我有以下情况：
public JsonResult ChangeFilterList(int option)
{
var data = new[] { new { Text = "Unknown option", Value = -1 } };
switch (option)
{
case 2: data = _departmentnameRepository.All.Select(x => new { Text = x.DeptName, Value = x.Id }).ToArray();
break;
case 3: data = Session["projectid"] == null
? _assetSequenceRepository.All.Select(x => new { Text = x.AssetShotName, Value = x.Id }).ToArray()
: _assetSequenceRepository.FindBy(p => p.ProjectId == (int)Session["projectid"]).Select(x => new { Text = x.AssetShotName, Value = x.Id }).ToArray();
break;
default: data = _userRepository.All.Select(x => new { Text = x.DisplayName, Value = x.UserID }).ToArray();
break;
}
return Json(data, JsonRequestBehavior.AllowGet);
}
case2和default看上去很不错，但抱怨的情况下3（有条件）说：Cannot implicitly convert type 'AnonymousType#1[]' to 'AnonymousType#2[]'。?:由于我已经提供了匿名用户的蓝图，因此应该无法确定类型var data = new[] { new { Text = "Unknown option", Value = -1 } };。
解决方案：
@Darin Dimitrov的答案很好，但我想对匿名类型进行一些测试（简单的案例总是需要它）。正如@道格拉斯（Douglas）所怀疑的：我assetSequenceRepository提供的id是long和匿名Value赞成int不提供的long。由于C＃编译器没有隐式转换long为int，所以出现了错误。编译代码段为：
public JsonResult ChangeFilterList(int option = 3)
{
var data = new[] { new { Text = "Unknown option", Value = long.MaxValue } };
switch (option)
{
case 2: data = _departmentnameRepository.All.Select(x => new { Text = x.DeptName, Value = (long)x.Id }).ToArray();
break;
case 3: data = Session["projectid"] == null
? _assetSequenceRepository.All.Select(x => new { Text = x.AssetShotName, Value = x.Id }).ToArray()
: _assetSequenceRepository.FindBy(p => p.ProjectId == (int)Session["projectid"]).Select(x => new { Text = x.AssetShotName, Value = x.Id }).ToArray();
break;
default: data = _userRepository.All.Select(x => new { Text = x.DisplayName, Value = (long)x.UserID }).ToArray();
break;
}
return Json(data, JsonRequestBehavior.AllowGet);
}
我的猜测是，您的FindBy方法返回的对象的属性与您期望的对象具有不同的类型（例如int?而不是int）。尝试指定类型转换，以确保您的匿名类型具有正确的定义：
case 3: data = Session["projectid"] == null
? _assetSequenceRepository.All.Select(x => new { Text = x.AssetShotName, Value = x.Id }).ToArray()
: _assetSequenceRepository.FindBy(p => p.ProjectId == (int)Session["projectid"]).Select(x => new { Text = (string)x.AssetShotName, Value = (int)x.Id }).ToArray();
break;
关键更改是：
new { Text = (string)x.AssetShotName, Value = (int)x.Id })
↖ explicit type casts ↗
本文收集自互联网，转载请注明来源。
如有侵权，请联系 [email protected] 删除。
我来说两句