我正在尝试实现一个方法来检索表中的所有行,按ID降序排序.
这是代码:
public IEnumerable<T> GetItemsDescending<T>() where T : IBusinessEntity,new() { lock (locker) { return Table<T>().Select(i => i).OrderByDescending(xx => xx.ID).ToList(); } }
这看起来应该可行,但我收到一个我不明白的错误:
"Order By does not support: xx => Convert(xx).ID"
private TableQuery<T> AddOrderBy<U>(Expression<Func<T,U>> orderExpr,bool asc) { if (orderExpr.NodeType == ExpressionType.Lambda) { var lambda = (LambdaExpression)orderExpr; MemberExpression mem = null; var unary = lambda.Body as UnaryExpression; if (unary != null && unary.NodeType == ExpressionType.Convert) { mem = unary.Operand as MemberExpression; } else { mem = lambda.Body as MemberExpression; } if (mem != null && (mem.Expression.NodeType == ExpressionType.Parameter)) { var q = Clone<T>(); if (q._orderBys == null) { q._orderBys = new List<Ordering>(); } q._orderBys.Add(new Ordering { ColumnName = Table.FindColumnWithPropertyName(mem.Member.Name).Name,Ascending = asc }); return q; } else { throw new NotSupportedException("Order By does not support: " + orderExpr); } } else { throw new NotSupportedException("Must be a predicate"); } }
按要求:PanelLog类:
public class PanelLog : IBusinessEntity { public PanelLog() { } [PrimaryKey,AutoIncrement] public int ID { get; set; } public uint Sequence { get; set; } public DateTime Time { get; set; } public string Message { get; set; } public bool Alarm { get; set; } }
解决方法
没有答案?
好吧,这就是我正在做的工作:
public static IEnumerable<PanelLog> GetPanelLogsDescendingsql(params object[] args) { return me.db.Query<PanelLog>("select * from PanelLog ORDER BY ID DESC"); }