实体框架6代码优先自定义函数

I'm trying something similar to this:

我正在尝试类似的东西：

How to use scalar-valued function with linq to entity?

如何使用带有linq的标量值函数实体？

However I'm not using EDMX, but instead just DbContext and code first.

但是我没有使用EDMX，而是先使用DbContext和代码。

I've come across this:

我遇到过这个：

https://codefirstfunctions.codeplex.com/

But the usage isn't suitable. What I am trying to achieve is to be able to do this:

但用法并不合适。我想要实现的是能够做到这一点：

var locations = context.Locations.Where(e => Functions.LatLongDistanceCalc(e.Lat, e.Long, lat, long) >= 10)

Where it will call a scalar function (LatLongDistanceCalc) on SQL Server.

它将在SQL Server上调用标量函数（LatLongDistanceCalc）。

Is there any way to do this without using EDMX? I know that you can construct a manual query but this wouldn't be prefereable because I want to bring back entities with lazy loading proxies etc as well as building up a more complex query.

没有使用EDMX有没有办法做到这一点？我知道你可以构建一个手动查询，但这不会是优先的，因为我想带回具有延迟加载代理等的实体以及构建更复杂的查询。

1 个解决方案

#1

You should be able to use a scalar SQL function in your Where criterias with CodeFirstStoreFunctions

您应该能够在CodeFirstStoreFunctions的Where标准中使用标量SQL函数

Assuming you want to map SQL function [dbo].[LatLongDistanceCalc], and according to the test suite:

假设您要映射SQL函数[dbo]。[LatLongDistanceCalc]，并根据测试套件：

public class MyDataContext: DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
       //...

       modelBuilder.Conventions.Add(new FunctionsConvention("dbo", this.GetType()));
    }

    // "CodeFirstDatabaseSchema" is a convention mandatory schema name
    // "LatLongDistanceCalc" is the name of your function

    [DbFunction("CodeFirstDatabaseSchema", "LatLongDistanceCalc")]
    public static int LatLongDistanceCalc(int fromLat, int fromLong,
                                                       int toLat, int toLong)
    {
       // no need to provide an implementation
       throw new NotSupportedException();
    }
}

usage would then be:

那么用法是：

context.Locations
       .Where(e => MyDataContext.LatLongDistanceCalc(e.Lat, e.Long, lat, long) >= 10)

#1