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.

    Up until now, grouping/sorting worked in conjunction with each other. In 13.2 version, a new behavior which decouples grouping 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 context menu added for sorting using igx-tree-grid's contextMenu Output.

    EXAMPLE
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    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>
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    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 }
]);
typescript

    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();
typescript

    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.

    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() 
        }
    ];
}
typescript

    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.

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    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>
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    • 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>
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    • 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>
html

    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';
scss

    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
);
scss

    Instead of hardcoding the color values like we just did, we can achieve greater flexibility in terms of colors by using the palette and color functions. Please refer to Palettes topic for detailed guidance on how to use them.

    The last step is to include the component mixins:

    @include css-vars($custom-theme);
scss

    Demo

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

    API References

    Additional Resources

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