Summaries — Flutter DataGrid

Overview

SfDataGrid supports table summary rows via SfDataGrid.tableSummaryRows. Summary values are calculated automatically, but you must override DataGridSource.buildTableSummaryCellWidget to render the summary widget. Summary rows can appear at the top or bottom of the grid.

Summary in a Row (showSummaryInRow: true)

Display a summary for an entire row using a title string with a {Name} placeholder:

SfDataGrid(
  source: employeeDataSource,
  tableSummaryRows: [
    GridTableSummaryRow(
        showSummaryInRow: true,
        title: 'Total Salary: {Sum} for 20 employees',
        columns: [
          GridSummaryColumn(
              name: 'Sum',
              columnName: 'salary',
              summaryType: GridSummaryType.sum)
        ],
        position: GridTableSummaryRowPosition.bottom)
  ],
  columns: columns,
)

Override buildTableSummaryCellWidget in DataGridSource:

@override
Widget? buildTableSummaryCellWidget(
    GridTableSummaryRow summaryRow,
    GridSummaryColumn? summaryColumn,
    RowColumnIndex rowColumnIndex,
    String summaryValue) {
  return Container(
    padding: EdgeInsets.all(15.0),
    child: Text(summaryValue),
  );
}

Summary in a Column (showSummaryInRow: false)

Display summary values in their respective columns:

SfDataGrid(
  source: employeeDataSource,
  tableSummaryRows: [
    GridTableSummaryRow(
        showSummaryInRow: false,
        columns: [
          GridSummaryColumn(
              name: 'Sum',
              columnName: 'salary',
              summaryType: GridSummaryType.sum),
        ],
        position: GridTableSummaryRowPosition.bottom)
  ],
  columns: columns,
)

Summary with Title + Column Values

Show a title spanning columns alongside individual column summaries. Requires showSummaryInRow: false and titleColumnSpan:

GridTableSummaryRow(
    showSummaryInRow: false,
    title: 'Total Employee Count: {Count}',
    titleColumnSpan: 3,
    columns: [
      GridSummaryColumn(
          name: 'Count',
          columnName: 'id',
          summaryType: GridSummaryType.count),
      GridSummaryColumn(
          name: 'Sum',
          columnName: 'salary',
          summaryType: GridSummaryType.sum)
    ],
    position: GridTableSummaryRowPosition.bottom),

Positioning Summary Rows

// Top summary
GridTableSummaryRow(
    showSummaryInRow: false,
    columns: [...],
    position: GridTableSummaryRowPosition.top),

// Bottom summary
GridTableSummaryRow(
    showSummaryInRow: true,
    title: 'Total Salary: {Sum} for 20 employees',
    columns: [...],
    position: GridTableSummaryRowPosition.bottom)

Summary Row Background Color

GridTableSummaryRow(
    color: Colors.indigo,
    showSummaryInRow: true,
    title: 'Minimum Salary: {Minimum} for 20 employees',
    columns: [
      GridSummaryColumn(
          name: 'Minimum',
          columnName: 'salary',
          summaryType: GridSummaryType.minimum)
    ],
    position: GridTableSummaryRowPosition.bottom),

Custom Summary Calculation

Override calculateSummaryValue to implement custom logic (e.g., standard deviation):

@override
String calculateSummaryValue(GridTableSummaryRow summaryRow,
    GridSummaryColumn? summaryColumn, RowColumnIndex rowColumnIndex) {
  String? title = summaryRow.title;
  if (title != null) {
    if (summaryRow.showSummaryInRow && summaryRow.columns.isNotEmpty) {
      for (final GridSummaryColumn summaryColumn in summaryRow.columns) {
        if (title!.contains(summaryColumn.name)) {
          double deviation = 0;
          final List<int> values = getCellValues(summaryColumn);
          if (values.isNotEmpty) {
            int sum = values.reduce((value, element) =>
                value + pow(element - values.average, 2).toInt());
            deviation = sqrt((sum) / (values.length - 1));
          }
          title = title.replaceAll(
              '{${summaryColumn.name}}', deviation.toString());
        }
      }
    }
  }
  return title ?? '';
}

Summary Calculation Types

Type	Description
`GridSummaryType.sum`	Sum of all values in the column
`GridSummaryType.average`	Average of all values in the column
`GridSummaryType.count`	Total number of rows
`GridSummaryType.maximum`	Maximum value in the column
`GridSummaryType.minimum`	Minimum value in the column

Key Property Reference

GridTableSummaryRow Properties

Property	Type	Default	Description
`showSummaryInRow`	`bool`	required	Show summary across full row (`true`) or per-column (`false`)
`title`	`String?`	`null`	Title string with `{Name}` placeholder (used when `showSummaryInRow: true` or with `titleColumnSpan`)
`titleColumnSpan`	`int`	0	How many columns the title should span (requires `showSummaryInRow: false`)
`columns`	`List<GridSummaryColumn>`	required	Summary column definitions
`position`	`GridTableSummaryRowPosition`	required	`top` or `bottom`
`color`	`Color?`	`null`	Background color of the summary row

GridSummaryColumn Properties

Property	Type	Description
`name`	`String`	Identifier used in `title` placeholder (`{name}`)
`columnName`	`String`	Must match a `GridColumn.columnName`
`summaryType`	`GridSummaryType`	Calculation type (sum, average, count, maximum, minimum)

DataGridSource Methods

Method	Description
`buildTableSummaryCellWidget(summaryRow, summaryColumn, rowColumnIndex, summaryValue)`	Override to return widget displaying the summary value
`calculateSummaryValue(summaryRow, summaryColumn, rowColumnIndex)`	Override to implement custom summary calculation logic

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