林克不支持的数据类型（地理）
因此，Linq 不支持 Geography 数据类型，这给可爱的“将表格拖到 Linq 设计图面”开发模型的工作带来了很大麻烦。
有什么方法可以扩展 Linq 以使用 Geography 数据类型吗？ 或者，每当我需要使用地理列时，我是否需要构建一个全新的数据层和一组查询？
我已经被这个问题困扰了几天，无法弄清楚是否可能。
So, Linq does not support the Geography data type, which throws a major spanner in the works in the lovely 'drag table onto the Linq design surface' developemnt model.
Is there any way that I can extend Linq to work with the Geography datatype?
Or will I need to build a whole new datalayer and set of queries for whenever I need to use Geography columns?
I've been stuck on this for a few days and can't work out if it's possible.
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将列转换为 varbinary(max)，Linq to SQL可以处理。避免在每个查询中执行此操作的一种方法是添加定义为
CAST(GeographyColumn AS varbinary(max))的计算列。获得
byte[]数据后，您可以编写一个简短的实用方法，使用MemoryStream 将其转换为实际的和Microsoft.SqlServer.Types.SqlGeography类IBinarySerialize.Read/Write方法。据我所知，如果您需要使用任何 CLR 类型（包括地理、几何、hierarchyid 和任何自定义类型），这是唯一可行的解决方案 - Linq 并不“原生”支持其中任何类型。编写所有样板代码有点痛苦，但是您可以通过一些扩展方法使其变得更容易。
您将无法以这种方式查询列；但是，您可以使用 Linq 动态查询库。您不会拥有智能感知或其他一些 Linq 功能，但它仍然是可组合的，因此比手工制作每个查询更好，并且您可以获得强类型结果。
更新：我找到了一个稍微干净的解决方案 这里。您可以这样使用设计器；只需将
SqlGeography包装器属性添加到分部类，并将STGeomFromWKB方法与SqlBytes类一起使用即可。不过，这仍然无法为您提供内联查询功能。Cast the column to a varbinary(max), which Linq to SQL can handle. One way to avoid doing this in every query is just to add a computed column defined as
CAST(GeographyColumn AS varbinary(max)).Once you have the
byte[]data, you can write a short utility method to convert it to the actualMicrosoft.SqlServer.Types.SqlGeographyclass using aMemoryStreamand theIBinarySerialize.Read/Writemethods.As far as I know, this is the only working solution if you need to work with any CLR type, including geography, geometry, hierarchyid, and any custom types - Linq doesn't "natively" support any of them. It's a bit of a pain to write all the boilerplate code, but you can make it easier with a few extension methods.
You won't be able to query against the column this way; however, you can get what I would call halfway there using the Linq Dynamic Query Library. You won't have intellisense or some of the other Linq goodies, but it's still composable and therefore better than hand-crafting every query, and you can get strong-typed results.
Update: I found a slightly cleaner solution here. You can use the designer this way; just add the
SqlGeographywrapper property to a partial class and use theSTGeomFromWKBmethod with theSqlBytesclass. That still won't give you inline query capabilities, though.看起来像您必须自己手动将其映射/解析为您自己的 POCO 类型。
Looks like you'll have to manually map/parse it yourself to your own POCO type.