Linq 当我们连接到MySql时，Any（）方法不起作用_Linq_Entity Framework Core

Linq 当我们连接到MySql时，Any（）方法不起作用

linq entity-framework-core

Linq 当我们连接到MySql时，Any（）方法不起作用,linq,entity-framework-core,Linq,Entity Framework Core,当我们连接到MySql时，调用表上的Any（）方法检查记录是否存在会引发异常，但当我们连接到SqlServer时，它工作正常我正在使用以下代码： public IActionResult GetCustomers() { DbContext db = new DbContext(); if(db.Customers.Any())//here throws an exception when connect to mysql db { //my code }

当我们连接到MySql时，调用表上的Any（）方法检查记录是否存在会引发异常，但当我们连接到SqlServer时，它工作正常我正在使用以下代码：

public IActionResult GetCustomers()
{
   DbContext db = new DbContext();
   if(db.Customers.Any())//here throws an exception when connect to mysql db
   {
     //my code
   }
   return view();
}

我的例外是：

Exception has occurred: CLR/System.InvalidOperationException
An exception of type 'System.InvalidOperationException' occurred in Microsoft.EntityFrameworkCore.dll but was not handled in user code: 'No coercion operator is defined between types 'System.Int16' and 'System.Boolean'.'
   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 System.Linq.Expressions.Expression.Convert(Expression expression, Type type)
   at Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.CreateGetValueExpression(Expression dataReaderExpression, Int32 index, TypeMaterializationInfo materializationInfo, Boolean detailedErrorsEnabled, Boolean box)
   at Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.<>c__DisplayClass13_0.<CreateArrayInitializer>b__0(TypeMaterializationInfo mi, Int32 i)
   at System.Linq.Enumerable.<SelectIterator>d__154`2.MoveNext()
   at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   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.Storage.TypedRelationalValueBufferFactoryFactory.CreateArrayInitializer(CacheKey cacheKey, Boolean detailedErrorsEnabled)
   at Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.<Create>b__11_0(CacheKey k)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.Create(IReadOnlyList`1 types)
   at Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.CreateValueBufferFactory(IRelationalValueBufferFactoryFactory relationalValueBufferFactoryFactory, DbDataReader dataReader)
   at Microsoft.EntityFrameworkCore.Query.Internal.ShaperCommandContext.<NotifyReaderCreated>b__14_0(FactoryAndReader s)
   at Microsoft.EntityFrameworkCore.Internal.NonCapturingLazyInitializer.EnsureInitialized[TParam,TValue](TValue& target, TParam param, Func`2 valueFactory)
   at Microsoft.EntityFrameworkCore.Query.Internal.ShaperCommandContext.NotifyReaderCreated(DbDataReader dataReader)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.BufferlessMoveNext(DbContext _, Boolean buffer)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.QueryMethodProvider.GetResult[TResult](IEnumerable`1 valueBuffers, Boolean throwOnNullResult)
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ResultEnumerable`1.GetEnumerator()
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.MoveNext()
   at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable`1 source, Boolean& found)
   at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass15_1`1.<CompileQueryCore>b__0(QueryContext qc)
   at System.Linq.Queryable.Any[TSource](IQueryable`1 source, Expression`1 predicate)
   at SampleEfCoreLatest.Controllers.HomeController.GetCustomers() in D:\SampleEfCoreLatest\Controllers\HomeController.cs:line 49
   at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.SyncActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionMethodAsync>d__12.MoveNext()

发生异常：CLR/System.InvalidOperationException Microsoft.EntityFrameworkCore.dll中发生类型为“System.InvalidOperationException”的异常，但未在用户代码中处理：“未在类型“System.Int16”和“System.Boolean”之间定义强制运算符。” 位于System.Linq.Expressions.Expression.GetUserDefinedImpressionOrthRow（ExpressionType强制类型，表达式表达式，类型convertToType） at System.Linq.Expressions.Expression.Convert（表达式表达式、类型、方法信息方法） at System.Linq.Expressions.Expression.Convert（表达式表达式，类型）位于Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.CreateGetValueExpression（表达式dataReaderExpression，Int32索引，TypeMaterializationInfo materializationInfo，布尔详细信息ErrorEnabled，布尔框）在Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.c__显示类别13_0.b__0（TypeMaterializationInfo mi，Int32 i）在System.Linq.Enumerable.d_u154`2.MoveNext（）中位于System.Collections.Generic.LargearyBuilder`1.AddRange（IEnumerable`1项） at System.Collections.Generic.EnumerableHelpers.ToArray[T]（IEnumerable`1源） at System.Linq.Enumerable.ToArray[TSource]（IEnumerable`1源）在System.Dynamic.Utils.CollectionExtensions.ToReadOnly[T]（IEnumerable`1可枚举）位于System.Linq.Expressions.Expression.NewArrayInit（类型类型，IEnumerable`1初始值设定项）位于Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.CreateArrayInitializer（CacheKey CacheKey，Boolean DetailedErrorEnabled）位于Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.b__11_0（缓存键k）位于System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd（TKey，Func`2 valueFactory）在Microsoft.EntityFrameworkCore.Storage.TypedRelationalValueBufferFactoryFactory.Create（IReadOnlyList`1类型）中在Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.CreateValueBufferFactory（IRelationalValueBufferFactoryFactory RelationalValueBufferFactory，DbDataReader dataReader）中位于Microsoft.EntityFrameworkCore.Query.Internal.ShaperCommandContext.b_u14_0（FactoryAndReader）在Microsoft.EntityFrameworkCore.Internal.NonCapturingLazyInitializer.EnsureInitialized[TParam，TValue]（TValue和target，TParam参数，Func`2 valueFactory）位于Microsoft.EntityFrameworkCore.Query.Internal.ShaperCommandContext.NotifyReaderCreated（DbDataReader dataReader）位于Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.BufferlessMovenText（DbContext)，布尔缓冲区）在Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext（）中在Microsoft.EntityFrameworkCore.Query.QueryMethodProvider.GetResult[TResult]（IEnumerable`1 valueBuffers，Boolean throwOnNullResult）位于Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ResultEnumerable`1.GetEnumerator（）位于Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.MoveNext（）在System.Linq.Enumerable.TryGetFirst[TSource]（IEnumerable`1 source，Boolean&found）在System.Linq.Enumerable.First[TSource]（IEnumerable`1 source）处在Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.c__显示Class15_1`1.b__0（QueryContext qc） at System.Linq.Queryable.Any[TSource]（IQueryable`1 source，表达式`1谓词）在D:\SampleEfCoreLatest\Controllers\HomeController.cs中的SampleEfCoreLatest.Controllers.HomeController.GetCustomers（）处：第49行位于Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute（对象目标，对象[]参数）位于Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.SyncActionResultExecutor.Execute（IActionResultTypeMapper映射器、ObjectMethodExecutor执行器、对象控制器、对象[]参数）在Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.d_u12.MoveNext（）中

您是否也会得到以下异常：

bool b=dbContext.Customers.Any（）如果您尝试：bool b=dbContext.Customers.Take（1.Count（）！=0
，这实际上是Any（）
所做的，感谢您的回答！dbContext.Customers.Any（i=>i.CustomerId>0）；也会引发相同的异常。为此，我们可以使用bool b=dbContext.Customers.FirstOrDefault（i=>i.CustomerId>0）！=无效的但是我的问题是为什么Any（）不能与mysql一起工作。得到了解决方案我们必须使用Pomelo.EntityFrameworkCore.mysql包而不是mysql.Data.EntityFrameworkCore包您是否也得到了以下例外：bool b=dbContext.Customers.Any（）如果您尝试：bool b=dbContext.Customers.Take（1.Count（）！=0
，这实际上是Any（）
所做的，感谢您的回答！dbContext.Customers.Any（i=>i.CustomerId>0）；也会引发相同的异常。为此，我们可以使用bool b=dbContext.Customers.FirstOrDefault（i=>i.CustomerId>0）！=无效的但是我的问题是为什么Any（）不能与mysql一起工作。找到了解决方案我们必须使用Pomelo.EntityFrameworkCore.mysql包而不是mysql.Data.EntityFrameworkCore包