JavaScript Data GridRow Grouping - Opening Groups
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This section covers different ways to control how row groups are expanded and collapsed.

Opening Group Levels by Default

To open all groups down to a given group level use the groupDefaultExpanded grid option as shown below:

const gridOptions = {
    columnDefs: [
        { field: 'country', hide: true, rowGroup: true },
        { field: 'year', hide: true, rowGroup: true },
        { field: 'sport' },
        { field: 'total' }
    // all 'country' row groups will be open by default
    groupDefaultExpanded: 1,

    // other grid options ...

In the snippet above, all country row groups will be expanded by default as groupDefaultExpanded = 1.

By default groupDefaultExpanded = 0 which means no groups are expanded by default. To expand all row groups set groupDefaultExpanded = -1.

The example below demonstrates the groupDefaultExpanded behaviour. Note the following:

  • There are two active row groups as the supplied country and year column definitions have rowGroup=true declared.

  • All country row groups are expanded by default as groupDefaultExpanded = 1.

Open Groups by Default

To have groups open by default, implement the grid callback isGroupOpenByDefault. This callback is invoked each time a group is created.

const gridOptions = {
    // expand when year is '2004' or when country is 'United States'
    isGroupOpenByDefault: params => {
        return (params.field == 'year' && params.key == '2004') ||
            (params.field == 'country' && params.key == 'United States');

    // other grid options ...

The params passed to the callback have the IsGroupOpenByDefaultParams interface:

Properties available on the IsGroupOpenByDefaultParams<TData = any, TContext = any> interface.

In the example below, the country 'United States' and year '2004' are expanded by default. Note that year '2004' is expanded for all countries, not just 'United States'.

Expand / Collapse Groups via API

It is possible to expand and collapse all group rows using the expandAll() and collapseAll() grid API's as shown below:

When more custom behaviour is required, obtain a reference to the rowNode and then call api.setRowNodeExpanded(rowNode, boolean).

For example, to expand a group with the name 'United States' would be done as follows:

api.forEachNode(node => {
     if (node.key === 'United States') {
         api.setRowNodeExpanded(node, true);

The following example demonstrates different ways to expand / collapse row groups via the grid API.

Next Up

Continue to the next section to learn about grouping with Complex Objects.