JSON in JMeter

http://jmeter.512774.n5.nabble.com/Require-help-in-Regular-Expression-td5713320.html
Roughly user gets a JSON response and wants to use some of that data for the next JSON request. Using a regular expression to extract out multiple related data is sometimes painful. So the alternative I suggest is to use JMeter to parse the JSON object and then use it (The other would be to have JMeter to natively support JSON , but unless JMeter also has a mapping tool , this only saves two lines of code , so I don't think its that useful).

So first we download Douglas Crockford's reference implementation from JSON in java , compile it and generate a jar and copy it into JMeter's lib directory (please ensure you compile it with a java version that is compatible with whatever you will use to run JMeter) - and don't use this library for evil.

Next launch JMeter.

To spoof this example , we create a BeanShell sampler that will return the JSON string we are interested in. To this sampler we add a BeanShell post processor that will parse the response and form the object that we need for the next request. The code is given below

import org.json.JSONArray;
import org.json.JSONObject;

String jsonString = prev.getResponseDataAsString();
JSONArray equipmentParts = new JSONArray(jsonString);
JSONArray parts = new JSONArray();

for(int i=0;i<equipmentParts.length();i++ ){
    JSONObject equipmentPart = equipmentParts.getJSONObject(i).getJSONObject("equipmentPart");
    JSONObject allAttributes = equipmentPart.getJSONObject("allAttributes");
    JSONObject part = new JSONObject();
    part.put("partId",allAttributes.getLong("equipmentPartId"));
    part.put("partNumber",allAttributes.getString("compositePartName"));
    // add more here
    parts.put(part);
}

vars.put("jsonResponse", parts.toString());

Note we first get the response as a string. Then we just use the JSON libraries to parse this string into a JSON array (equipmentParts). After which we iterate over every object, extract out the attributes we are interested in (you could even have an array of attributes and have a simpler loop) and then we start forming the object we want to post (i.e. the parts JSON array and the part JSON object)

Next we simply convert the JSON parts array into a String to be used by the next sampler by setting it into the jmeter variable jsonResponse.

The next sampler simply uses a POST and only specifies the variable ${jsonResponse} in the value field(So that it will be used as is in the body).
We run the script. The Debug Sampler is used to verify that the value we setup is correct and that it does get posted in the next request

Sample code is available here https://skydrive.live.com/#cid=1BD02FE33F80B8AC&id=1BD02FE33F80B8AC!876