Extract nested JSON array response object using JS Lodash in Postman - json

Question

I want to learn how to use Lodash to extract variables from a JSON response because the traditional methods explained on other Postman questions do not explain an easy way to do this as I used to do it with json path in Jmeter.
I need to translate the following json paths to a Lodash expression that returns the same values as this JSON paths
1. FlightSegmentsItinerary[*].Flights[*].Key
2. $..Flights[*].Key
3. Travelers[*].[?(#.TypeCode == "INF")].FirstName (returns the name of the passangers whose type code are == "INF")
JSON Response:
{
"Travelers": [
{
"TypeCode": "ADT",
"FirstName": "FULANO",
"Surname": "LAZARO",
"Key": "1.1"
},
{
"TypeCode": "INF",
"FirstName": "MENGANO",
"Surname": "XULO",
"Key": "2.2"
}
],
"FlightSegmentsItinerary": [
{
"Flights": [
{
"Key": "1"
},
{
"Key": "2"
}
]
}
]
}
So far I was able to extract the travelers Keys (Travelers[*].Key) using this:
var jsonData = pm.response.json();
var travelerKeys = _.map(jsonData.Travelers, 'Key');
console.log("travelerKeys: " + travelerKeys);
Output: travelerKeys: 1.1,2.2
As you can see, the JSON path:
Travelers[*].Key
Looks like this in Lodash:
var travelerKeys = _.map(jsonData.Travelers, 'Key');
for this case.

Answer 1

var jsonData = {
"Travelers": [{
"TypeCode": "ADT",
"FirstName": "FULANO",
"Surname": "LAZARO",
"Key": "1.1"
},
{
"TypeCode": "INF",
"FirstName": "MENGANO",
"Surname": "XULO",
"Key": "2.2"
}
],
"FlightSegmentsItinerary": [{
"Flights": [{
"Key": "1"
},
{
"Key": "2"
}
]
}]
}
// 1. FlightSegmentsItinerary[*].Flights[*].Key
console.log( _(jsonData.FlightSegmentsItinerary).flatMap('Flights').map('Key') )
//2. $..Flights[*].Key
console.log( _.chain(jsonData).values().flatten().find('Flights').values().flatten().map('Key') )
//3. Travelers[*].[?(#.TypeCode == "INF")].FirstName (returns the name of the passangers whose type code are == "INF")
console.log( _(jsonData.Travelers).filter(['TypeCode', 'INF']).map('FirstName') )
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.11/lodash.min.js"></script>
Another option might be to try JavaScript libraries such as https://github.com/dchester/jsonpath
var jsonData = {
"Travelers": [{
"TypeCode": "ADT",
"FirstName": "FULANO",
"Surname": "LAZARO",
"Key": "1.1"
},
{
"TypeCode": "INF",
"FirstName": "MENGANO",
"Surname": "XULO",
"Key": "2.2"
}
],
"FlightSegmentsItinerary": [{
"Flights": [{
"Key": "1"
},
{
"Key": "2"
}
]
}]
}
console.log(jsonpath.query(jsonData, '$.FlightSegmentsItinerary[*].Flights[*].Key'))
console.log(jsonpath.query(jsonData, '$..Flights[*].Key'))
console.log(jsonpath.query(jsonData, '$.Travelers..[?(#.TypeCode == "INF")].FirstName'))
<script src="https://cdn.jsdelivr.net/npm/jsonpath#1.0.2/jsonpath.min.js"></script>
Because Postman doesn't support fetch and XMLHttpRequest, the jsonpath.min.js file contents can be saved in environment variable, and then eval(pm.environment.get('jsonpath')); before use as described in
https://community.getpostman.com/t/adding-external-libraries-to-postman/1971/4

Answer 2

You have to tell Postman which Sandbox module you going to use using require function(refer below code). The error you get has some issue with Postman few of them works few of them not Here they are talking
and Here is the postman issue tracker
the code I tried and worked for me as
const moment = require('lodash');
var keys = _.chain(obj.Travelers)
.map("Key")
.flatten()
.unique()
.value();
console.log(keys);
output
Array:[]
0 : "1.1"
1 : "2.2"
form more details you can look at
Postman Sandbox API reference
postman-and-lodash-the-perfect-partnership