this.fields.get(...).sortType
我们在用gridPanel的时候，总会用到安某一列排序。如果不指定的话，

... ...
+ "{name: 'budgetName', 'name_cn': '预算单位名称','width':'120', type: 'String',editor:'true',hidden:'false',sum:'false'},"
+ "{name: 'price', 'name_cn': '申请金额','width':'120', type: 'float',editor:'true',hidden:'false',sum:'false'},"
... ...

可能会报下面的错误：‘this.fields.get(...).sortType’为空或不是对象，

这种情况下，给它指定一个排序就ok了

... ...
+ "{name: 'budgetName', 'name_cn': '预算单位名称','width':'120', type: 'String',editor:'true',hidden:'false',sum:'false'},"
+ "{name: 'price', 'name_cn': '申请金额','width':'120', type: 'float',editor:'true',hidden:'false',sum:'false',sort:'true',direction:'ASC'},"
... ...