实体框架标量函数映射 [英] Entity Framework scalar function mapping

问题描述

 创建功能[dbo]。 @locationId Int 
）
 RETURNS位
 AS 
 BEGIN 
 //代码
 END 
  

我想在Entity Framework上下文中使用它。

我已经在* .edmx文件中添加了：

 < Function Name =CheckLocationReturnType =bitAggregate =falseBuiltIn =falseNiladicFunction = falseIsComposable =trueParameterTypeSemantics =AllowImplicitConversionSchema =dbo> 
< Parameter Name =locationIdType =intMode =In/> 
< / Function> 
  

我还创建了一个使用EdmFunctionAttribute装饰的方法的部分类：

  public partial class MainModelContainer 
 {
 [EdmFunction（MainModel.Store，CheckLocation）] 
 public bool CheckLocation （int locationId）
 {
 throw new NotSupportedException（Direct calls not supported）; 
} 
} 
  

我尝试使用这样的功能： p>

  Context.CheckLocation（locationId）; 
  

并获取NotSupportedException（直接调用不支持）。
它可以在Select方法中运行，但它不适合我。
请帮忙！
如何在没有选择方法的情况下调用此函数？

解决方案

您需要将其作为选择访问

  var students = context.Locations 
 .Select（new {location = CheckLocation（locationId）}）：
  

I have scalar function:

CREATE FUNCTION [dbo].[CheckLocation]
(
    @locationId Int
)
RETURNS bit
AS
BEGIN
    //code
END

I want to use it in Entity Framework context.

I have added this in the *.edmx file:

<Function Name="CheckLocation" ReturnType="bit" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo" >
<Parameter Name="locationId" Type="int" Mode="In" />
</Function>

I have also created a partial class with method decorated with EdmFunctionAttribute:

public partial class MainModelContainer
{
    [EdmFunction("MainModel.Store", "CheckLocation")]
    public bool CheckLocation(int locationId)
    {
        throw new NotSupportedException("Direct calls not supported");
    }
}

I try to use this function like this:

Context.CheckLocation(locationId);

And get NotSupportedException("Direct calls not supported"). It works within Select method, but it does not suit me. Help please! How can I call this function without select method?

解决方案

you need to access it as a select

var students = context.Locations
    .Select ( new  {  location= CheckLocation(locationId)}):

这篇关于实体框架标量函数映射的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！