The Predictor class

There are a couple of changes in this class to handle the employment prediction scenario:

1. First, validate that the input file exists before making a prediction on it:

if (!File.Exists(inputDataFile))
{
    Console.WriteLine($"Failed to find input data at {inputDataFile}");
    
    return;
}

2. The other change is in the prediction call itself. As you probably guessed, the TSrc and TDst arguments need to be adjusted to utilize both of the new classes we created, EmploymentHistory and EmploymentHistoryPrediction:

var predictionEngine = MlContext.Model.CreatePredictionEngine<EmploymentHistory, EmploymentHistoryPrediction>(mlModel);

3. Given that we are no longer simply passing in the string and building an object on the fly, we need to first read in the file as text. We then deserialize the JSON into our EmploymentHistory object:

var json = File.ReadAllText(inputDataFile);

var prediction = predictionEngine.Predict(JsonConvert.DeserializeObject<EmploymentHistory>(json));

4. Lastly, we need to adjust the output of our prediction to match our new EmploymentHistoryPrediction properties:

Console.WriteLine(
 $"Based on input json:{System.Environment.NewLine}" +
 $"{json}{System.Environment.NewLine}" + 
 $"The employee is predicted to work {prediction.DurationInMonths:#.##} months");