C# 加载相关对象时发生异常。实体框架

在数据库中加载相关对象时出现异常。我正在加载我所有的

MatchData

对象，我想用foreach迭代它们

我正在加载的对象是：

匹配数据类：

public class MatchData
{
    [Key]
    public virtual int Id { get; set; }
    private List<PlayerData> blueTeam = new List<PlayerData>();
    private List<PlayerData> redTeam = new List<PlayerData>();

    [InverseProperty("MatchDataBlue")]
    public virtual List<PlayerData> BlueTeam
    {
        get { return blueTeam; }
        set { blueTeam = value; }
    }
    [InverseProperty("MatchDataRed")]
    public virtual List<PlayerData> RedTeam
    {
        get { return redTeam; }
        set { redTeam = value; }
    }
}

public class PlayerData
{

    // properties
    [Key]
    public virtual int Id { get; set; }

    public virtual Player Player { get; set; }
    public virtual MatchData MatchDataBlue { get; set; }
    public virtual MatchData MatchDataRed { get; set; }
}

下面是我如何加载MatchData对象的方法：

using (DBBooneContext db = new DBBooneContext())
{
    var smth = db.MatchData
        .Include(md => md.BlueTeam)
        .ToList();
}

DBContext

class DBBooneContext : DbContext
{
    public DbSet<Player> Player { get; set; }
    public DbSet<PlayerData> PlayerData { get; set; }
    public DbSet<MatchData> MatchData { get; set; }
}

classdbboonecontext:DbContext
{
公共DbSet播放器{get；set；}
公共DbSet PlayerData{get；set；}
公共数据库集匹配数据{get；set；}
}

当我运行ToList时，我得到一个异常： EntityFramework.SqlServer.dll中发生类型为“System.Reflection.TargetInvocationException”的未处理异常

完全例外：

A first chance exception of type 'System.Reflection.TargetInvocationException' occurred in EntityFramework.SqlServer.dll
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.InvalidOperationException: The class 'Boonekamp.ClassCollection.PlayerData' has no parameterless constructor.
   at System.Data.Entity.Core.Objects.DelegateFactory.GetConstructorForType(Type type)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Emit_ConstructEntity(EntityType oSpaceType, IEnumerable`1 propertyBindings, Expression entityKeyReader, Expression entitySetReader, TranslatorArg arg, EntityProxyTypeInfo proxyTypeInfo)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visit(EntityColumnMap columnMap, TranslatorArg arg)
   at System.Data.Entity.Core.Query.InternalTrees.EntityColumnMap.Accept[TResultType,TArgType](ColumnMapVisitorWithResults`2 visitor, TArgType arg)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.HandleSpandexRecord(RecordColumnMap columnMap, TranslatorArg arg, RowType spanRowType)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visit(RecordColumnMap columnMap, TranslatorArg arg)
   at System.Data.Entity.Core.Query.InternalTrees.RecordColumnMap.Accept[TResultType,TArgType](ColumnMapVisitorWithResults`2 visitor, TArgType arg)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.ProcessCollectionColumnMap(CollectionColumnMap columnMap, TranslatorArg arg, ColumnMap discriminatorColumnMap, Object discriminatorValue)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visit(DiscriminatedCollectionColumnMap columnMap, TranslatorArg arg)
   at System.Data.Entity.Core.Query.InternalTrees.DiscriminatedCollectionColumnMap.Accept[TResultType,TArgType](ColumnMapVisitorWithResults`2 visitor, TArgType arg)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.AcceptWithMappedType(TranslatorVisitor translatorVisitor, ColumnMap columnMap)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.HandleSpandexRecord(RecordColumnMap columnMap, TranslatorArg arg, RowType spanRowType)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visit(RecordColumnMap columnMap, TranslatorArg arg)
   at System.Data.Entity.Core.Query.InternalTrees.RecordColumnMap.Accept[TResultType,TArgType](ColumnMapVisitorWithResults`2 visitor, TArgType arg)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.ProcessCollectionColumnMap(CollectionColumnMap columnMap, TranslatorArg arg, ColumnMap discriminatorColumnMap, Object discriminatorValue)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.ProcessCollectionColumnMap(CollectionColumnMap columnMap, TranslatorArg arg)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visit(SimpleCollectionColumnMap columnMap, TranslatorArg arg)
   at System.Data.Entity.Core.Query.InternalTrees.SimpleCollectionColumnMap.Accept[TResultType,TArgType](ColumnMapVisitorWithResults`2 visitor, TArgType arg)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap[T](ColumnMap columnMap, MetadataWorkspace workspace, SpanIndex spanIndex, MergeOption mergeOption, Boolean streaming, Boolean valueLayer)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
   at System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap(Translator translator, Type elementType, ColumnMap columnMap, MetadataWorkspace workspace, SpanIndex spanIndex, MergeOption mergeOption, Boolean streaming, Boolean valueLayer)
   at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlanFactory.Prepare(ObjectContext context, DbQueryCommandTree tree, Type elementType, MergeOption mergeOption, Boolean streaming, Span span, IEnumerable`1 compiledQueryParameters, AliasGenerator aliasGenerator)
   at System.Data.Entity.Core.Objects.EntitySqlQueryState.GetExecutionPlan(Nullable`1 forMergeOption)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__6()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__5()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
   at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Boonekamp.ClassCollection.Player.getStats(Predicate`1 predicate) in d:\Dropbox\code\c#\Boonekamp\Boonekamp\ClassCollection\Player.cs:line 49

Additional information: Exception has been thrown by the target of an invocation.

