How can I count array elements in Postman tests

Question

I have a json response like this and I would like to count how many Friend Groups are in MyFriends array (in my case I expect the code to return 7) :

I tried following but it throws tis error--

TypeError: Cannot read properties of undefined (reading '0')

var data = pm.response.json().MyFriends[0].FriendGroupProperties;

pm.test('Number of friends = ' + MyFriends.length, function () {
    pm.expect(data.length).to.equal(7);
});

I also tried this but it also throws

TypeError: Cannot convert undefined or null to object

error :

var data = pm.response.json().MyFriends;

var count = Object.keys(data).length;

console.log("The number of expected friends in the response body is: " + count);

console.log(`Number of Friends: ${_.size(data)}`)

Is there anyone who can help me with this?

Answer 1

Your data is array data (start [ and end ]) in your body.

It has single item of array, and MyFriends is first field , then it has 7 items of array.

You can add console log(print) step by step as I added in my code.

Also console output(left bottom side of UI) help to debug and can get the correct data position and length as I attached image.

Using this test code

var jsonData = JSON.parse(responseBody);
console.log(jsonData.length)
console.log(jsonData[0])
console.log(jsonData[0].MyFriends)
console.log(jsonData[0].MyFriends.length)

pm.test('Number of friends = ' + jsonData[0].MyFriends.length, function () {
    pm.expect(jsonData[0].MyFriends.length).to.equal(7);
});

It is screen of Postman

Test Result

This is online console