Angular Tree Grid Sorting

    In Ignite UI for Angular Tree Grid, data sorting is enabled on a per-column level, meaning that the igx-tree-grid can have a mix of sortable and non-sortable columns. Performing angular sort actions enables you to change the display order of the records based on specified criteria.

    Note

    Up until now, grouping/sorting worked in conjuction with each other. In 13.2 version, a new behavior which decouples gropuing from sorting is introduced. For example - clearing the grouping will not clear sorting expressions in the grid or vice versa. Still, if a column is both sorted and grouped, grouped expressions take precedence.

    Angular Tree Grid Sorting Overview Example

    Additionally there is a custom contextmenu added for sorting using igx-tree-grid's contextMenu Output.

    This is done via the sortable input. With the Tree Grid sorting, you can also set the sortingIgnoreCase property to perform case sensitive sorting:

    <igx-column field="Name" header="Order Product" [dataType]="'string'" sortable="true"></igx-column>

    Sorting Indicators

    Having a certain amount of sorted columns could be really confusing if there is no indication of the sorted order.

    The IgxTreeGrid provides a solution for this problem by indicating the index of each sorted column.

    Sorting through the API

    You can sort any column or a combination of columns through the Tree Grid API using the Tree Grid sort method:

    import { SortingDirection } from 'igniteui-angular';
// import { SortingDirection } from '@infragistics/igniteui-angular'; for licensed package

// Perform a case insensitive ascending sort on the ProductName column.
this.treeGrid.sort({ fieldName: 'Name', dir: SortingDirection.Asc, ignoreCase: true });

// Perform sorting on both the ProductName and Price columns.
this.treeGrid.sort([
    { fieldName: 'Name', dir: SortingDirection.Asc, ignoreCase: true },
    { fieldName: 'UnitPrice', dir: SortingDirection.Desc }
]);
    Note

    Sorting is performed using our DefaultSortingStrategy algorithm. Any IgxColumnComponent or ISortingExpression can use a custom implementation of the ISortingStrategy as a substitute algorithm. This is useful when custom sorting needs to be defined for complex template columns, or image columns, for example.

    As with the filtering behavior, you can clear the sorting state by using the clearSort method:

    // Removes the sorting state from the ProductName column
this.treeGrid.clearSort('Name');

// Removes the sorting state from every column in the Tree Grid
this.treeGrid.clearSort();
    Note

    The sortStrategy of the Tree Grid is of different type compared to the sortStrategy of the column, since they work in different scopes and expose different parameters.

    Note

    The sorting operation DOES NOT change the underlying data source of the Tree Grid.

    Initial sorting state

    It is possible to set the initial sorting state of the Tree Grid by passing an array of sorting expressions to the sortingExpressions property of the Tree Grid.

    public ngAfterViewInit(): void {
    this.treeGrid.sortingExpressions = [
        { 
            dir: SortingDirection.Asc, fieldName: 'UnitPrice',
            ignoreCase: true, strategy: DefaultSortingStrategy.instance() 
        }
    ];
}
    Note

    If values of type string are used by a column of dataType Date, the Tree Grid won't parse them to Date objects and using Tree Grid sorting won't work as expected. If you want to use string objects, additional logic should be implemented on an application level, in order to parse the values to Date objects.

    Sorting Indicators Templates

    The sorting indicator icon in the column header can be customized using a template. The following directives are available for templating the sorting indicator for any sorting state (ascending, descending, none):

    • IgxSortHeaderIconDirective – re-templates the sorting icon when no sorting is applied.
    <ng-template igxSortHeaderIcon>
    <igx-icon>unfold_more</igx-icon>
</ng-template>
    • IgxSortAscendingHeaderIconDirective – re-templates the sorting icon when the column is sorted in ascending order.
    <ng-template igxSortAscendingHeaderIcon>
    <igx-icon>expand_less</igx-icon>
</ng-template>
    • IgxSortDescendningHeaderIconDirective – re-templates the sorting icon when the column is sorted in descending order.
    <ng-template igxSortDescendingHeaderIcon>
    <igx-icon>expand_more</igx-icon>
</ng-template>

    Styling

    To get started with styling the sorting behavior, we need to import the index file, where all the theme functions and component mixins live:

    @use "igniteui-angular/theming" as *;

// IMPORTANT: Prior to Ignite UI for Angular version 13 use:
// @import '~igniteui-angular/lib/core/styles/themes/index';

    Following the simplest approach, we create a new theme that extends the grid-theme and accepts the $sorted-header-icon-color and sortable-header-icon-hover-color parameters.

    $custom-theme: grid-theme(
    $sorted-header-icon-color: #ffb06a,
    $sortable-header-icon-hover-color: black
);

    The last step is to include the component mixins:

     @include grid($custom-theme);
    Note

    If the component is using an Emulated ViewEncapsulation, it is necessary to penetrate this encapsulation using ::ng-deep:

    :host {
   ::ng-deep {
       @include grid($custom-theme);
   }
}

    Defining a color palette

    Instead of hardcoding the color values like we just did, we can achieve greater flexibility in terms of colors by using the igx-palette and igx-color functions.

    igx-palette generates a color palette based on the primary and secondary colors that are passed:

    $black-color: black;
$orange-color: #ffb06a;

$custom-palette: palette($primary: $black-color, $secondary: $orange-color);

    And then with igx-color we can easily retrieve color from the palette.

    $custom-theme: grid-theme(
    $sorted-header-icon-color: color($custom-palette, "secondary", 500),
    $sortable-header-icon-hover-color: color($custom-palette, "primary", 500)
);
    Note

    The igx-color and igx-palette are powerful functions for generating and retrieving colors. Please refer to Palettes topic for detailed guidance on how to use them.

    Using Schemas

    Going further with the theming engine, you can build a robust and flexible structure that benefits from schemas. A schema is a recipe of a theme.

    Extend one of the two predefined schemas, that are provided for every component, in this case - _light-grid:

    // Extending the light grid schema
$custom-grid-schema: extend($_light-grid,
    (
        sorted-header-icon-color: (igx-color:('secondary', 500)),
        sortable-header-icon-hover-color: (igx-color:('primary', 500))
    )
);

    In order to apply our custom schema we have to extend one of the globals (light or dark), which is basically pointing out the components with a custom schema, and after that add it to the respective component themes:

    // Extending the global light-schema
$my-custom-schema: extend($light-schema, 
    (
        igx-grid: $custom-grid-schema
    )
);

// Defining our custom theme with the custom schema
$custom-theme: grid-theme(
  $palette: $custom-palette,
  $schema: $my-custom-schema
);

    Don't forget to include the themes in the same way as it was demonstrated above.

    Demo

    Note

    The sample will not be affected by the selected global theme from Change Theme.

    API References

    Additional Resources

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