Example of implementing a really, really basic DLLExport of Newtonsoft.Json reader and writer in Clarion. But it works pretty darn well! http://james.newtonking.com/projects/json/help/html/ReadingWritingJSON.htm

GetJsonData.clw

GetJsonData PROCEDURE(LONG pDate)
Json JsonClassType
  CODE

  Json.Init()
  Json.InitWriter()
  Json.WriteStartObject()

  Json.WritePropertyName('key')
  Json.WriteValue('ASDR-WERT-DFGG-RRTY')

  Json.WritePropertyName('bufferTime')
  Json.WriteValue('300')

  Json.WritePropertyName('vehicles')
  Json.WriteStartArray()

  Clear(JOU:Record)
  JOU:Date_Date_DATE = pDate
  Set(JOU:FK_Journeys_Dateline, JOU:FK_Journeys_Dateline)
  LOOP UNTIL Access:Journeys.Next() <> Level:Benign OR JOU:Date_Date_DATE <> pDate
    VEH:Rego = JOU:Vehicle
    IF Access:Vehicle.Fetch(VEH:K_Rego) <> Level:Benign
      CYCLE
    END
    Json.WriteStartObject()

    Json.WritePropertyName('rego')
    Json.WriteValue(VEH:Rego)

    Json.WritePropertyName('location')
    Json.WriteValue('some location')

    Json.WritePropertyName('seats')
    Json.WriteValue(VEH:Seats )

    Json.WritePropertyName, 'costPerKm')
    Json.WriteValue(VEH:CostPerKm)

    Json.WriteEnd()
  END
  Json.WriteEndArray()

  Json.WriteEndObject()
  RETURN Json.ToJson()


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The return will look something like this:

  {
  "key": "ASDR-WERT-DFGG-RRTY!",
  "bufferTime": "300",
  "vehicles": [
    {
      "rego": "CT2345",
      "location": "some location",
      "seats": "4",
      "costPerKm": "0.42"
    },
    {
      "rego": "ABC-123",
      "location": "some location",
      "seats": "0",
      "costPerKm": "0"
    },
    {
      "rego": "XXYY",
      "location": "some location",
      "seats": "0",
      "costPerKm": "0"
    }
  ]
}