sending payload for post method in VBA - vba

Question

I'm trying to login to a website using VBA Excel, but I'm having trouble to send payload post method like in python request.
Example in python
def login():
s = requests.Session()
payload = {
'username':sett.username,
'password':sett.password1
}
res = s.post(link, json=payload)
ref_t = json.loads(res.content)['content']['refresh_token']
t = json.loads(res.content)['content']['token']
return t
this is what I've tried but fail:
Dim request As New WinHttpRequest
request.Open "POST", auth_url, False
auth = "username=" & user & "," & "password=" & pass
request.SetRequestHeader "content-type", "application/json;charset=UTF-8"
request.SetCredentials "username:" & user, "password:" & pass, 0
request.Send auth
If request.Status <> 200 Then
MsgBox request.ResponseText
Exit Sub
End If
the response text shows "Username is required, but was not received", "Password is required, but was not received", "code":400.
Edit:
Dim auth As New Dictionary
auth.Add "username", user
auth.Add "password", pass
request.Open "POST", auth_url, False
request.SetRequestHeader "content-type", "application/json"
request.Send JsonConverter.ConvertToJson(auth)

Answer 1

Turns out that I need to use SetRequestHeader
Edit:
Dim auth As New Dictionary
auth.Add "username", user
auth.Add "password", pass
request.Open "POST", auth_url, False
request.SetRequestHeader "content-type", "application/json"
request.Send JsonConverter.ConvertToJson(auth)