Get row data in Ext JS 3.0 Grid

I have a grid, which I want to add a button at the top to get the data from a specific column for each r开发者_StackOverflowow selected in the grid. How would I go about doing this?

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Add something like this to the button's click event:

rowsSelected = myGrid.getSelectionModel().getSelections();
for(...){
    aRecord = rowsSelected[i];
    filedValue = aRecord.get('fieldName');
}