LokiJS: when using DynamicView().branchResultSet with applySort it doesn't sort the collection

Question

I am having a problem getting data from a branchResultSet after using the applySort on the view. The reason I am using that is because I want a limit of 10 records back and not the whole thing for better performance. When I use only the data method it works as expected.

Example code:

switch() {
  // ...
  case 'Name':
  // This code was added elsewhere. I added this as an example of how I
  // initialize the variable studentView.
  this.studentView = studentColl.addDynamicView('view');
  /////////////////////////////////////////////////////

  this.studentsView.applySort((a: IStudent, b: IStudent) => {
    if (a.firstName.toLowerCase() < b.firstName.toLowerCase()) {
      return -1;
    }
    if (a.firstName.toLowerCase() > b.firstName.toLowerCase()) {
      return 1;
    }
    return 0;
  }).applySort((a, b) => {
    if (a.lastName.toLowerCase() < b.lastName.toLowerCase()) {
      return -1;
    }
    if (a.lastName.toLowerCase() > b.lastName.toLowerCase()) {
      return 1;
    }
    return 0;
  });
  break;
};

this.students = this.studentsView.branchResultset(lokiViews.viewPaging, { pageStart: 0, pageSize: 10 }).data();
//...

I expected to see collection sorted.

If I use this.studentView.data(), I see the data sorted as expected.

When I use applyWhere it works as expected.

Using the branchResultSet method also didn't work with applySimpleSort(param).

applyFind also works as expected.

My only issues have been with both Sort methods.

I'm using StencilJS and TypeScript but I don't believe the issue is with those frameworks because I tried running similar code on a Vanilla HTML-JavaScript and had the same problem.

Answer 1

The underlying code (Resultset.prototype.copy) does not not perform the sort before branching. You can do it though.

if (this.studentsView.sortDirty || this.studentsView.resultsdirty) {
    this.studentsView.performSortPhase({
        suppressRebuildEvent: true
    });
}
this.students = this.studentsView.branchResultset(lokiViews.viewPaging, { pageStart: 0, pageSize: 10 }).data();