c# – 无法使用Entity Framework 6获取存储过程结果

我有一个存储过程,它返回0或1,具体取决于我的数据库中是否存在指定的电子邮件地址：

CREATE PROCEDURE [DatabaseSchema].[EmailAddressIsDuplicate] (@emailAddress nvarchar(255))
AS
BEGIN
    SET NOCOUNT ON;

    IF EXISTS(
        SELECT *
        FROM [DatabaseSchema].[EmailUpdatesRegistrant]
        WHERE EmailAddress = @emailAddress
    )
        RETURN 1
    ELSE
        RETURN 0

    RETURN 0
END

GO

我试图从Entity Framework 6数据库上下文中获取此存储过程的结果：

using (DatabaseContext dbContext = new DatabaseContext())
{
    ObjectParameter param = new ObjectParameter("emailAddress",typeof(bool));
    var result = dbContext.EmailAddressIsDuplicate(emailAddress); 
}

我收到很多错误.

错误#1：使用上面的代码,var结果始终设置为-1.

错误#2：我尝试导航到编辑函数导入并将返回集合设置为布尔标量值.这会引发以下错误：

The data reader returned by the store data provider does not have enough columns for the query requested.

错误#3：我回去并将编辑功能导入返回值设置为无.然后我尝试了以下代码：

using (DatabaseContext dbContext = new DatabaseContext())
{
    var p = new sqlParameter("@emailAddress",emailAddress);
    var result = dbContext.Database.sqlQuery<bool>("DatabaseSchema.EmailAddressIsDuplicate",p);
}

没有立即错误抛出,但我不知道我是否可以从var结果中获取有用的数据.尝试将结果转换为bool会引发以下错误：

Cannot convert type ‘System.Data.Entity.Infrastructure.DbRawsqlQuery’ to ‘bool’

关于如何查看此存储过程(0或1)的结果的任何想法？

解决方法

您可以尝试在存储过程签名中添加输出参数(@result)：

CREATE PROCEDURE [DatabaseSchema].[EmailAddressIsDuplicate]
    (@emailAddress nvarchar(255),@result bit out)
AS
BEGIN
    SET NOCOUNT ON;

    IF EXISTS(SELECT *
              FROM [DatabaseSchema].[EmailUpdatesRegistrant]
              WHERE EmailAddress = @emailAddress)
       SET @result = 1
    ELSE
       SET @result = 0

    RETURN @result
END
GO

(您必须相应地重新定义您的EF模型函数定义)

using (DatabaseContext dbContext = new DatabaseContext())
{
    ObjectParameter isDuplicate = new ObjectParameter("isDuplicate",typeof(bool)); 
    var result = dbContext.EmailAddressIsDuplicate(emailAddress,isDuplicate);

    bool emailIsDuplicate = (bool)isDuplicate.Value;.    
}

如果要使用out参数直接调用存储过程,可以遵循以下建议：
Database.SqlQuery calling stored procedure that has multiple output parameters