Issue when looping over a complex list subtracting datetimes and expecting a duration, but receiving a null

Question

I am trying to loop through a complex list with Start and End DateTime properties and return a list of durations. Using a FEEL expression for t in Times return t.End - t.Start it returns null.

To verify that I was pulling back the correct values I just returned t.End and the expected DateTime returned.

Next, I tried the same thing but removed the list from the complex object Time.End - Time.Start a duration object returns as expected.

{
  "Times": [
    {
      "Start": "2024-06-05T11:35:02.534Z",
      "End": "2024-06-05T11:40:02.534Z"
    },
    {
      "Start": "2024-06-05T11:35:02.534Z",
      "End": "2024-06-05T11:45:02.534Z"
    }
  ],
  "Time": {
    "Start": "2024-06-05T11:35:02.534Z",
    "End": "2024-06-05T11:40:02.534Z"
  }
}

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  return t.End - t.Start</dmn:text>
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So, in summary, when I have a structured object with a Start Datetime and End Datetime I can return a duration with "Time.End - Time.Start", but I can't do the same for a complex list "for t in Times return t.End - t.Start. Given the above Times object how can I loop through the list and return the a list of durations?

Answer 1

Hi it should be possible, I am sending picture with successful evaluation. Please notice I have used date and time function to be sure string is converted to date and time data type.