UnityWebRequest.downloadHandler.text is empty, eventhough the POST method returns a response - unity3d

Question

I am making a POST api call to my server using UnityWebRequest (Unity version that i have is 2017.4.0f1)
I am sending some data elements in the request body to the server, which
inserts into my DB and returns a response body, which is a json string
I am using
UnityWebRequest.downloadhandler.text to read the response message,
but it is empty, eventhough the data elements
are getting inserted into my DB. request.downloadHandler.data.Length also gives me 0
Making the same call through
Postman returns me the appropriate response (so does using
HTTPWebRequest and reading the response via a stream reader)
This is the code snippet that i have for it:
UnityWebRequest request=new UnityWebRequest(endpoint,"POST");
request.SetRequestHeader("Content-Type","application/json");
request.SetRequestHeader("host",host);
request.SetRequestHeader("X-Amz-Date",dateTime);
request.SetRequestHeader("Authorization",authorizationHeader);
request.uploadHandler=(UploadHandler)new
UploadHandlerRaw(Encoding.UTF8.GetBytes(requestParameter));
request.chunkedTransfer=false;
request.downloadHandler=new DownloadHandlerBuffer();
request.SendWebRequest();
print(request.downloadHandler.text);
Please advise as to what i am doing wrong here.....

Answer 1

You need to wait for the results to be downloaded before you can do anything with it. Webrequests are asynchronous!
Typically, you would use a Coroutine to do this, like
public IEnumerator LoadData()
{
// ......
// all your code goes here, up to the SendWebRequest line
// then you yield to wait for the request to return
yield return request.SendWebRequest();
// after this, you will have a result
print(request.downloadHandler.text);
}
Start this coroutine like this:
StartCoroutine(LoadData());
More examples in the answer to this question: Sending http requests in C# with Unity

Answer 2

As frankhermes says you need wait for the results to be downloaded before you do anything
yield return request.SendWebRequest();
But the above line alone didn't work for me.
public IEnumerator LoadData()
{
// ......
// all your code goes here, up to the SendWebRequest line
var asyncOperation = request.SendWebRequest();
while (!asyncOperation.isDone)
{
// wherever you want to show the progress:
float progress = request.downloadProgress;
Debug.Log("Loading " + progress);
yield return null;
}
while (!request.isDone)
yield return null; // this worked for me
// after this, you will have a result
print(request.downloadHandler.text);
}