如何将NULL参数传递给Entity Framework Core 2.1中的上下文查询类型

Question

我正在.NET Core应用程序中处理Entity Framework Core 2.1。我已经编写了存储过程以通过Context Query-Type获取声明列表，该声明采用三个参数，其中两个为可空Guid。只要没有传递空参数，它都能正常工作，但传递空参数，则会引发错误

https://docs.microsoft.com/en-us/ef/core/modeling/query-types

错误

The parameterized query '(@UserVal uniqueidentifier,@ClientVal nvarchar(4000),@Consultati' expects the parameter '@ClientVal', which was not supplied.

EF查询类型

public override IQueryable<GetSystemClaims> Execute()
{
  public Guid UserId { get; set; }
  public Guid? ClientId { get; set; }
  public Guid? ConsultationId { get; set; }


var userParam = new SqlParameter("@UserVal", UserId);
var clientParam = new SqlParameter("@ClientVal", ClientId);
var consultationParam = new SqlParameter("@ConsultationVal", ConsultationId);

        var userClaimsList = Context.Query<UserClaimsQueryView>().FromSql("EXECUTE dbo.ListUserClaims @userId=@UserVal, @clientId=@ClientVal, @consultationId=@ConsultationVal"
            , userParam, clientParam, consultationParam);

        return userClaimsList;
 }

Answer 1

  var userParam = new SqlParameter("@UserVal", UserId);

  var clientParam = new SqlParameter("@ClientVal", SqlDbType.UniqueIdentifier);
  clientParam.Value = (object)ClientId ?? DBNull.Value;

  var consultationParam = new SqlParameter("@ConsultationVal", SqlDbType.UniqueIdentifier);
  consultationParam.Value = (object)ConsultationId ?? DBNull.Value;

  var userClaimsList = Context.Query<UserClaimsQueryView>().FromSql("EXECUTE dbo.ListUserClaims @userId=@UserVal, @clientId=@ClientVal, @consultationId=@ConsultationVal"
            , userParam, clientParam, consultationParam);

Answer 2

您也可以按照以下方式进行操作。

如果您想在值中允许空值，则可以如下所示：

var countryParam = new SqlParameter("@CountryName", searchField.CountryName);
countryParam.Value = (object)searchField.CountryName ?? DBNull.Value;