jQuery EasyUI DataGrid Checkbox 数据设定与取值

$('#dg').datagrid({
    title: 'CheckBox Selection on DataGrid',
    url: 'datagrid_data3.json',
    width: '700',
    rownumbers: true,
    columns:[[
        { field:'ck',checkbox:true }, 
        { field: 'productid', title: 'productid' },
        { field: 'productname', title: 'productname' },
        { field: 'unitcost', title: 'unitcost' },
        { field: 'status', title: 'status' },
        { field: 'listprice', title: 'listprice' },
        { field: 'itemid', title: 'itemid' }
    ]],
    singleSelect: false,
    selectOnCheck: true,
    checkOnSelect: true,
    onLoadSuccess:function(data){                    
        if(data){
            $.each(data.rows, function(index, item){
                if(item.checked){
                    $('#dg').datagrid('checkRow', index);
                }
            });
        }
    }                 
});
 
$('#ButonGetCheck').click(function(){
    var checkedItems = $('#dg').datagrid('getChecked');
    var names = [];
    $.each(checkedItems, function(index, item){
        names.push(item.productname);
    });                
    console.log(names.join(","));
});

$(function(){
    $('#dg').datagrid({
        title: 'CheckBox Selection on DataGrid',
        url: 'datagrid_data3.json',
        width: '700',
        rownumbers: true,
        columns:[[
            {field:'checked',formatter:function(value,row,index){ 
                if(row.checked){
                    return '<input type="checkbox" name="DataGridCheckbox" checked="checked">'; 
                }
                else{
                    return '<input type="checkbox" name="DataGridCheckbox">'; 
                }
            }}, 
            { field: 'productid', title: 'productid' },
            { field: 'productname', title: 'productname' },
            { field: 'unitcost', title: 'unitcost' },
            { field: 'status', title: 'status' },
            { field: 'listprice', title: 'listprice' },
            { field: 'itemid', title: 'itemid' }
        ]],
        singleSelect: true
    });
    
    $('#ButonGetCheck').click(function(){
        var checkedItems = $('#dg').datagrid('getChecked');
        var names = [];
        $.each(checkedItems, function(index, item){
            names.push(item.productname);
        });                
        console.log(names.join(","));
    });
});
 
$.extend($.fn.datagrid.methods, {
    getChecked: function (jq) {
        var rr = [];
        var rows = jq.datagrid('getRows');
        jq.datagrid('getPanel').find('div.datagrid-cell input:checked').each(function () {
            var index = $(this).parents('tr:first').attr('datagrid-row-index');
            rr.push(rows[index]);
        });
        return rr;
    }
});