JMeter: How to count JSON objects in an Array using jsonpath

Question

In JMeter I want to check the number of objects in a JSON array, which I receive from the server.

For example, on a certain request I expect an array with 5 objects.

[{...},{...},{...},{...},{...}]

After reading this: count members with jsonpath?, I tried using the following JSON Path Assertion:

JSON Path: $
Expected value: hasSize(5)
Validate against expected value = checked

However, this doesn't seem to work properly. When I actually do receive 5 objects in the array, the response assertion says it doesn't match.

What am I doing wrong? Or how else can I do this?

Check this answer: stackoverflow.com/a/40926919/1306012 you may look for that. Use the "*_matchNr" of your variable. — Bruno Bieri
– Bruno Bieri, Commented Jan 19, 2017 at 14:44

gazzo · Accepted Answer · 2019-04-30 14:20:12Z

13

Although JSONPath Extractor doesn't provide hasSize function it still can be done.

Given the example JSON from the answer by PMD UBIK-INGENIERIE, you can get matches number on book array in at least 2 ways:

1. Easiest (but fragile) way - using Regular Expression Extractor.

As you can see, there are 4 entries for category like:

{ "category": "reference",
{ \"category\": \"fiction\"
...

If you add a Regular Expression Extractor configured as follows:

JSON Regex

It'll capture all the category entries and return matches number as below:

JSON Regex Matches

So you will be able to use this ${matches_matchNr} variable wherever required.

This approach is straightforward and easy to implement but it's very vulnerable to any changes in the response format. If you expect that JSON data may change in the foreseeable future continue with the next option.

2. Harder (but more stable) way - calling JsonPath methods from Beanshell PostProcessor

JMeter has a Beanshell scripting extension mechanism which has access to all variables/properties in scope as well as to the underlying JMeter and 3rd-party dependencies APIs. In this case you can call JsonPath library (which is under the hood of JsonPath Extractor) directly from Beanshell PostProcessor.

import com.jayway.jsonpath.Criteria;
import com.jayway.jsonpath.Filter;
import com.jayway.jsonpath.JsonPath;

Object json = new String(data);
List categories = new ArrayList();
categories.add("fiction");
categories.add("reference");
Filter filter = Filter.filter(Criteria.where("category").in(categories));
List books = JsonPath.read(json, "$.store.book[?]", new Filter[] {filter});

vars.put("JSON_ARRAY_SIZE", String.valueOf(books.size()));

The code above evaluates JSONPath expression of $.store.book[?] against parent sampler response, counts matches number and stores it into ${JSON_ARRAY_SIZE} JMeter Variable

JSON Beanshell Variable

which can later be reused in an if clause or an assertion.

References:

edited Apr 30, 2019 at 14:20

gazzo

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answered Aug 28, 2014 at 8:29

Dmitri T

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3 Comments

David Over a year ago

Thanks for these suggestions! For now I'll use the quick solution with the Regular Expression Extractor, it's sufficient. But I'll probably use the BeanShell PostProcessor later. great :-)

UBIK LOAD PACK Over a year ago

Prefer the JSR223 + Groovy instead of Beanshell, way better for JMeter performances and way better for coding as Groovy is much more powerful for JSON and XML and maintained

Byte Commander Over a year ago

The first reference link (alexandru-ersenie.com) has expired.

UBIK LOAD PACK · Accepted Answer · 2019-02-08 23:38:18Z

0

This is not possible with the plugin you are using (JMeter-plugins).

But it can be done with JSON Extractor since JMeter 3.0, this plugin has been donated by UbikLoadPack (http://jmeter.apache.org/changes_history.html)

Example:

Say you have this JSON that contains an array of books:

   { "store": {"book": [
      { "category": "reference","author": "Nigel Rees","title":      "Sayings of the Century","price": 8.95},
      { "category": "fiction","author": "Evelyn Waugh","title": "Sword of Honour","price": 12.99},
      { "category": "fiction","author": "Herman Melville","title": "Moby Dick","isbn": "0-553-21311-3","price": 8.99},
      { "category": "fiction","author": "J. R. R. Tolkien","title": "The Lord of the Rings","isbn": "0-395-19395-8","price": 22.99}
   ],
    "bicycle": {"color": "red","price": 19.95}} }

To have this count:

1/ Add JSON Extractor:

The count will be then available bookTitle_matchNr which you can access through:

${bookTitle_matchNr}

Running this Test Plan would display this:

As you can see, Debug Sampler-${bookTitle_matchNr} shows Debug Sampler-4

edited Feb 8, 2019 at 23:38

answered Aug 27, 2014 at 14:25

UBIK LOAD PACK

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3 Comments

David Over a year ago

Thanks for the suggestion! Your plugin seems really useful, but for now I'll go with the Regular Expression Extractor solution that Dmitri mentioned. Thanks anyway!

UBIK LOAD PACK Over a year ago

No problem :-) , as Dmitri says, using Regexp for JSON is not usually a good thing, and Beanshell leads to lot of custom code and maintainability + productivity issues, in the end buying our plugin is better :-) , but if you go for coding , prefer the JSR223 + Groovy instead of Beanshell, Way better for JMeter performances and Way better for coding as Groovy is much more powerful and maintained

Adam Howell Nov 30, 2024 at 21:01

This answer should NOT be downvoted as it worked perfectly for me. And the JSON Extractor is no longer a plugin, but is now part of the release.

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