Blazor Grid Summaries

    The Blazor IgbGrid has a summaries feature that functions on a per-column level as group footer. Blazor grid summaries is powerful feature which enables the user to see column information in a separate container with a predefined set of default summary items, depending on the type of data within the column or by implementing a custom template in the IgbGrid.

    Blazor Grid Summaries Overview Example

    [!Note] The summary of the column is a function of all column values, unless filtering is applied, then the summary of the column will be function of the filtered result values

    IgbGrid summaries can also be enabled on a per-column level in Ignite UI for Blazor, which means that you can activate it only for columns that you need. IgbGrid summaries gives you a predefined set of default summaries, depending on the type of data in the column, so that you can save some time:

    For string and boolean DataType, the following function is available:

    • Count

    For number, currency and percent data types, the following functions are available:

    • Count
    • Min
    • Max
    • Average
    • Sum

    For date data type, the following functions are available:

    • Count
    • Earliest
    • Latest

    All available column data types could be found in the official Column types topic.

    IgbGrid summaries are enabled per-column by setting HasSummary property to true. It is also important to keep in mind that the summaries for each column are resolved according to the column data type. In the IgbGrid the default column data type is string, so if you want number or date specific summaries you should specify the DataType property as number or date. Note that the summary values will be displayed localized, according to the grid Locale and column PipeArgs.

    <IgbGrid>
        <IgbColumn Field="EmployeeID" DataType="GridColumnDataType.Number" HasSummary="true"></IgbColumn>
        <IgbColumn Field="FirstName" HasSummary="true"></IgbColumn>
        <IgbColumn Field="LastName" HasSummary="true"></IgbColumn>
        <IgbColumn Field="Title" HasSummary="true"></IgbColumn>
</IgbGrid>

    The other way to enable/disable summaries for a specific column or a list of columns is to use the public method EnableSummaries/DisableSummaries of the IgbGrid.

     <IgbGrid @ref=grid Id="grid" AutoGenerate="false">
        <IgbColumn Field="EmployeeID" DataType="GridColumnDataType.Number" HasSummary="true"></IgbColumn>
        <IgbColumn Field="FirstName" Sortable="true" HasSummary="true"></IgbColumn>
        <IgbColumn Field="LastName" Sortable="false" DisablePinning="true" DisableHiding="true" HasSummary="true"></IgbColumn>
        <IgbColumn Field="Title" Sortable="true" DisablePinning="false" DisableHiding="true"></IgbColumn>
</IgbGrid>

@code {
    public async void DisableSummaries()
    {
        object[] disabledSummaries = { "EmployeeID" };
        await this.grid.DisableSummariesAsync(disabledSummaries);
    }
}

    Custom Grid Summaries

    If these functions do not fulfill your requirements you can provide a custom summary for the specific columns.

    
//In JavaScript
class WebGridDiscontinuedSummary {
    operate(data, allData, fieldName) {
        const discontinuedData = allData.filter((rec) => rec['Discontinued']).map(r => r[fieldName]);
        const result = [];
        result.push({
            key: 'products',
            label: 'Products',
            summaryResult: data.length
        });
        result.push({
            key: 'total',
            label: 'Total Items',
            summaryResult: data.length ? data.reduce((a, b) => +a + +b) : 0
        });
        result.push({
            key: 'discontinued',
            label: 'Discontinued Products',
            summaryResult: allData.map(r => r['Discontinued']).filter((rec) => rec).length
        });
        result.push({
            key: 'totalDiscontinued',
            label: 'Total Discontinued Items',
            summaryResult: discontinuedData.length ? discontinuedData.reduce((a, b) => +a + +b) : 0
        });
        return result;
    }
}

    As seen in the examples, the base classes expose the Operate method, so you can choose to get all default summaries and modify the result, or calculate entirely new summary results.

    The method returns a list of IgbSummaryResult.

    and take optional parameters for calculating the summaries. See Custom summaries, which access all data section below.

    [!Note] In order to calculate the summary row height properly, the Grid needs the Operate method to always return an array of IgbSummaryResult with the proper length even when the data is empty.

