Question

这是我的EF查询。

抛出例：无法比较类型'System.Collections.Generic.List`1 [[System.String，mscorlib，Version = 4.0.0.0，Culture = neutral，PublicKeyToken = b77a5c561934e089]]'的元素。仅原始类型，枚举

所有参数已满。

    public List<User> GetLawyersData(List<Guid> IdList, List<string> selectedCountries, List<string> selectedCities, List<string> selectedDistricts, List<string> selectedOccupations, List<string> selectedProfessions)
    {

        var result = (from u in _userDbContext
                      join ui in _userInformationDbContext
                      on u.Id equals ui.UserID
                      join d in _districtDbContext
                      on ui.DistrictId equals d.Id
                      join c in _cityDbContext
                      on d.CityID equals c.Id
                      join co in _countryDbContext
                      on c.CountryID equals co.Id
                      join uo in _userOccupationInformationDbContext
                      on u.Id equals uo.UserID
                      join oc in _occupationDbContext
                      on uo.OccupationID equals oc.Id
                      join up in _userProfessionDbContext
                      on u.Id equals up.UserID
                      join pr in _professionDbContext
                      on up.ProfessionID equals pr.Id
                      where IdList.Contains(u.Id) &&
                      (selectedCountries != null && selectedCountries.Count > 0 ? selectedCountries.Contains(co.AutoId.ToString()) : true) && (selectedCities != null && selectedCities.Count > 0 ? selectedCities.Contains(c.AutoId.ToString()) : true)
                      && (selectedDistricts != null && selectedDistricts.Count > 0 ?  selectedDistricts.Contains(d.AutoId.ToString()) : true)
                      && (selectedOccupations != null && selectedOccupations.Count > 0 ? selectedOccupations.Contains(oc.AutoId.ToString()) : true)
                      && (selectedProfessions != null && selectedProfessions.Count > 0 ? selectedProfessions.Contains(pr.AutoId.ToString()) : true)
                      select u).ToList();

        return result;

我该怎么办？

Answer 1

我认为，问题在于在linq查询中使用ToString（）函数。在反序列化之前，不能在字段上使用toString（）。因此，与其尝试在查询中调用ToString（），不如在事后对结果进行操作或比较确切的数据类型值。

数据库中没有ToString（）操作的概念，这就是为什么您会出错。

无法比较类型为'System.Collections.Generic.List`1 [[System.String，mscorlib]]'的元素。仅原始类型，枚举

1 个答案: