Data Grid columns are updated when the columns
attribute itself is set. So you can tell Anvil to update the columns by doing:
self.data_grid_1.columns = self.data_grid_1.columns
So this is one way to change a column’s width:
self.data_grid_1.columns[0]['width'] = 500
self.data_grid_1.columns = self.data_grid_1.columns
(Thinks: I should add this to the reference docs…)