Assigning the DataSource instance to Grid widget's dataSource field is not supported and will not work as expected. It is preferable to assign the DataSource during the databound widget declaration, or in cases where changing the DataSource is required, you may use setDataSource method of the widget. This way the widget will be able to attached to DataSource's notification events and correctly refresh its state when needed.
Also note that calling read method of the DataSource is sufficient in order to repopulate the DataSource (which will automatically refresh the widget's content).
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