实体框架6代码第一个自定义函数 [英] Entity Framework 6 Code First Custom Functions
问题描述
我正在尝试类似的内容:
但是我没有使用EDMX,而只是DbContext和代码。
我遇到过:
< a href =https://codefirstfunctions.codeplex.com/ =nofollow noreferrer> https://codefirstfunctions.codeplex.com/
var locations = context.Locations.Where(e => ; Functions.LatLongDistanceCalc(e.Lat,e.Long,lat,long)> = 10)
它将在SQL Server上调用标量函数(LatLongDistanceCalc)。
有没有什么办法可以不使用EDMX?我知道你可以构造一个手动查询,但是这不会是优先考虑的,因为我希望使用延迟加载代理等恢复实体,以及构建一个更复杂的查询。
您应该可以在 Where
标准中使用标量SQL函数, CodeFirstStoreFunctions
假设您要映射SQL函数[dbo]。[LatLongDistanceCalc]和根据测试套件:
public class MyDataContext:DbContext
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
// ...
modelBuilder.Conventions.Add(new FunctionsConvention(dbo,this.GetType()));
}
//CodeFirstDatabaseSchema是一个约定强制模式名称
//LatLongDistanceCalc是您的函数名称
[DbFunction CodeFirstDatabaseSchema,LatLongDistanceCalc)]
public static int LatLongDistanceCalc(int fromLat,int fromLong,
int toLat,int toLong)
{
//不需要提供实现
抛出新的NotSupportedException();
}
}
的使用将是:
context.Locations
.Where(e => MyDataContext.LatLongDistanceCalc(e.Lat,e.Long,lat,long)> = 10)
I'm trying something similar to this:
How to use scalar-valued function with linq to entity?
However I'm not using EDMX, but instead just DbContext and code first.
I've come across this:
https://codefirstfunctions.codeplex.com/
But the usage isn't suitable. What I am trying to achieve is to be able to do this:
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.
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.
You should be able to use a scalar SQL function in your Where
criterias with CodeFirstStoreFunctions
Assuming you want to map SQL function [dbo].[LatLongDistanceCalc], and according to the test suite:
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:
context.Locations
.Where(e => MyDataContext.LatLongDistanceCalc(e.Lat, e.Long, lat, long) >= 10)
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