(VB.NET) Dropbox Refresh OAuth2 Access Token

See more Dropbox Examples

Demonstrates how to mint a new access token using the refresh token obtained when originally getting the OAuth2 access token.

For more information, see https://www.dropbox.com/developers/documentation/http/documentation

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim http As New Chilkat.Http
Dim success As Boolean

' Implements the following CURL command:

' curl -X GET https://api.dropbox.com/oauth2/token \
'     -d grant_type=refresh_token \
'     -d refresh_token=<YOUR_REFRESH_TOKEN> \
'     -u <YOUR_APP_KEY>:<YOUR_APP_SECRET>

' Use the following online tool to generate HTTP code from a CURL command
' Convert a cURL Command to HTTP Source Code

http.Login = "DROPBOX_APP_KEY"
http.Password = "DROPBOX_APP_SECRET"

' Get the refresh token from the JSON we saved when originally getting the access token.
' (See Get Dropbox OAuth2 Access Token w/ Refresh Token
Dim json As New Chilkat.JsonObject
success = json.LoadFile("qa_data/tokens/dropbox.json")
If (success = False) Then
    Debug.WriteLine(json.LastErrorText)
    Exit Sub
End If


Dim req As New Chilkat.HttpRequest
req.AddParam("grant_type","refresh_token")
req.AddParam("refresh_token",json.StringOf("refresh_token"))

Dim resp As Chilkat.HttpResponse = http.PostUrlEncoded("https://api.dropbox.com/oauth2/token",req)
If (http.LastMethodSuccess = False) Then
    Debug.WriteLine(http.LastErrorText)
    Exit Sub
End If


Dim sbResponseBody As New Chilkat.StringBuilder
resp.GetBodySb(sbResponseBody)

Dim jResp As New Chilkat.JsonObject
jResp.LoadSb(sbResponseBody)
jResp.EmitCompact = False

Debug.WriteLine("Response Body:")
Debug.WriteLine(jResp.Emit())

Dim respStatusCode As Integer = resp.StatusCode
Debug.WriteLine("Response Status Code = " & respStatusCode)
If (respStatusCode >= 400) Then
    Debug.WriteLine("Response Header:")
    Debug.WriteLine(resp.Header)
    Debug.WriteLine("Failed.")

    Exit Sub
End If



' Sample JSON response:
' (Sample code for parsing the JSON response is shown below)

' {
'   "access_token": "sl.AC75WPYRqOi0mxcRqlimbV9FKHu04biz5qHwatG3MTgzFK7kLrGVlM9EgP4603tE7bWw0s1rMbTKiHsf37TUshPYvq-3r0qeBr_PrZIAibN8XOQicvboiOnqx6JrDekq-w8D-tE",
'   "token_type": "bearer",
'   "expires_in": 14400
' }

Dim access_token As String = jResp.StringOf("access_token")
Debug.WriteLine("New Access Token: " & access_token)


' Perhaps update our Dropbox JSON file with the new access token.
' (The existing refresh token does not change, and can be used over and over to mint new access tokens.)
json.UpdateString("access_token",access_token)

json.WriteFile("qa_data/tokens/dropbox.json")