entity-framework - 首先使用实体​​框架代码映射 SqlGeography

Question

我正在玩 Entity Framework 4 和sqlgeography数据类型。我无法让实体框架将我的 sqlgeography 类型映射到数据库。我已将我的类定义为 POCO，并希望实体框架为我创建表。我没有成功，然后尝试自己创建表格也没有成功。

我的课看起来像这样：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Microsoft.SqlServer.Server;
using Microsoft.SqlServer.Types;

namespace Nearest.Models
{
    public class Point
    {
        public int Id { get; set; }
        public int DataSet { get; set; }
        public int Author { get; set; }
        public SqlGeography Geo { get; set; }
        public string Data { get; set; }
    }
}

这是我得到的错误：

<Exception xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<ExceptionType>System.InvalidOperationException</ExceptionType>
<Message>
An error occurred when trying to create a controller of type 'Nearest.Controllers.PointsController'. Make sure that the controller has a parameterless public constructor.
</Message>
<StackTrace>
at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpControllerContext controllerContext, Type controllerType) at System.Web.Http.Dispatcher.DefaultHttpControllerFactory.CreateInstance(HttpControllerContext controllerContext, HttpControllerDescriptor controllerDescriptor) at System.Web.Http.Dispatcher.DefaultHttpControllerFactory.CreateController(HttpControllerContext controllerContext, String controllerName) at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncInternal(HttpRequestMessage request, CancellationToken cancellationToken) at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
</StackTrace>
<InnerException>
<ExceptionType>System.TypeInitializationException</ExceptionType>
<Message>
The type initializer for 'Nearest.Controllers.PointsController' threw an exception.
</Message>
<StackTrace>
at Nearest.Controllers.PointsController..ctor() at lambda_method(Closure ) at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpControllerContext controllerContext, Type controllerType)
</StackTrace>
<InnerException>
<ExceptionType>System.Data.DataException</ExceptionType>
<Message>
An exception occurred while initializing the database. See the InnerException for details.
</Message>
<StackTrace>
at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action) at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() at System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c) at System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input) at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action) at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase() at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() at System.Data.Entity.Internal.Linq.InternalSet`1.GetEnumerator() at System.Data.Entity.Infrastructure.DbQuery`1.System.Collections.Generic.IEnumerable<TResult>.GetEnumerator() at System.Linq.Enumerable.Count[TSource](IEnumerable`1 source) at Nearest.Models.PointRepository..ctor() in C:\Projects\Nearest\trunk\Nearest\Models\PointRepository.cs:line 15 at Nearest.Controllers.PointsController..cctor() in C:\Projects\Nearest\trunk\Nearest\Controllers\PointsController.cs:line 14
</StackTrace>
<InnerException>
<ExceptionType>System.Data.EntityCommandCompilationException</ExceptionType>
<Message>
An error occurred while preparing the command definition. See the inner exception for details.
</Message>
<StackTrace>
at System.Data.EntityClient.EntityCommandDefinition..ctor(DbProviderFactory storeProviderFactory, DbCommandTree commandTree) at System.Data.EntityClient.EntityProviderServices.CreateCommandDefinition(DbProviderFactory storeProviderFactory, DbCommandTree commandTree) at System.Data.EntityClient.EntityProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree) at System.Data.Common.DbProviderServices.CreateCommandDefinition(DbCommandTree commandTree) at System.Data.Objects.Internal.ObjectQueryExecutionPlan.Prepare(ObjectContext context, DbQueryCommandTree tree, Type elementType, MergeOption mergeOption, Span span, ReadOnlyCollection`1 compiledQueryParameters) at System.Data.Objects.ELinq.ELinqQueryState.GetExecutionPlan(Nullable`1 forMergeOption) at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source) at System.Data.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__1[TResult](IEnumerable`1 sequence) at System.Data.Objects.ELinq.ObjectQueryProvider.ExecuteSingle[TResult](IEnumerable`1 query, Expression queryRoot) at System.Data.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute[S](Expression expression) at System.Data.Entity.Internal.Linq.DbQueryProvider.Execute[TResult](Expression expression) at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source) at System.Data.Entity.Internal.InternalContext.QueryForModelHash() at System.Data.Entity.Internal.InternalContext.CompatibleWithModel(Boolean throwIfNoMetadata) at System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context) at System.Data.Entity.Internal.InternalContext.<>c__DisplayClass5.<PerformDatabaseInitialization>b__3() at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
