Question

我在将dynamic参数传递给异步方法时遇到问题。编译时错误为Argument 1: cannot convert from 'System.Collections.Generic.IEnumerable<dynamic>' to 'System.Collections.Generic.IEnumerable<System.Threading.Tasks.Task>'。

实际上，我正在尝试记录每个数据库表列条目的条目。因此，我正在使用一种通用方法，该方法采用动态oldervalue和newvalue并将其插入到AuditDB中。

代码

    public async Task Translog(int Id, string Action, DateTime RecordTimeStamp, dynamic oldervalue, dynamic newvalue, VIBRANT db, VibrantAuditEntities context)
    {
        try
        {
            #region FrameLog
            Type typeOfMyObject;
            if (oldervalue != null)
                typeOfMyObject = oldervalue.GetType();
            else
                typeOfMyObject = newvalue.GetType();

            PropertyInfo[] properties = typeOfMyObject.GetProperties();

            var tasks = properties.ToList().Select(i => SetPropValuess(typeOfMyObject, i, Id, Action, RecordTimeStamp, oldervalue, newvalue, db, context));
            await Task.WhenAll(tasks); // Compile error at this line

            #endregion
        }
        catch
        {
            throw;
        }
    }

    public async Task SetPropValuess(Type typeOfMyObject, PropertyInfo item, int Id, string Action, DateTime RecordTimeStamp, dynamic oldervalue, dynamic newvalue, VIBRANT db, VibrantAuditEntities context)
    {
        await Task.Run(() =>
        {
            string PropertyTypeNamespace = typeOfMyObject.GetProperty(item.Name).PropertyType.Namespace;
            if (PropertyTypeNamespace != "System.Collections.Generic" && PropertyTypeNamespace != "ClassLibrary")
            {
                if (oldervalue != null && newvalue != null)
                {
                    //Edit
                    bool chk = Comparer.Equals(oldervalue.GetType().GetProperty(item.Name).GetValue(oldervalue, null), newvalue.GetType().GetProperty(item.Name).GetValue(newvalue, null));
                    if (chk == false)
                    {
                        //  make and add log record
                        AuditLog al = new AuditLog();
                        al.TableName = (typeOfMyObject.BaseType.Name == "Object" ? typeOfMyObject.Name : typeOfMyObject.BaseType.Name);
                        al.EventDateUTC = RecordTimeStamp;
                        al.OriginalValue = Convert.ToString(oldervalue.GetType().GetProperty(item.Name).GetValue(oldervalue, null));
                        al.NewValue = Convert.ToString(newvalue.GetType().GetProperty(item.Name).GetValue(newvalue, null));
                        al.ColumnName = item.Name;
                        context.AuditLogs.Add(al);
                    }
                }
                else if (oldervalue != null && newvalue == null)
                {
                    //Delete
                    AuditLog al = new AuditLog();
                    al.TableName = (typeOfMyObject.BaseType.Name == "Object" ? typeOfMyObject.Name : typeOfMyObject.BaseType.Name);
                    al.EventDateUTC = RecordTimeStamp;
                    al.OriginalValue = Convert.ToString(typeOfMyObject.GetProperty(item.Name).GetValue(oldervalue, null));
                    al.NewValue = null;
                    al.ColumnName = item.Name;
                    al.EventType = Action;
                    context.AuditLogs.Add(al);
                }
                else if (oldervalue == null && newvalue != null)
                {
                    //Create
                    AuditLog al = new AuditLog();
                    al.TableName = (typeOfMyObject.BaseType.Name == "Object" ? typeOfMyObject.Name : typeOfMyObject.BaseType.Name);
                    al.EventDateUTC = RecordTimeStamp;
                    al.OriginalValue = null;
                    al.NewValue = Convert.ToString(typeOfMyObject.GetProperty(item.Name).GetValue(newvalue, null));
                    al.ColumnName = item.Name;
                    context.AuditLogs.Add(al);
                }
            }
        });
    }

Answer 1

这很奇怪，由于某种原因，存在“动力”类型参数的事实会影响“任务”的类型。如果删除了动态参数，那么它将起作用。作为一种解决方法，您可以添加强制类型转换，但了解为什么会发生这种情况将很有趣：

            var tasks = properties
                .ToList()
                .Select(i => SetPropValuess(typeOfMyObject, i, Id, Action, RecordTimeStamp, oldervalue, newvalue, db, context))
                .Cast<Task>();

异步等待不适用于动态参数

1 个答案: