Enhance the mat-paginator so the total length can be masked.

[tosehee]

Feature Description

Provide the way to mask the 'total length'.

Use Case

With large data set, getting the count from the backend database is slow. We'd like to mask the "total length", so the users can paginate without having to know the max length. The end user would be able to continue to paginate until there is no results from the backend.

Two issues

1. You wouldn't know the actual max length.
2. If the last page set returns the same as the page size, then it would still allow to paginate to next page. However, there would be no results.

The end user who can live with these two issues can simply mask the total length by specifying the display label such as "More" or "..."

Example.

200-300 (More) "<" ">"
Or
200-300 (...) "<" ">"

<mat-paginator [maskTotal]="true" [maskTotalLabel]="'More'"

[crisbeto]

This seems reasonable, but if it's in a separate input it could conflict with the length. We could make it so length accepts null. What do you think @jelbourn?

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[pschoen-itsc]

I implemented such a feature for ourselves and you don't need to nullify the length param. The idea is in your backend you define a reasonable limit. Until this limit everything works like before. If a query would yield more elements than the limit you return this information the the frontend (limited: bool) and set length=limit. Now the paginator can make this visible to the user that there are even more results available. When you page through the results you also increase the limit each time by the page size.

Example with some number:
total count: 23867
page size: 500
limit: 10000

Paginators:
1-500 of 10000+
501-1000 of 10500+
15001-15500 of 23867

Effectively you just have to set the '+' (or any other string) when the backend signals that the current count is limited.

I know the vote over a year ago failed and you have to consider the burden to maintain additional code, but I would be open the create a PR with the implementation I described.