尝试以通用方式调用方法时出现错误 [英] getting an error on trying to call method in generic way

问题描述

您好，我正在尝试通过将参数传递给如下所示的方法来使用where类过滤表

Hi all I am trying to filter the table using where class by passing parameter to the method like as below,

    private IQueryable<SpaceFunctionType> Get<TEntity>(Expression<Func<TEntity, bool>> predicate) where TEntity : class, ICategorySpaceFunction
    {
        return _dbContext.Set<TEntity>().Where(predicate)
                              .Select(c => new SpaceFunctionType
                              {
                                  Category = c.Category,
                                  SpaceFunction = c.SpaceFunction
                              });
    }

   public IQueryable<SpaceFunctionType> GetSpaceFunctionType(string environmentSource)
   {
        return Get<LibraryEnvironment>(x => x.EnvironmentSource.Name == environmentSource).AsQueryable();
   }

这些是界面详细信息，

public interface ICategorySpaceFunction
{
    public string Category { get; set; }
    public string SpaceFunction { get; set; }
}

这将是类名

public class SpaceFunctionType : ICategorySpaceFunction
{
    public string Category { get; set; }
    public string SpaceFunction { get; set; }
}

但是在这里出现错误Get<LibraryEnvironment>如下所示

but getting an error here Get<LibraryEnvironment> like as below

不能使用类型为"API.DesignHub.Entities.LibraryEnvironment"的类型 作为泛型类型或方法中的类型参数"TEntity" 'Query.Get(Expression>)'.没有 来自的隐式引用转换 "API.DesignHub.Entities.LibraryEnvironment"到 "API.DesignHub.Entities.ICategorySpaceFunction"

The type 'API.DesignHub.Entities.LibraryEnvironment' cannot be used as type parameter 'TEntity' in the generic type or method 'Query.Get(Expression>)'. There is no implicit reference conversion from 'API.DesignHub.Entities.LibraryEnvironment' to 'API.DesignHub.Entities.ICategorySpaceFunction'

我不确定上述方法在哪里出了问题，请问有人可以提出任何对我非常感激的想法，

I am not sure where i am doing wrong with the above method, Could any one please suggest any idea on this that would be very grateful to me,

非常感谢

推荐答案

错误正在发生.但是那里使用的语言有点通用.这意味着LibraryEnvironment没有实现ICategorySpaceFunction. TEntity是ICategorySpaceFunction的一种，您在调用时发送LibraryEnvironment，因此LibraryEnvironment应该与TEntity类似，这是ICategorySpaceFunction的实现，这是一个规则.更多详细信息- https://docs.microsoft.com/zh-CN/dotnet/csharp/programming-guide/generics/constraints-on-type-parameters

The error is what it is happening. But the language used there is a bit generic. What it means is LibraryEnvironment does not implement ICategorySpaceFunction. TEntity is a type of ICategorySpaceFunction and you are sending LibraryEnvironment when calling, so it is a rule that LibraryEnvironment should be similar to TEntity, which is an implementation of ICategorySpaceFunction. more details - https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/generics/constraints-on-type-parameters

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