Copy SearchContextComponent to ServerItemPaginationComponent to ease BL8 upgrade path

[maxkadel]

• Copy Blacklight::SearchContextComponent to Blacklight::SearchContext::ServerItemPaginationComponent to make it easier to upgrade from Blacklight 7 to Blacklight 8
• Update signature for ServerItemPaginationComponent to include current_document to ease upgrade path (not yet used in the class)
• Add deprecation warning for Blacklight::SearchContextComponent

Closes #3313

[cbeer]

Blacklight 8 has this as:

Suggested change

	@search_context.present? && (@search_context[:prev] || @search_context[:next])
	@search_context.present? && (@search_context[:prev] || @search_context[:next] || total.positive?) && (@search_session['document_id'] == @current_document_id)

Should this match, or is there a reason this is different?

[maxkadel]

I tried that version and it wasn't compatible with Blacklight 7.

My hope with this PR is that we will be able to add a component to replace our custom pagination partial that will work with both Blacklight 7 and Blacklight 8 without significant revisions when upgrading between versions.

[jrochkind]

I think I follow what's going on, but can you briefly explain how this eases BL8 upgrade path?

Also, there are no tests here -- Can you explain your attitude toward tests here? Perhaps we don't need tests, because existing tests cover all necessary things to test, that existing tests continue to be green under this refactor is sufficient? I'm not sure.

[maxkadel]

I think I follow what's going on, but can you briefly explain how this eases BL8 upgrade path?

Also, there are no tests here -- Can you explain your attitude toward tests here? Perhaps we don't need tests, because existing tests cover all necessary things to test, that existing tests continue to be green under this refactor is sufficient? I'm not sure.

My sense was that the existing tests were sufficient for the refactor, but I can try to write some new ones or pull from main for the components.

[jrochkind]

Oh don't add new tests on my account, I was just confirming it was intentional not to include any,that's fine with me!

[maxkadel]

I think I follow what's going on, but can you briefly explain how this eases BL8 upgrade path?

Sorry, realized I didn't explicitly respond to this part @jrochkind.

We have a custom partial for our _previous_next_doc. To upgrade we need to migrate this to a view component. For it to work on Blacklight 7 right now, that view component needs to be a SearchContextComponent (or inherit from it), but for it to work in Blacklight 8 it needs to be a ServerItemPaginationComponent, which does not exist in Blacklight 7. We're trying to find a way to have code that will work in future with Blacklight 8, but that will continue to work with Blacklight 7 in the meantime.

Also, having accurate deprecation statements is helpful! But it's hard when they say to use a thing you cannot actually use!

[sandbergja]

Thanks, @maxkadel !

[sandbergja]

I like this approach of inheriting from the Blacklight 7 component, and providing an interface that is compatible with the Blacklight 8 component!

[sandbergja]

👍🏻