iReport parameter not being informed by field - jasper-reports

Question

I am using iReport - my first time using it - and I am trying to make a report that will involve passing a parameter to a subreport. I am not able to get that to work, so I did the following test:
I have a large query that grabs various Fields from my DB - when I preview the report these fields are being pulled and display (over and over, etc., a lot of stuff is being pulled).
I created a new parameter on the main report called "myparam". I made it's default value one of the fields that is being successfully pulled from my DB.
I created a textfield to display this param - the intent being it will echo the field that displays already in my report. If I can get it to do that, I figure I can get it to correctly "plug in" to my subreport.
The issue is - when I preview, I am asked to give the parameter a value - I choose default, which defaults it to the Field I set, which means it should now echo that field (aka I WANT it to echo that field). But it does not echo that field. Instead it just shows null over and over again. Here is a screenshot of what I am talking about
Here is the setup for my report:
Here is proof I've set the default value in my xml:
<parameter name="myparam" class="java.lang.String">
<defaultValueExpression><![CDATA[$F{TCORDERID}]]> </defaultValueExpression>
</parameter>
Here is a snippet of the report which is being generated incorrectly (aka myparam is not getting populated right).
THEY ARE BOTH STRINGS

Answer 1

From my understanding of parameters, they are passed to the report/subreport when it gets created. You have set the default value of the parameter to one of your fields, which has not been populated yet when the report gets generated.
I would suggest adding a simple subreport (which is the reason you want to use parameters anyway), remove the parameter on the main report, and add it to the subreport (with a text field to display it).
Now, add the Parameter to the subreport object in your main report. (This is under the Subreport properties section in iReport.
Name: The name of the Parameter in the subreport.
Expression: The field from your main report that will be passed to the subreport.
So your main report will have the following under the subreport detail:
<subreportParameter name="myparam">
<subreportParameterExpression><![CDATA[$F{TCORDERID}]]></subreportParameterExpression>
</subreportParameter>
And then the Parameter in the subreport:
<parameter name="myparam" class="java.lang.String">
<defaultValueExpression><![CDATA["No result"]]></defaultValueExpression>
</parameter>