easyui datagrid 动态生成列

easyui datagrid 定义列的方式通常是：

$('#grid').datagrid({columns:[[  
    {field:'f1',title:'字段1',width:160},  
    {field:'f2',title:'字段2',width:160}  
]]});

但在实际项目中，我们会经常需要datagrid能动态生成列。

以下是datagrid一种动态列的实现方式：

var options={};  
$(function(){  
    var myNj = 9;  
    //初始化  
    $("#disgrid").datagrid({  
        type: 'POST',  
        nowrap: false,  
        striped: true,  
        fit:true,  
        width:1024,  
        height:500,  
        url:'',  
        pageSize:30,  
        remoteSort: false,  
        pagination:true,  
        rownumbers:true,  
        singleSelect:true,  
        queryParams:{  
            nj:myNj,  
            unitType:1  
        }  
    });   
      
    fetchData(myNj);  
});  
  
function fetchData(nj) {  
    var s = "";  
    s = "[[";  
    s = s + "{field:'unitname',title:'单元',width:160},{field:'practicetime',title:'测试时间',width:160},{field:'userid',title:'userid',width:120,hidden:'true'},{field:'serial',title:'serial',width:120,hidden:'true'},{field:'unitid',title:'unitid',width:100,hidden:'true'},";  
      
    //lu todo 列的定义可从服务器获得  
    if (nj==9) {  
        s = s + "{field:'aipanel_text_exam',title:'短文朗读',width:80},{field:'aipanel_scene_exam',title:'情景对话',width:80},{field:'aipanel_oral_exam',title:'简短说话',width:80}";  
  
        //lu 加一个计算列  
        s = s + ",{field:'tatal_score',title:'总分',width:60,formatter:function(value,rec){return paraseIntValue(rec.aipanel_text_exam)+paraseIntValue(rec.aipanel_scene_exam)+paraseIntValue(rec.aipanel_oral_exam);}}";  
    }else if (nj==7||nj==8){  
      //....  
  }  
    s = s + "]]";  
    options={};  
    options.url = '/app/search.do';  
    options.queryParams = {  
        nj:nj,  
        unitType:1  
    };  
    options.columns = eval(s);  
    //lu 增加一列  
    options.columns[0].push(  
        {  
            field:'desc',title:'查看详情',width:60,  
            formatter:function(value,rec){  
                return "<a href=\"javascript:showDescInfo(\'"+rec.serial+"\',\'"+rec.scene_score+"\',\'"+rec.total_score+"\');\">详情</a>";  
            }  
        }     
    );  
      
    $('#disgrid').datagrid(options);  
    $('#disgrid').datagrid('reload');     
      
}