SMART datagrid v.1 > Classes > TreeDataSet

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DataLudi.TreeDataSet.onValueChanging  event

It will be fired just before changing one field value of Row by calling setValue. 

If explicitly return false in this event handler, the value will not be updated. After updating, onValueChanged event will be fired. 

function onValueChanging (ds: TreeDataSet, row: TreeDataRow, field: Integer, value: *): Boolean;
Returns
Boolean
Parameters
ds - TreeDataSet.
row - TreeDataRow.
field - Integer.
value - *.
Code -1
    dataset.onValueChanging = function (ds, row, field, value) {
        if (ds.getFieldName(field) == 'state' && value == 'x') {
            return false;
        }
    };
See Also
onValueChanged
TreeDataRow
Tree Overview
Examples
Tree Data Set
Hello Tree