EntityFramework.SqlServer.dll中发生了类型为“System.Reflection.TargetInvocationException”的首次意外异常
System.Reflection.TargetInvocationException:调用的目标已引发异常。-->System.InvalidOperationException:类“Boonekamp.ClassCollection.PlayerData”没有无参数构造函数。
位于System.Data.Entity.Core.Objects.DelegateFactory.GetConstructorForType（类型）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Emit_ConstructEntity（EntityType-oSpaceType，IEnumerable`1 propertyBindings，Expression entityKeyReader，Expression entitySetReader，TranslatorArg，EntityProxyTypeInfo）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visite（EntityColumnMap columnMap，TranslatorArg arg）
在System.Data.Entity.Core.Query.InternalTrees.EntityColumnMap.Accept[TResultType，TArgType]（ColumnMapVisitorWithResults`2访问者，TArgType arg）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.HandleSpandexRecord（RecordColumnMap columnMap，TranslatorArg arg，RowType spanRowType）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visite（RecordColumnMap columnMap，TranslatorArg arg）
位于System.Data.Entity.Core.Query.InternalTrees.RecordColumnMap.Accept[TResultType，TArgType]（ColumnMapVisitorWithResults`2访问者，TArgType参数）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.ProcessCollectionColumnMap（CollectionColumnMap columnMap、TranslatorArg arg、columnMap discriminatorColumnMap、Object discriminatorValue）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visite（DiscriminatedCollectionColumnMap columnMap，TranslatorArg arg）
位于System.Data.Entity.Core.Query.InternalTrees.DiscriminatedCollectionColumnMap.Accept[TResultType，TargetType]（ColumnMapVisitorWithResults`2访问者，TargetType参数）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.AcceptWithMappedType（TranslatorVisitor TranslatorVisitor，ColumnMap ColumnMap）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.HandleSpandexRecord（RecordColumnMap columnMap，TranslatorArg arg，RowType spanRowType）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visite（RecordColumnMap columnMap，TranslatorArg arg）
位于System.Data.Entity.Core.Query.InternalTrees.RecordColumnMap.Accept[TResultType，TArgType]（ColumnMapVisitorWithResults`2访问者，TArgType参数）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.ProcessCollectionColumnMap（CollectionColumnMap columnMap、TranslatorArg arg、columnMap discriminatorColumnMap、Object discriminatorValue）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.ProcessCollectionColumnMap（CollectionColumnMap columnMap，TranslatorArg arg）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslatorVisitor.Visite（SimpleCollectionColumnMap columnMap，TranslatorArg arg）
在System.Data.Entity.Core.Query.InternalTrees.SimpleCollectionColumnMap.Accept[TResultType，TargetType]（ColumnMapVisitorWithResults`2访问者，TargetType arg）
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap[T]（ColumnMap ColumnMap，MetadataWorkspace工作区，SpanIndex SpanIndex，MergeOption MergeOption，Boolean streaming，Boolean valueLayer）
---内部异常堆栈跟踪的结束---
位于System.RuntimeMethodHandle.InvokeMethod（对象目标、对象[]参数、签名符号、布尔构造函数）
位于System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal（对象obj，对象[]参数，对象[]参数）
在System.Reflection.RuntimeMethodInfo.Invoke（对象obj、BindingFlags invokeAttr、绑定器绑定器、对象[]参数、CultureInfo区域性）
在System.Reflection.MethodBase.Invoke（对象obj，对象[]参数）处
位于System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap（Translator-Translator，Type elementType，ColumnMap ColumnMap，MetadataWorkspace，SpanIndex SpanIndex，MergeOption MergeOption，Boolean streaming，Boolean valueLayer）
在System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlanFactory.Prepare（ObjectContext上下文、DbQueryCommandTree树、类型elementType、MergeOption MergeOption、布尔流、跨度、IEnumerable`1 compiledQueryParameters、别名生成器AliasGenerator）
位于System.Data.Entity.Core.Objects.EntitySqlQueryState.GetExecutionPlan（可为null的`1 forMergeOption）
在System.Data.Entity.Core.Objects.ObjectQuery`1.c_u DisplayClass7.b__u6（）
在System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T]（Func`1 Func，IDBEcutionStrategy executionStrategy，Boolean startLocalTransaction，Boolean releaseConnectionOnSuccess）
在System.Data.Entity.Core.Objects.ObjectQuery`1.c__DisplayClass7.b__5（）中
在System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult]（Func`1操作）中
位于System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults（可空`1
[Obsolete("Only needed for serialization and materialization", true)]
public PlayerData() {}

public PlayerData(Player player)
{
}