Replace null value with default text

Question

I know this question has been asked many times, but I have the following piece of code that I am trying to use to default null values. Can someone please help me. I tried this code but instead of giving me "NO DATA" for the null values, it doesnt display anything. Not sure where I am going wrong.

More Detail: This code does not replace null values with "NO DATA" string. What is wrong here? What do I need to change in order for it to display "NO DATA"?

protected override void Execute(NativeActivityContext context)
    {
        DataSet dataset = GetDataSet.Get(context);
        foreach (DataTable dt in dataset.Tables)
        {
            foreach (DataRow row in dataset.Tables[0].Rows)
            {
                if (row["USER_COMMENT"] is System.DBNull)
                {
                    ConvertNullToEmptyString(dt);
                    Console.WriteLine("In if");
                }
                else
                {
                    Console.WriteLine("out if");
                }
            }
        }
         TransformResult.Set(context, dataset);
    }


    private static string ConvertNullToEmptyString(DataTable element)
    {
        if (element.Rows[0]["USER_COMMENT"] == DBNull.Value || element.Rows[0]["USER_COMMENT"] == null)
        {
            return "NO DATA";
        }
        else
        {
            return element.Rows[0]["USER_COMMENT"].ToString();
        }
    }

Answer 1

No need of extra function there. You just have to insert the "No DATA" in the loop like below

 foreach (DataRow row in dataset.Tables[0].Rows)
        {
            if (row["USER_COMMENT"] is System.DBNull)
            {
                row["USER_COMMENT"] = "NO DATA";
                Console.WriteLine("In if");
            }
            else
            {
                Console.WriteLine("out if");
            }
        }

Answer 2

Use empty string instead of null

if(row["USER_COMMENT"] == string.Empty)

Answer 3

Here is what I would do

String stringtocompare;

     if(String.isnullorwhitespace(stringtocompare)){
         stringtocompare = "No VALUE";
      }

Answer 4

Did you try

private static string ConvertNullToEmptyString(DataTable element)
    {
        if (string.IsNullOrEmpty(element.Rows[0]["USER_COMMENT"]))
        {
            return "NO DATA";
        }
        else
        {
            return element.Rows[0]["USER_COMMENT"].ToString();
        }
    }

Answer 5

A couple things that might help:

You probably want to change this:

foreach (DataTable dt in dataset.Tables)
    {
        foreach (DataRow row in dataset.Tables[0].Rows)
        {
        ...

to this:

foreach (DataTable dt in dataset.Tables)
    {
        foreach (DataRow row in dt.Rows)
        {
        ...

Or else you will only be querying 1 table in your loop.

Also, I'd use String.IsNullOrEmpty() to interrogate the data.

Answer 6

If you don't need a second function to do it, try something like this:

protected override void Execute(NativeActivityContext context) {
  DataSet dataset = GetDataSet.Get(context);
  foreach(DataTable dt in dataset.Tables) {
    foreach(DataRow row in dt.Rows) {
      row["USER_COMMENT"] = String.IsNullOrEmpty(row["USER_COMMENT"].ToString()) ? "NO DATA" : row["USER_COMMENT"];
    }
  }
  TransformResult.Set(context, dataset);
}

But, with a second function to convert, it would look something like this:

protected override void Execute(NativeActivityContext context) {
  DataSet dataset = GetDataSet.Get(context);
  foreach(DataTable dt in dataset.Tables) {
    foreach(DataRow row in dt.Rows) {
      row["USER_COMMENT"] = ConvertNullToEmptyString(row["USER_COMMENT"]);
    }
  }
  TransformResult.Set(context, dataset);
}

private static object ConvertNullToEmptyString(object element) {
  if(String.IsNullOrEmpty(element.ToString())) {
    return "NO DATA";
  } else {
    return element;
  }
}