IgxTreeGrid: display only filtered records

[viktorkombov]

Is your feature request related to a problem? Please describe.

When filtering condition is applied to a column in IgxTreeGrid not only the records that meet specified criteria are displayed but also their parents.

Describe the solution you'd like

I would like to be provided with an option for displaying only the records that meet specified criteria withtout their parents.

[viktorkombov]

As a workaround the requirement can be achieved with a custom filtering strategy:

TYPESCRIPT
export class CustomFilteringStrategy extends TreeGridFilteringStrategy {
    public filter(data: ITreeGridRecord[], expressionsTree: IFilteringExpressionsTree,
        advancedExpressionsTree?: IFilteringExpressionsTree, grid?: GridType): ITreeGridRecord[] {
        return this.customFilterImpl(data, expressionsTree, advancedExpressionsTree, undefined, grid);
    }

    private customFilterImpl(data: ITreeGridRecord[], expressionsTree: IFilteringExpressionsTree,
        advancedExpressionsTree: IFilteringExpressionsTree, parent: ITreeGridRecord, grid?: GridType): TreeGridRecord[] {
        let rec: ITreeGridRecord;
        const res: ITreeGridRecord[] = [];
        …
        if (this.matchRecord(rec, expressionsTree, grid) && this.matchRecord(rec, advancedExpressionsTree, grid)) {
            res.push(rec);
        } else if (rec.children && rec.children.length > 0) {
            rec = this.setCorrectLevelToFilteredRecords(rec);
            res.push(...rec.children);
        }
        ….
        return res;
    }
    …
}

This is a sample that implements the above approach.