Need to form custom request in jmeter

I am in need to create a custom request in jmeter which looks like the below format:

{
"items": [
        {
            "id": "1",
            "productId": 1234
         }
        {
            "id": "2",
            "productId": 1218
        }
....
}

Here I have to generate some random number in between 10-15 and create the id blocks(based on the random number). Could someone please help how can I form the request accordingly and achieve this in jmeter.

Thanks in advance.

1. Add JSR223 PreProcessor as a child of the request which need to send this generated value

2. Put the following code into "Script" area

   import groovy.json.JsonBuilder
   import org.apache.commons.lang3.RandomUtils
   
   
   def items = []
   def itemsNo = RandomUtils.nextInt(10, 16)
   
   1.upto(itemsNo) { id ->
       def productId = RandomUtils.nextInt(1111, 10000)
       def item = [:]
       item.put('id', id as String)
       item.put('productId', productId)
       items.add(item)
   }
   
   def payload = new JsonBuilder([items: items]).toPrettyString()
   vars.put('payload',payload)
   

3. Use ${payload} JMeter Variable where you need to refer the generated JSON

Demo:

More information:

• Apache Groovy - Parsing and producing JSON
• Apache Groovy - Why and How You Should Use It