How to get multiple values from a CSV file inside of one test iteration - jmeter

Question

I need to dynamically generate an XML or JSON in an iteration where the XML or JSON has a variable number of elements -- e.g., it could be books. The values of the books come from the CSV file.
I created a CSV Data Config that point to the CSV file with a variable called csvBook.
Next, in a BeanShell Sampler, I call
StringBuffer sb = new StringBuffer("<Order><Books>");
Random rv = new Random();
int size = rv.nextInt(100);
for (int i = 0; i < size; i++) {
sb.append("<Book Name=" + vars.get("csvBook") + "/>");
}
sb.append("</Books></Order>");
The problem is I don't know how to get new values from the CSV file as I run through the loop inside one iteration. The vars.get("csvBook") returns the same value in the same iteration.
Is there a command to tell JMeter to get the next CSV value (next row) (again, inside one iteration)?
Thanks in advance.

Answer 1

Consider switching to JSR223 Sampler and Groovy language as:
Groovy has built-in support for JSON
Groovy has built-in support for XML
Groovy performance is much better than Beanshell
The relevant Groovy code would be something like:
import groovy.xml.StreamingMarkupBuilder
def csvFile = new File('/path/to/csv/file')
def payload = {
order {
books {
csvFile.readLines().each {line ->
book (name:line)
}
}
}
}
def xmlFile = new File('/path/to/xml/file')
def writer = xmlFile.newWriter()
def builder = new StreamingMarkupBuilder()
def writable = builder.bind payload
writable.writeTo(writer)