.

I'm not saying you should change that in this PR (e.g. by making those options configurable as well), but it's likely a good idea to make that clear in the comments

[artlowel]

Thanks @mwoodiupui!

[artlowel]

Sorry, I know I already approved, but I noticed something wile reviewing the other RPP PR, I missed here:

[artlowel]

It's better to inject the environment using

@Inject(APP_CONFIG) protected appConfig: AppConfig

in the constructor, and then use this.appConfig.browseBy.pageSize later on. That makes it easier for us to mock the environment in tests.

[mwoodiupui]

@artlowel "Error: 121:3 error Angular will not invoke the ngOnInit lifecycle method within @Injectable() classes @angular-eslint/contextual-lifecycle"

Suggestions?

[artlowel]

@mwoodiupui I haven't seen it before, but I'd bet the issue is the @Injectable() you added at the top. that's not needed. The @component() decorator already ensures you can use injected services in the constructor.

[artlowel]

Thanks @mwoodiupui!

[tdonohue]

👍 Thanks @mwoodiupui !