How to create a collection variable from response in postman - postman

Question

Selecting a value and right-clicking enables me to save it as a Global variable.
But there is no option to save it as a collection variable.
In the environments section as well. I can see Globals but my collection is not available.
But as I go through blogs/ articles online I can see some variables that are scoped to a collection.
Can I know a way to achieve this?

Answer 1

Tests tab is all you need
Considering the Stackoverflow GetUser API for Reference.
NOTE: The below-shown response is a part of the original response.
Response:
{
"items": [
{
"user_type": "registered",
"user_id": 12345678,
}
]
}
In the above response let's say we need user_type, and user_id in another API's URL / body / headers.
Before accessing we need to store these variables after receiving the response. This can be done in the Tests tab in postman request.
const jsonData = JSON.parse(responseBody);
const userType = jsonData?.items?.[0]?.user_type;
const userId = jsonData?.items?.[0]?.user_id;
if(userType){
pm.collectionVariables.set("userType",userType)
}
if(userId){
pm.collectionVariables.set("userId", userId)
}
Points to Note:
Postman tests are written in Javascript.
Optional chaining in line 2,3 is to avoid console errors. Possible Scenario: When API fails and returns an error response.
The IF Statements are to avoid null values in case of an Error Response. If statements are not mandatory. In fact without using if statements you will get to know clearly that something went wrong.
How to use collection variables
Once you make a request with the above tests. Postman IntelliSense suggests available collection variables. ( Refer to the image attached )
We are sending the body as a raw JSON in this Test Endpoint. Note that userType is surrounded by double quotes "" whereas userId is not. ( JSON syntax )