Question

我希望得到10条最新的（orderbydescenting datetime）记录，这些记录应该是唯一的，并且不应为null（ACnrAAAAAAAAAAA =）值。

示例数据

AGMDAQo1/wSsCPU=
AGjtAAAAAAAAAAA=(this should be discarded as treating null values)
AGMDAQo1/wSsCPU=
ACnrAAAAAAAAAAA=(this should be discarded as treating null values)
AWa2AQo2CQSsCNE=

json数据

[{"timestamp":"2017-03-20T05:27:01.688Z","dataFrame":"ACnrAAAAAAAAAAA=","fcnt":165,"port":3,"rssi":-85,"snr":7,"sf_used":12,"id":1489987621688,"decrypted":true},{"timestamp":"2017-03-20T05:27:41.675Z","dataFrame":"ACntAAAAAAAAAAA=","fcnt":169,"port":3,"rssi":-85,"snr":9,"sf_used":12,"id":1489987661675,"decrypted":true}]

期望的操作

AGMDAQo1/wSsCPU=
AWa2AQo2CQSsCNE=

码

using (var stream = resp.GetResponseStream())
                    {
                        var reader = new StreamReader(stream, encoding);
                        var responseString = reader.ReadToEnd();
                        var Pirs = Newtonsoft.Json.JsonConvert.DeserializeObject<List<AssetDetail>>(responseString).OrderByDescending(AssetDetail=>AssetDetail.timestamp).Take(10);
                        foreach (var item in Pirs)
                        {
                        }

Answer 1

为什么不提供Where条款？你还没有提到你在你的例子中打印到控制台的确切内容，但应该是这样的：

var items = Newtonsoft.Json.JsonConvert.DeserializeObject<List<AssetDetail>>(responseString);     
var eligibleItems = items.Where(a => !a.dataFrame.EndsWith("AAAAAAAAAAA="))
                         .GroupBy(a => a.dataFrame)   
                         .Select(g=> g.First())   
                         .OrderByDescending(a => a.timestamp)
                         .Take(10);

如何使用linq查询获取没有空值的最新的10条记录

1 个答案: