在Entity Framework DbContext中使用Newtonsoft.Json，不会为成员异常解析Type

在我的 DbContext 类中，我刚刚添加了对 Newtonsoft.Json 的一些引用，因为我正在使用它来存储用于审计的实体的序列化版本 .

现在，当我运行 update-database 命令时，我在控制台中得到以下内容 .

指定'-Verbose'标志以查看应用于目标数据库的SQL语句 . 没有待定的显式迁移 . 运行种子方法 . System.Runtime.Serialization.SerializationException：成员'Newtonsoft.Json.JsonSerializationException，Newtonsoft.Json，Version = 7.0.0.0，Culture = neutral，PublicKeyToken = 30ad4fe6b2a6aeed'的类型未解析 . 在System.Data.Entity.Migrations.Design.ToolingFacade.Run（BaseRunner runner）的System.AppDomain.DoCallBack（CrossAppDomainDelegate callBackDelegate）处于System.Data.Entity.Migrations.Design.ToolingFacade.Update（String targetMigration，Boolean force）at at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute（Action命令）System.Data.Entity.Migrations.UpdateDatabaseCommand . <> c__DisplayClass2 . < . ctor> b__0（）处理成员'Newtonsoft.Json.JsonSerializationException的类型未解析， Newtonsoft.Json，Version = 7.0.0.0，Culture = neutral，PublicKeyToken = 30ad4fe6b2a6aeed' .

所有引用都很好， Newtonsoft.Json dll在输出目录中 .

有谁知道让这个工作的方法？

谢谢

史蒂夫

编辑：

public EFDbContext(string nameOrConnectionString = "DbConnectionString") : base(nameOrConnectionString)
{

     IObjectContextAdapter adapter = this;
     adapter.ObjectContext.SavingChanges += ObjectContextOnSavingChanges;

}

/// <summary>
/// Audits the records.
/// </summary>
/// <param name="objectContext">The object context.</param>
public void AuditRecords(ObjectContext objectContext)
{
    IEnumerable<ObjectStateEntry> changes = objectContext.ObjectStateManager.GetObjectStateEntries(EntityState.Added | EntityState.Deleted | EntityState.Modified);
    foreach (ObjectStateEntry stateEntryEntity in changes)
    {
        if (!stateEntryEntity.IsRelationship && stateEntryEntity.Entity != null && !(stateEntryEntity.Entity is AuditEntry))
        {
            AuditEntry audit = CreateAuditRecord(stateEntryEntity, objectContext);
            this.AuditEntries.Add(audit);
        }
    }
}

/// <summary>
/// Creates the audit record.
/// </summary>
/// <param name="objectStateEntry">The object state entry.</param>
/// <param name="objectContext">The object context.</param>
/// <returns>AuditEntry.</returns>
public AuditEntry CreateAuditRecord(ObjectStateEntry objectStateEntry, ObjectContext objectContext)
{
    AuditEntry audit = new AuditEntry();

    audit.TableName = objectStateEntry.EntitySet.Name;
    audit.ApplicationUserId = UserId;

    if (objectStateEntry.State == EntityState.Added)
    {//entry is Added 
        audit.NewValue = GetEntryValueInString(objectStateEntry, false);
        audit.Action = AuditAction.Add;
    }
    else if (objectStateEntry.State == EntityState.Deleted)
    {//entry in deleted
        audit.OldValue = GetEntryValueInString(objectStateEntry, true);
        audit.Action = AuditAction.Delete;
    }
    else
    {//entry is modified
        audit.OldValue = GetEntryValueInString(objectStateEntry, true);
        audit.NewValue = GetEntryValueInString(objectStateEntry, false);
        audit.Action = AuditAction.Update;

        IEnumerable<string> modifiedProperties = objectStateEntry.GetModifiedProperties();
        //assing collection of mismatched Columns name as serialized string 
        audit.ChangedColumns = JsonConvert.SerializeObject(modifiedProperties.ToArray());
    }

    return audit;

}

/// <summary>
/// Clones the entity.
/// </summary>
/// <param name="obj">The object.</param>
/// <returns>EntityObject.</returns>
public object CloneEntity(BaseEntity obj)
{
    return JsonConvert.DeserializeObject(JsonConvert.SerializeObject(obj), obj.GetType());
}

/// <summary>
/// Gets the entry value in string.
/// </summary>
/// <param name="entry">The entry.</param>
/// <param name="isOrginal">if set to <c>true</c> [is orginal].</param>
/// <returns>System.String.</returns>
private string GetEntryValueInString(ObjectStateEntry entry, bool isOrginal)
{

    if (entry.Entity is BaseEntity)
    {
        object target = CloneEntity((BaseEntity)entry.Entity);
        foreach (string propName in entry.GetModifiedProperties())
        {
            object setterValue = null;
            if (isOrginal)
            {
                setterValue = entry.OriginalValues[propName];
            }
            else
            {
                setterValue = entry.CurrentValues[propName];
            }

            PropertyInfo propInfo = target.GetType().GetProperty(propName);

            if (setterValue == DBNull.Value)
            {
                setterValue = null;
            }
            propInfo.SetValue(target, setterValue, null);
        }

        return JsonConvert.SerializeObject(target);
    }
    return null;
}