LINQ to Entity不支持DbGeography条件

Question

I'm using .NET 4.5 and EF 6.0 (also tried with 6.1.3). I have Location geography column in an Entities table ( System.Data.Entity.Spatial.DbGeography ).

using System.Data.Spatial; //also tried Entity one

public class Entity
{
    public DbGeography Location {get;set;}
}

In LINQ I'm trying to select all entities which are inside a specified area.

var center = DbGeography.FromText(string.Format("POINT({0} {1})", latitude, longitude), 4326);
var region = center.Buffer(radius);
var result = db.Entities.Where(x => SqlSpatialFunctions.Filter(x.Location, region) == true).ToArray();

And this query returns me an error:

An unhandled exception of type 'System.NotSupportedException' occurred in EntityFramework.SqlServer.dll

Additional information: The specified type member 'Location' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

In case this is true:

http://referencesource.microsoft.com/#System.Data.Entity/System/Data/Objects/SqlClient/SqlSpatialFunctions.cs

How did this work in examples over the web?

UPD. The same problem using Intersects()

var center = DbGeography.FromText(string.Format("POINT({0} {1})", latitude, longitude), 4326);
var region = center.Buffer(radius);
var result = db.Entities.Where(x => x.Location.Intersects(region) == true).ToArray();

Answer 1

You're likely to get the same, if not better performance using STIntersects() or STWithin() - or their EF equivalent;

// SQL STIntersects() equivalent    
var result = db.Entities.Where(x => x.Intersects(region)).ToArray();

// SQL STWithin() equivalent    
var result = db.Entities.Where(x => x.Intersects(region) == true && x.Difference(region).IsEmpty == true).ToArray();

Use 'Intersects' if you want all Locations which are wholly OR partially in the region. Use 'Within' if you only want those wholly within the region.

Answer 2

如果您使用的是DB First方法，则需要从模型浏览器更新模型，但不能手动更新。

Answer 3

In my case my Linq query would not allow me to use:

x.Intersects(region) == true

I had to change this to

x.Intersects(region).IsTrue