BIRT Report with JSON Column data to table - json

Question

I have a PostgreSQL table that stores some information in a JSON column, I'd like to take the data from this JSON column and populate a secondary table in the BIRT report.
I've got the data into a JSON object just fine, I can use it, but table #2 won't populate any data even though there is data in the JSON object.
DataSource1 it attached to DataSet1 which is PostgreSQL. DataSource2 is a scripted DS, and it has Dataset2 attached to it with columns defined.
In dataset1 I have the OnFetch function making my JSON array:
vars["invoiceData"] = JSON.parse(row["i_invoice"]);
Then I have in dataset2 (json dataset) I have this for the fetch event setup:
// Get the length of the object
len = vars["invoiceData"].labor.length;
count = 0;// Counter used to step through each item in the JSON object.
// Loop through the JSON object adding it to the scripted data source
if(count < len && len != 0) {
row["hrs"] = vars["invoiceData"].labor[count].hrs;
row["desc"] = vars["invoiceData"].labor[count].desc;
row["rate"] = vars["invoiceData"].labor[count].rate;
row["amount"] = vars["invoiceData"].labor[count].amount;
count++;
return true;
}
return false;
If I echo out the length of my array it has one row in it, but that table never comes back with anything, always empty on my report.

Answer 1

You are mixing initialization code with loop code.
Just think about this fragment:
count = 0;
if (...) {
count++;
return true;
}
return false;
You need to split and modify this code. Basically, for a scripted data set you need three things:
A counter variable (or something similar). This is best declared as a report variable.
Initialization of the counter variable in the data set's open event.
Using the counter variable in the data set's fetch event, eg modifying it and comparing it to the data length.
Your code will return the first data row in an endless loop, because what BIRT does is:
open()
while fetch():
emit the current row
Thus, your code is definitely wrong.
OTOH the behavior that you describe doesn't match what I would expect: A never-ending report. So there are probably other errors in your report. What does the "problems" view in the BIRT designer show?