Angular Data GridRow Grouping - Sorting Groups
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This section provides details on how to configure and customise how row groups are sorted.

Group Sorting

When using Single Group Column or Multiple Group Columns sorting is enabled by default. If you wish to disable sorting this can be achieved by setting sortable = false. In cases where it is preferable to suppress sorting on the Row Group Columns only autoGroupColumnDef.sortable = false can be used.

The example below demonstrates sorting with Multiple Group Columns.

Mixed Group Sorting

By default, columns only apply sorting to their leaf level row data, as such to sort row groups you should apply the sort to the column on which the grouping has been applied.

This creates the side effect that groups can be sorted in multiple directions simultaneously, the group column reflects this by displaying the multi-sort icon when it does not match one or more of the provided columns sort direction.

<ag-grid-angular
    [columnDefs]="columnDefs"
    /* other grid options ... */>
</ag-grid-angular>

this.columnDefs = [
    {
        field: 'year',
        rowGroup: true,
        sort: 'desc',
    },
    {
        field: 'handset',
        rowGroup: true,
        sort: 'asc',
    },
];

In this snippet, sorting on the year or handset column will sort their respective row groups. As the year and handset column have different sorts applied to them, the group column displays the mixed sort icon.

The following example demonstrates mixed group sorting. Note the following:

  • Click the header of the group column to apply a sort, observe how it forces the year and handset columns sort to match.
  • Hold shift and click the header of the year column, observe how the sort direction is now different from the auto column, and the auto column now displays the mixed-sort icon.

Custom Group Sorting

By default, any sort comparator defined on a column that is used to group rows by will also be used by the Group Column. For example, consider the following column definition:

<ag-grid-angular
    [columnDefs]="columnDefs"
    /* other grid options ... */>
</ag-grid-angular>

this.columnDefs = [
     {
         field: 'month',
         rowGroup: true,
         comparator: (a, b) => {
             const months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 
                             'August', 'September','October', 'November', 'December'];

             // sorts 'months' in chronological order
             return months.indexOf(a) - months.indexOf(b);
         },
     },
 ];

As rowGroup = true is defined on this column, the supplied comparator will be used to sort the month column and the Group Column.

The following example demonstrates custom group sorting. Note the following:

  • The month column has a custom sort comparator supplied which sorts months in chronological order.
  • The 'Group' Column uses the comparator defined on the month column definition to sort the row groups.

It is also possible to define a comparator that will be used across all group levels using; autoGroupColumnDef.comparator. This 'shared group comparator' will override over any comparators defined on the underlying columns.

Maintain Group Order

When sorting on non-group columns it may be desirable to maintain the existing group order. This behaviour can be enabled through the groupMaintainOrder grid option as shown below:

<ag-grid-angular
    [columnDefs]="columnDefs"
    [groupDisplayType]="groupDisplayType"
    [groupMaintainOrder]="groupMaintainOrder"
    /* other grid options ... */>
</ag-grid-angular>

this.columnDefs = [
    { field: 'assignee', rowGroup: true, hide: true },
    { field: 'priority', rowGroup: true, hide: true },        
    { field: 'task' },      
];

this.groupDisplayType = 'multipleColumns';

// preserves current group order when sorting on non-group columns
this.groupMaintainOrder = true;

Note that Group Order is not the same as sorting. Maintaining group order will not preserve active group sorts, just the current order of the groups. However, when sorting on group columns the group order will be changed based on the sort.

The following example demonstrates how groupMaintainOrder works. Note the following:

  • groupMaintainOrder = true is defined on the grid options supplied to the grid.
  • Clicking on the 'Task' column header only sorts the tasks without reordering the groups.
  • Sorting on the 'Assignee' or 'Priority' group column headers will reorder the groups.

Next Up

Continue to the next section to learn about Filtering Groups.