Created ListableNotificationObject

[alexandrevryghem]

Description

@listableObjectsComponents could not handle failed RemoteData objects. To fix this a new component and his model were created, they can be used to display error messages (also works for success, info and warning messages) in lists in between the successful RemoteData objects.

(To display error notifications like above extra configuration is needed. You will need to iterate over your list of RemoteData objects to ensure that you only return the payload of the RemoteData<T> if it exists , if it doesn't exist you need to return a new ListableNotificationObject)

Instructions for Reviewers

List of changes in this PR:

• Created the ListableNotificationObject
• Created resource type LISTABLE_NOTIFICATION_OBJECT
• (Also added another commit to this PR, it's an improvement regarding the PR Add more themed components #1674 where the ExpandableNavbarSectionComponent was not present in the ENTRY_COMPONENTS. This caused it to sometimes load to slow which in turn caused some layout issues)

Guidance for how to test or review this PR:

• Create a ds-listable-notification-object on the home page and give with value new ListableNotificationObject(NotificationType.Error, 'Error message') for the field object.
• An error notification should be visible.

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.

[tdonohue]

@alexandrevryghem : I gave this a review today, and while the code looks reasonable, I'm not understanding how this is supposed to work in the codebase.

I expected that this new ListableNotificationObject would be used elsewhere in our code to automatically trigger a ListableNotificationObject to be created if the corresponding ListableObject could not be loaded (based on the screenshot you show above).

However, it appears this new ListableNotificationObject is unused in our codebase & the only way to use it would be to create custom code. Is that accurate? Or, am I misunderstanding how this is used by our codebease.

If this ListableNotificationObject is unused at this time, then I'd recommend we wait to add it into the codebase until there is a real use case in the DSpace codebase.

[tdonohue]

This appears to be a duplicative i18n key. It already exists on line 4582, so it can be removed from this line

[alexandrevryghem]

The ListableNotificationObject is now used in DSOSelectorComponent when no/new results cannot be retrieved. This error can be simulated by turning off Solr.

To test this you need to click on add Item/Collection/Community in the admin sidebar and when you see the results you have loaded the first page of results you need to stop Solr. When you scroll down the next page DSO objects won't be successfully retrieved and an error will be displayed in between other DSO objects. If you start Solr back up you can click on the error notification and the error message should disappear and the next DSO objects will be added to the list.

[tdonohue]

👍 Thanks @alexandrevryghem ! I gave this another look today & I was able to successfully test it using this "New -> Item" popup (and stopping Solr immediately after loading that page). After I restarted Solr, clicking on the "Something went wrong.." message loaded the next results.