docs(data): add document about how customize a entityCollection level property of ngrx-data

[JiaLiPassion]

PR Checklist

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• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Add documentation about how to customize a EntityCollection level property. Such as in my use case, I want to add paging information in EntityCollection level, but current document can only add an additional property in initialization, there is no document about who to get the property from backend.

[ngrxbot]

Preview docs changes for 428e48a at https://previews.ngrx.io/pr1921-428e48a/

[brandonroberts]

Thanks for the PR @JiaLiPassion! Something is being formatted incorrectly in the preview starting at bullet 3 that throws off the rest of the sections.

[JiaLiPassion]

@brandonroberts, thanks, I fixed it, please review.

[ngrxbot]

Preview docs changes for 1776114 at https://previews.ngrx.io/pr1921-1776114/

[JiaLiPassion]

@timdeschryver, thanks for the review, I have updated the doc!

[ngrxbot]

Preview docs changes for 1149354 at https://previews.ngrx.io/pr1921-1149354/

[timdeschryver]

I went over it one more time and found some small improvements.
Besides these, LGTM and I learned something new 👍

[JiaLiPassion]

@timdeschryver, thank you for the detailed review, I updated the doc!

[ngrxbot]

Preview docs changes for db7d7c6 at https://previews.ngrx.io/pr1921-db7d7c6/

[ngrxbot]

Preview docs changes for 6a20c14 at https://previews.ngrx.io/pr1921-6a20c14/

[timdeschryver]

LGTM, I think the typos are fixed.
Not very familiar with ngrx/data, an extra pair of eyes would be helpful here 🙂

[wesleygrimes]

Just a few more changes

[JiaLiPassion]

@wesleygrimes, thanks, sorry, I didn't see the changes you requested, could you check it?

[wesleygrimes]

Jia,

Nice work. Here are my suggestions.

Thanks,
Wes

[wesleygrimes]

@wesleygrimes, thanks, sorry, I didn't see the changes you requested, could you check it?

Sorry about that, they should be there now.

[JiaLiPassion]

@wesleygrimes, thanks for the review, I have updated the doc.

[wesleygrimes]

Need spacing between Step and Step Number. For some reason, GitHub would not let me suggest fix on Step3 but that should be fixed as well.

Thanks!
Wes

[JiaLiPassion]

@wesleygrimes, sure, thanks, I have fixed those 3 Steps.

[wesleygrimes]

One more round of changes, Thanks Jia!

[ngrxbot]

Preview docs changes for f9325e4 at https://previews.ngrx.io/pr1921-f9325e4/

[wesleygrimes]

LGTM

[JiaLiPassion]

@wesleygrimes, thanks, I will use Grammarly.

[ngrxbot]

Preview docs changes for db19d4e at https://previews.ngrx.io/pr1921-db19d4e/

[AdditionAddict]

@JiaLiPassion I think this needs an update to step 1.

The default QUERY_MANY_SUCCESS reducer is expecting action.payload.data to be an array of entities but the QUERY_MANY action action.payload.data will be whatever the api returns.

Say it returns

interface QueryManyAPIResponse {
total: number,
entities: T[]
}

You can add a property total to the action payload but action.payload.data needs to be the entities if you want the default reducer for a query many success to work.

@Injectable()
export class AdditionalPersistenceResultHandler  extends DefaultPersistenceResultHandler {

    handleSuccess(originalAction: EntityAction): (data: any) => Action {
        const actionHandler = super.handleSuccess(originalAction);

        return function(data: any) {
            /** Default success action */
            const successAction = actionHandler.call(this, data);

            /** Change payload for query many */
            if (successAction && data && data.total) {
                (successAction as any).payload.total = data.total;
            }
            if (successAction && data && data.entities) {
                (successAction as any).payload.data = data.entities;
            }

            return action;
        };
    }
}

Also AdditionalPropertyPersistenceResultHandler changes its name to AdditionalPersistenceResultHandler in step 3. I suggest updating step 1 to AdditionalPersistenceResultHandler