Ext 表格得到所有行，并得到相应的列值

//取出被所有列值   
function getGridValue(gridname){  
    var grid = Ext.getCmp(gridname);  
      
    var grid_data = grid.getStore();  
    //var data_ids = "";   
    var data_values = "";  
    for(var i= 0 ;i< grid_data.data.length;i++){  
        var row = grid_data.getAt(i);  
        var id = row.get("class_unid");  
        var year = row.get("score");  
        if(year == "") year = "null";  
        data_values += ";"+id+","+year;  
    }  
    data_values = data_values.substring(1);  
      
    return data_values;  
 }