bootstrap select下拉框验证

pollutant_source_type: {
validators: {
notEmpty: {
message: ‘类型不能为空’
},
callback: {
message: ‘请选择类型’,
callback: function (value, validator) {
if (value =="") { //""是–请选择–选项
return false;
} else {
return true;
}
}
}
}
},