Convert a list of objects into a list of new generic objects who contain a list property

Question

I have a list of objects in which one of the properties of the object is a date string, if in JSON it would look like this below:

// this is a List<Measurements>

measurements: [
    {
      "Timestamp": "6/7/2016 10:25:27 AM",
      "FactoryTimestamp": "6/7/2016 10:25:27 AM",
      "ValueInMgPerDl": 265,
      "TrendArrow": 4
    },
    {
      "Timestamp": "6/7/2016 10:24:27 AM",
      "FactoryTimestamp": "6/7/2016 10:24:27 AM",
      "ValueInMgPerDl": 301,
      "TrendArrow": 5
    },
    {
      "Timestamp": "6/6/2016 11:24:27 PM",
      "FactoryTimestamp": "6/6/2016 11:24:27 PM",
      "ValueInMgPerDl": 102,
      "TrendArrow": 2
    },
    {
      "Timestamp": "6/6/2016 11:23:27 PM",
      "FactoryTimestamp": "6/6/2016 11:23:27 PM",
      "ValueInMgPerDl": 99,
      "TrendArrow": 2
    }
]

I'm trying to create a new list of objects out of this in which they are grouped by the Timestamp param with the hopes that I don't need to create a new type but can instead use a generic. This way the new list would look something like this:

measurementGroups [
      {
        "date": "6/7/2016 10:25:27 AM",
        "measurementData" : [
          {
            "Timestamp": "6/7/2016 10:25:27 AM",
            "FactoryTimestamp": "6/7/2016 10:25:27 AM",
            "ValueInMgPerDl": 265,
            "TrendArrow": 4          
          },
          {
            "Timestamp": "6/7/2016 10:24:27 AM",
            "FactoryTimestamp": "6/7/2016 10:24:27 AM",
            "ValueInMgPerDl": 301,
            "TrendArrow": 5
          }
        ]
      },
      {
        "date": "6/6/2016 11:24:27 PM",
        "measurementData" : [
          {
            "Timestamp": "6/6/2016 11:24:27 PM",
            "FactoryTimestamp": "6/6/2016 11:24:27 PM",
            "ValueInMgPerDl": 102,
            "TrendArrow": 2         
          },
          {
            "Timestamp": "6/6/2016 11:23:27 PM",
            "FactoryTimestamp": "6/6/2016 11:23:27 PM",
            "ValueInMgPerDl": 99,
            "TrendArrow": 2
          }
      }
    ]

I tried accomplishing this using Linq like I show below, but that that's only returning me a list of lists grouped by date. Am I able to achieve what I'm after with Linq or is there another approach I need to take?

// Current attempt using linq
 var measurementGroupList = measurements
         .GroupBy(d => Convert.ToDateTime(d.Timestamp).Date)
         .Select(grp => grp.ToList())
         .ToList();

The groupBy is returning a 2 dimensional list of keys with a list of values for each key. To get the individual values you need to use two Select methods .Select(grp => grp).Select(item => ........ — jdweng
– jdweng, Commented Jun 8, 2016 at 16:47
In a typical situation I would be fine with the way the GroupBy is returning the data. In this case I need to have the data structured similar to the middle example. — Stavros_S
– Stavros_S, Commented Jun 8, 2016 at 16:49

Vladimir Gabrielyan · Accepted Answer · 2016-06-08 17:10:21Z

1

I assume that you have a class Measurements

public class Measurements
{
    public DateTime Timestamp { get; set; }
    public DateTime FactoryTimestamp { get; set; }
    public int ValueInMgPerDl { get; set; }
    public int TrendArrow { get; set; }
}

and var MeasurementsList = new List<Measurements>(){.....} and on top of that try following query

    var measurementGroupList= MeasurementsList.GroupBy(s => s.Timestamp).Select(grp => new { date = grp.Key, measurementData = grp.Select(s => s) }).ToList();

answered Jun 8, 2016 at 17:10

Vladimir Gabrielyan

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