Count unique occurrences of a column when using distinct to calculate pagination details

[davidgf]

• Related Issues: Pagination details are wrong when selecting distinct values of a column #1948

Introduction

The pagination plugin is returning the wrong rowCount when the query contains a SELECT DISTINCT statement.

Motivation

In one of the projects we're working on, we need to paginate different occurrences of a column within a table. When we reached the last page, we've noticed that we were still getting pagination details. Not only so, but if we requested a page with an offset greater that the total, we still got pagination details along with an empty set of results. This was due to calculating the rowCount incorrectly.

Fixes #1948.

Proposed solution

When counting the total number of rows, the pagination plugin is excluding all columns statements from the grouping columns, even when they are part of a distinct statement. Therefore, the resulting count query selects all the records in the table, rather than only unique occurrences of a column in that table, and returning a wrong rowCount. The proposed solution simply keeps columns statements when distinct is true.

[ricardograca]

Looks good to me. Thanks for the fix.

[davidgf]

Thank you for accepting it 😄 Do you know when the fix could be released in npm?

[ricardograca]

Possibly in the next version (1.0.0), if not earlier.

[ricardograca]

This was released in version 0.15.0.