    And now let's add our custom summary to the column UnitsInStock. We will achieve that by setting the Summaries` property to the class we create below.

    <IgbGrid 
        AutoGenerate="true"
        Name="grid"
        @ref="grid"
        Data="NwindData"
        PrimaryKey="ProductID"
        ColumnInitScript="WebGridCustomSummary">
</IgbGrid>

// In Javascript
igRegisterScript("WebGridCustomSummary", (event) => {
    if (event.detail.field === "UnitsInStock") {
        event.detail.summaries = WebGridDiscontinuedSummary;
    }
}, false);

    Custom summaries, which access all data

    Now you can access all Grid data inside the custom column summary. Two additional optional parameters are introduced in the SummaryOperand Operate method. As you can see in the code snippet below the operate method has the following three parameters:

    • columnData - gives you an array that contains the values only for the current column
    • allGridData - gives you the whole grid data source
    • fieldName - current column field
    class WebGridDiscontinuedSummary {
    operate(data, allData, fieldName) {
        const discontinuedData = allData.filter((rec) => rec['Discontinued']).map(r => r[fieldName]);
        result.push({
            key: 'totalDiscontinued',
            label: 'Total Discontinued Items',
            summaryResult: discontinuedData.length ? discontinuedData.reduce((a, b) => +a + +b) : 0
        });
        return result;
    }
}

    Summary Template

    Summary targets the column summary providing as a context the column summary results.

    <IgbColumn HasSummary="true" SummaryTemplateScript="SummaryTemplate">
</IgbColumn>

igRegisterScript("SummaryTemplate", (ctx) => {
    var html = window.igTemplating.html;
    return html`<div>
    <span> ${ctx.implicit[0].label} - ${ctx.implicit[0].summaryResult} </span>
</div>`
}, false);

    When a default summary is defined, the height of the summary area is calculated by design depending on the column with the largest number of summaries and the display density of the grid. Use the SummaryRowHeight input property to override the default value. As an argument it expects a number value, and setting a falsy value will trigger the default sizing behavior of the grid footer.

    Summaries with Group By

    When you have grouped by columns, the IgbGrid allows you to change the summary position and calculation mode using the SummaryCalculationMode and SummaryPosition properties. Along with these two properties the IgbGrid exposes and ShowSummaryOnCollapse property which allows you to determine whether the summary row stays visible when the group row that refers to is collapsed.

    The available values of the SummaryCalculationMode property are:

    • RootLevelOnly - Summaries are calculated only for the root level.
    • ChildLevelsOnly - Summaries are calculated only for the child levels.
    • RootAndChildLevels - Summaries are calculated for both root and child levels. This is the default value.

    The available values of the SummaryPosition property are:

    • Top - The summary row appears before the group by row children.
    • Bottom - The summary row appears after the group by row children. This is the default value.

    The ShowSummaryOnCollapse property is boolean. Its default value is set to false, which means that the summary row would be hidden when the group row is collapsed. If the property is set to true the summary row stays visible when group row is collapsed.

    [!Note] The SummaryPosition property applies only for the child level summaries. The root level summaries appear always fixed at the bottom of the IgbGrid.

    Demo

    Keyboard Navigation

    The summary rows can be navigated with the following keyboard interactions:

    • UP - navigates one cell up.
    • DOWN - navigates one cell down.
    • LEFT - navigates one cell left.
    • RIGHT - navigates one cell right.
    • CTRL + LEFT or HOME - navigates to the leftmost cell.
    • CTRL + RIGHT or END - navigates to the rightmost cell.

    Styling

    In addition to the predefined themes, the grid could be further customized by setting some of the available CSS properties. In case you would like to change some of the colors, you need to set a class for the grid first:

    <IgbGrid Class="grid"></IgbGrid>

    Then set the related CSS properties for that class:

    .grid {
    --ig-grid-summary-background-color:#e0f3ff;
    --ig-grid-summary-focus-background-color: rgba( #94d1f7, .3 );
    --ig-grid-summary-label-color: rgb(228, 27, 117);
    --ig-grid-summary-result-color: black;
}

    Demo

    API References

    Additional Resources

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