Pre-request async code doesn't wait for execution

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1

Hi,

One of my requirement is to call an async login API as a pre-request script in Postman windows client. Through this code I want to set the collection variable (jwt-token). The problem is that Postman doesn’t wait for the completion of the pre-request call and hence the actual request is throwing an error of ‘Un-authorized access’.

Below is the code:

(async ()=>{
const loginRequest = {
method: ‘POST’,
url: pm.collectionVariables.get(“loginUrl”),
header: {
‘Content-Type’: ‘application/json’
},
body:{
mode:‘raw’,
raw: JSON.stringify({ email: “”, password: “”})
}
}
await pm.sendRequest(loginRequest,(error, response)=>{
pm.collectionVariables.set(“jwt-token”, response.token)
})
})()

2

Hey @ahussain.ned , welcome to the Postman community!

I’d recommend having a look at this collection, it has examples of different ways to handle async operations and making sure things execute before the request goes through:
https://www.postman.com/postman/workspace/postman-answers/documentation/3407886-220af2f6-63f2-4d84-903d-99e6e296a8c8

You can also fork the collection and try it out for yourself.

3

Late, but since no one actually answered your question I’ll go ahead as I just got done feeling your pain.

The problem here is for whatever reason pm.sendRequest returns a function rather than a Promise.

The execution environment does have a scan that detects top-level Promises though, so the solution is to wrap your async work in a Promise and call the resolve function like you would a termination signal in older unit testing frameworks:

new Promise((res) => pm.sendRequest(
  {... your config },
  (err, res) => {
      ... your code
     res()
  }
))

The documentation, DX, ergonomics around scripting and automation in this product could definitely use some love.