Sorting JObject inside array by a field value

Question

I have a JSON string like below:

{
  "MetaData": {
    "ResourcesUsed": 1
  },
  "Result": [
    {
      "locations": [
        {
          "country": "Papua New Guinea",
          "city": "Jacquinot Bay",
          "locTypeAttributes": {
            "localDate": "2018-10-08T04:21:00-07:00",
            "utcDate": "2018-10-08T04:21:00-07:00",
          },
          "point": {
            "coordinates": [
              151.52,
              -5.6
            ],
            "type": "Point"
          }
        },{
          "country": "Papua New Guinea2",
          "city": "Jacquinot Bay2",
          "locTypeAttributes": {
            "localDate": "2018-10-08T04:21:00-07:00",
            "utcDate": "2018-10-02T04:21:00-07:00",
          },
          "point": {
            "coordinates": [
              151.52,
              -5.6
            ],
            "type": "Point"
          }
        }
      ]
    }
  ]
}

I converted it to a JSON object using Newtonsoft. What I want to do is to sort the locations array(s) inside the Result array by the utcDate field nested in each locations item. I found the following thread: C# Sort JSON string keys. However, I could not still implement it since I have arrays inside my object, while that question deals purely with sorting objects inside objects alphabetically by property name.

Here is a piece of code that I wrote so far:

public string GenerateJson()
{
     var model = (JObject)JsonConvert.DeserializeObject(data);
     Sort(model);
}
private void Sort(JObject jObj)
{
    var props = jObj["Result"][0]["locations"].ToList();
    foreach (var prop in props)
    {
        prop.Remove();
    }

    foreach (var prop in props.OrderBy(p => p.Name))
    {
        jObj.Add(prop);
        if (prop.Value is JObject)
            Sort((JObject)prop.Value);
        if (prop.Value is JArray)
        {
            Int32 iCount = prop.Value.Count();
            for (Int32 iIterator = 0; iIterator < iCount; iIterator++)
                if (prop.Value[iIterator] is JObject)
                    Sort((JObject)prop.Value[iIterator]);
        }
    }
}

Answer 1

You can sort each individual "Result[*].locations" array using LINQ as follows:

// Load the JSON without parsing or converting any dates.
var model = JsonConvert.DeserializeObject<JObject>(data, new JsonSerializerSettings{ DateParseHandling = DateParseHandling.None });

// Construct a serializer that converts all DateTime values to UTC
var serializer = JsonSerializer.CreateDefault(new JsonSerializerSettings{ DateTimeZoneHandling = DateTimeZoneHandling.Utc });

foreach (var locations in model.SelectTokens("Result[*].locations").OfType<JArray>())
{
    // Then sort the locations by utcDate converting the value to UTC at this time.
    var query = from location in locations
                let utcDate = location.SelectToken("locTypeAttributes.utcDate").ToObject<DateTime>(serializer)
                orderby utcDate
                select location;
    locations.ReplaceAll(query.ToList());
}

Notes:

• The JSON is initially loaded using DateParseHandling.None to prevent the "localDate" and "utcDate" strings from being prematurely interpreted as DateTime objects with a uniform DateTime.Kind.

  (For a discussion of how Json.NET interprets strings that look like dates, see Serializing Dates in JSON.)

• We then iterate through all "locations" arrays using SelectTokens("Result[*].locations") where [*] is the JSONPath wildcard character, selecting all entries in the "Results" array.

• We then order each "locations" array by deserializing the nested locTypeAttributes.utcDate to a UTC date, then ordering using LINQ.

• Finally the array is updated using JArray.ReplaceAll().

• If any locTypeAttributes.utcDate property is missing, an exception will be thrown. You could instead deserialize to DateTime? if that is a possibility.

Working sample .Net fiddle here.