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

arrayscountjmeterjsonpath

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?

Best Solution

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:

Related Solutions

Javascript – How to check if an array includes a value in JavaScript

Modern browsers have Array#includes, which does exactly that and is widely supported by everyone except IE:

console.log(['joe', 'jane', 'mary'].includes('jane')); //true

You can also use Array#indexOf, which is less direct, but doesn't require polyfills for outdated browsers.

console.log(['joe', 'jane', 'mary'].indexOf('jane') >= 0); //true

Many frameworks also offer similar methods:

jQuery: $.inArray(value, array, [fromIndex])
Underscore.js: _.contains(array, value) (also aliased as _.include and _.includes)
Dojo Toolkit: dojo.indexOf(array, value, [fromIndex, findLast])
Prototype: array.indexOf(value)
MooTools: array.indexOf(value)
MochiKit: findValue(array, value)
MS Ajax: array.indexOf(value)
Ext: Ext.Array.contains(array, value)
Lodash: _.includes(array, value, [from]) (is _.contains prior 4.0.0)
Ramda: R.includes(value, array)

Notice that some frameworks implement this as a function, while others add the function to the array prototype.

Javascript – How to append something to an array

Use the Array.prototype.push method to append values to the end of an array:

// initialize array
var arr = [
  "Hi",
  "Hello",
  "Bonjour"
];

// append new value to the array
arr.push("Hola");

console.log(arr);

You can use the push() function to append more than one value to an array in a single call:

// initialize array
var arr = ["Hi", "Hello", "Bonjour", "Hola"];

// append multiple values to the array
arr.push("Salut", "Hey");

// display all values
for (var i = 0; i < arr.length; i++) {
  console.log(arr[i]);
}

Update

If you want to add the items of one array to another array, you can use firstArray.concat(secondArray):

var arr = [
  "apple",
  "banana",
  "cherry"
];

arr = arr.concat([
  "dragonfruit",
  "elderberry",
  "fig"
]);

console.log(arr);

Update

Just an addition to this answer if you want to prepend any value to the start of an array (i.e. first index) then you can use Array.prototype.unshift for this purpose.

var arr = [1, 2, 3];
arr.unshift(0);
console.log(arr);

It also supports appending multiple values at once just like push.

Update

Another way with ES6 syntax is to return a new array with the spread syntax. This leaves the original array unchanged, but returns a new array with new items appended, compliant with the spirit of functional programming.

const arr = [
  "Hi",
  "Hello",
  "Bonjour",
];

const newArr = [
  ...arr,
  "Salut",
];

console.log(newArr);

Best Solution

Related Solutions

Javascript – How to check if an array includes a value in JavaScript

Javascript – How to append something to an array

Related Question