Question

我已经开始使用EF核心使用cosmosDB.Sql。我有一个简单的模型

public class Transaction 
    {

        public Guid id { get; set; }

        public DateTime StartTime { get; set; }

        public string Property1 { get; set; }

        public Status Status { get; set; }
}

public enum Status
    {

        NotInitiated = 1,

        InProgress = 2,

        Completed = 3
    }

我正在使用 Microsoft.EntityFrameworkCore.Cosmos.Sql：2.2.0-preview1-35029 Microsoft.EntityFrameworkCore：2.2.0-preview1-35029 （和其他相关的）nuget包

我能够将Transaction对象保存到cosmosdb集合中

//来自集合的json样本

{
    "id": "20acc26b-ce07-4807-b630-91acf78e29d1",
    "StartTime ": "0001-01-01T00:00:00",
    "Property1 ": "value",
    "Discriminator": "Transaction",
    "Status": 1,
    "_rid": ",
    "_self": "",
    "_etag": "",
    "_attachments": "attachments/",
    "_ts": ....
}

//结束

但是当我尝试使用以下语法使用cosmosdb上下文获取Transaction对象时

this.context.Transaction.Where(x => x.id == id).FirstOrDefault();

我得到了例外。

``` 异常消息：

No coercion operator is defined between types 'Newtonsoft.Json.Linq.JToken' and 'Status'(EnumType).

堆栈跟踪：

at System.Linq.Expressions.Expression.GetUserDefinedCoercionOrThrow(ExpressionType coercionType, Expression expression, Type convertToType)
   at System.Linq.Expressions.Expression.Convert(Expression expression, Type type, MethodInfo method)
   at Microsoft.EntityFrameworkCore.Cosmos.Sql.Query.Internal.ValueBufferFactoryFactory.CreateGetValueExpression(Expression jObjectExpression, IProperty property)
   at System.Linq.Enumerable.SelectEnumerableIterator`2.ToArray()
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at System.Dynamic.Utils.CollectionExtensions.ToReadOnly[T](IEnumerable`1 enumerable)
   at System.Linq.Expressions.Expression.NewArrayInit(Type type, IEnumerable`1 initializers)
   at Microsoft.EntityFrameworkCore.Cosmos.Sql.Query.Internal.ValueBufferFactoryFactory.Create(IEntityType entityType)
   at Microsoft.EntityFrameworkCore.Cosmos.Sql.Query.Internal.EntityShaper.CreateShaperLambda()
   at Microsoft.EntityFrameworkCore.Cosmos.Sql.Query.Expressions.Internal.QueryShaperExpression.Reduce()
   at System.Linq.Expressions.Expression.ReduceAndCheck()
   at System.Linq.Expressions.Expression.ReduceExtensions()
   at System.Linq.Expressions.Compiler.StackSpiller.RewriteExtensionExpression(Expression expr, Stack stack)
   at System.Linq.Expressions.Compiler.StackSpiller.RewriteExpression(Expression node, Stack stack)
   at System.Linq.Expressions.Compiler.StackSpiller.ChildRewriter.Add(Expression expression)
   at System.Linq.Expressions.Compiler.StackSpiller.ChildRewriter.AddArguments(IArgumentProvider expressions)
   at System.Linq.Expressions.Compiler.StackSpiller.RewriteMethodCallExpression(Expression expr, Stack stack)
   at System.Linq.Expressions.Compiler.StackSpiller.RewriteExpression(Expression node, Stack stack)
   at System.Linq.Expressions.Compiler.StackSpiller.ChildRewriter.Add(Expression expression)
   at System.Linq.Expressions.Compiler.StackSpiller.ChildRewriter.AddArguments(IArgumentProvider expressions)
   at System.Linq.Expressions.Compiler.StackSpiller.RewriteMethodCallExpression(Expression expr, Stack stack)
   at System.Linq.Expressions.Compiler.StackSpiller.RewriteExpression(Expression node, Stack stack)
   at System.Linq.Expressions.Compiler.StackSpiller.RewriteExpressionFreeTemps(Expression expression, Stack stack)
   at System.Linq.Expressions.Compiler.StackSpiller.Rewrite[T](Expression`1 lambda)
   at System.Linq.Expressions.Expression`1.Accept(StackSpiller spiller)
   at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda)
   at System.Linq.Expressions.Expression`1.Compile(Boolean preferInterpretation)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateExecutorLambda[TResults]()
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateQueryExecutor[TResult](QueryModel queryModel)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](Expression query, IQueryModelGenerator queryModelGenerator, IDatabase database, IDiagnosticsLogger`1 logger, Type contextType)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass13_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Remotion.Linq.QueryableBase`1.GetEnumerator()
   at System.Collections.Generic.List`1.AddEnumerable(IEnumerable`1 enumerable)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at WK.Drago.WebApi.Controllers.CosmosDBController.Get(Guid transactionId) in D:\SourceCode\Development\Drago\WK.Drago.WebApi\Controllers\CosmosDBController.cs:line 37
   at lambda_method(Closure , Object )
   at Microsoft.Extensions.Internal.ObjectMethodExecutorAwaitable.Awaiter.GetResult()
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.TaskOfActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextExceptionFilterAsync()

Cosmos.Sql：类型'Newtonsoft.Json.Linq.JToken'和'Status'（EnumType）之间未定义强制运算符

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