</StackTrace>
<InnerException>
<ExceptionType>System.Data.MappingException</ExceptionType>
<Message>
(6,10) : error 3004: Problem in mapping fragments starting at line 6:No mapping specified for properties Point.Geo in Set Points. An Entity with Key (PK) will not round-trip when: Entity is type [Nearest.Models.Point]
</Message>
<StackTrace>
at System.Data.Mapping.StorageMappingItemCollection.ViewDictionary.SerializedGenerateViews(EntityContainer container, Dictionary`2 resultDictionary) at System.Data.Mapping.StorageMappingItemCollection.ViewDictionary.SerializedGetGeneratedViews(EntityContainer container) at System.Data.Common.Utils.Memoizer`2.<>c__DisplayClass2.<Evaluate>b__0() at System.Data.Common.Utils.Memoizer`2.Result.GetValue() at System.Data.Common.Utils.Memoizer`2.Evaluate(TArg arg) at System.Data.Mapping.StorageMappingItemCollection.ViewDictionary.GetGeneratedView(EntitySetBase extent, MetadataWorkspace workspace, StorageMappingItemCollection storageMappingItemCollection) at System.Data.Metadata.Edm.MetadataWorkspace.GetGeneratedView(EntitySetBase extent) at System.Data.Query.PlanCompiler.PreProcessor.ExpandView(Node node, ScanTableOp scanTableOp, IsOfOp& typeFilter) at System.Data.Query.PlanCompiler.PreProcessor.ProcessScanTable(Node scanTableNode, ScanTableOp scanTableOp, IsOfOp& typeFilter) at System.Data.Query.PlanCompiler.PreProcessor.Visit(ScanTableOp op, Node n) at System.Data.Query.InternalTrees.ScanTableOp.Accept[TResultType](BasicOpVisitorOfT`1 v, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.VisitNode(Node n) at System.Data.Query.PlanCompiler.SubqueryTrackingVisitor.VisitChildren(Node n) at System.Data.Query.PlanCompiler.SubqueryTrackingVisitor.VisitRelOpDefault(RelOp op, Node n) at System.Data.Query.PlanCompiler.PreProcessor.Visit(ProjectOp op, Node n) at System.Data.Query.InternalTrees.ProjectOp.Accept[TResultType](BasicOpVisitorOfT`1 v, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.VisitNode(Node n) at System.Data.Query.PlanCompiler.SubqueryTrackingVisitor.VisitChildren(Node n) at System.Data.Query.PlanCompiler.SubqueryTrackingVisitor.VisitRelOpDefault(RelOp op, Node n) at System.Data.Query.PlanCompiler.PreProcessor.Visit(ProjectOp op, Node n) at System.Data.Query.InternalTrees.ProjectOp.Accept[TResultType](BasicOpVisitorOfT`1 v, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.VisitNode(Node n) at System.Data.Query.PlanCompiler.SubqueryTrackingVisitor.VisitChildren(Node n) at System.Data.Query.PlanCompiler.SubqueryTrackingVisitor.VisitRelOpDefault(RelOp op, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.VisitSortOp(SortBaseOp op, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.Visit(ConstrainedSortOp op, Node n) at System.Data.Query.InternalTrees.ConstrainedSortOp.Accept[TResultType](BasicOpVisitorOfT`1 v, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.VisitNode(Node n) at System.Data.Query.PlanCompiler.SubqueryTrackingVisitor.VisitChildren(Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfNode.VisitDefault(Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfNode.VisitPhysicalOpDefault(PhysicalOp op, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.Visit(PhysicalProjectOp op, Node n) at System.Data.Query.InternalTrees.PhysicalProjectOp.Accept[TResultType](BasicOpVisitorOfT`1 v, Node n) at System.Data.Query.InternalTrees.BasicOpVisitorOfT`1.VisitNode(Node n) at System.Data.Query.PlanCompiler.PreProcessor.Process() at System.Data.Query.PlanCompiler.PreProcessor.Process(PlanCompiler planCompilerState, StructuredTypeInfo& typeInfo) at System.Data.Query.PlanCompiler.PlanCompiler.Compile(List`1& providerCommands, ColumnMap& resultColumnMap, Int32& columnCount, Set`1& entitySets) at System.Data.EntityClient.EntityCommandDefinition..ctor(DbProviderFactory storeProviderFactory, DbCommandTree commandTree)
</StackTrace>
</InnerException>
</InnerException>
</InnerException>
</InnerException>
</Exception>

Answer 1

As far as I know, EF4 doesn't yet support the Geography and Geometry datatypes of SQL Server 2008. This will be a feature of Entity Framework v5 -- to be released with .NET 4.5 later this year).

See a EF5 Spatial Types Walkthrough for an explanation of how EF5 will support spatial types.

And see this blog post by EF goddess Julie Lerman on how to still use geography types with EF4 - with a bit of extra work - not sure how much of that works in EF code-first, though.

Also: see this other SO post on the topic