B4X
USPS OAuth2 Client Credentials

Get an OAuth2 access token for the United States Postal Service (USPS) REST API.
Chilkat B4X Downloads

B4X
Dim success As Boolean = False

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

Dim http As ChilkatHttp
http.Initialize("http")

'  Implements the following CURL command:

'  curl -X POST https://apis.usps.com/oauth2/v3/token \
'    -H "Content-Type: application/x-www-form-urlencoded" \
'    -d "grant_type=client_credentials" \
'    -d "client_id=123456789" \
'    -d "client_secret=A1B2C3D4E5" \
'    -d "scope=ResourceA+ResourceB+ResourceC"

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

Dim req As ChilkatHttpRequest
req.Initialize
req.AddParam("grant_type", "client_credentials")
req.AddParam("client_id", "123456789")
req.AddParam("client_secret", "A1B2C3D4E5")
req.AddParam("scope", "ResourceA+ResourceB+ResourceC")

req.HttpVerb = "POST"
req.ContentType = "application/x-www-form-urlencoded"

Dim resp As ChilkatHttpResponse
resp.Initialize
success = http.HttpReq("https://apis.usps.com/oauth2/v3/token", req, resp)
If success = False Then
    Log(http.LastErrorText)
    Return
End If


Dim sbResponseBody As ChilkatStringBuilder
sbResponseBody.Initialize
resp.GetBodySb(sbResponseBody)

Dim jResp As ChilkatJsonObject
jResp.Initialize
jResp.LoadSb(sbResponseBody)
jResp.EmitCompact = False

Log("Response Body:")
Log(jResp.Emit)

Dim respStatusCode As Int = resp.StatusCode
Log("Response Status Code = " & respStatusCode)
If respStatusCode >= 400 Then
    Log("Response Header:")
    Log(resp.Header)
    Log("Failed.")
    Return
End If


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

'  {
'    "access_token": "eyJraWQiOiIxMDEwMTAiLCJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiIiLCJhdWQiOiJhZGRyZXNzZXMgaW50ZXJuYXRpb25hbC1wcmljZXMgc3Vic2NyaXB0aW9ucyBwYXltZW50cyBwaWNrdXAgdHJhY2tpbmcgbGFiZWxzIHNjYW4tZm9ybXMgY29tcGFuaWVzIHNlcnZpY2UtZGVsaXZlcnktc3RhbmRhcmRzIGxvY2F0aW9ucyBpbnRlcm5hdGlvbmFsLWxhYmVscyBwcmljZXMiLCJhenAiOiJoeXI3YjN2Q1J0cFl0QUhNMWE4Y2RVcmt5eUZtTmtiZyIsIm9yZ2FuaXphdGlvbl9pZCI6IjAiLCJpc3MiOiJ1cm46XC9cL2FwaS51c3BzLmNvbSIsImV4cCI6MTY4MDkxNzc4NiwiaWF0IjoxNjgwODg4OTg2LCJqdGkiOiI3YjU5MzJlMS05NjIxLTQzZDAtYTMyNy0xMzIxYWVjNzJjZGYifQ.QzrUxlT2rG4jvYbMDGnk23j8ZYfHJcdXPKR9CbSmcKeVpURaHhEMpPB6K4x5ut3xxeEGSzeE5VRz8vixI4iqyHsD8rSdkLTPHy0iovUHOZQBAJVQ6hii9jpLhxUXmiTtH3jKzSj_f2fuNmZbIGhf-CR2FBeWF-aBPzEDEMV95nkCUMfW_Z2BmkbraSfvQZxkCO-cLrMAwlYcrzUtaJ7vnazeQB4sep5BBHBEvsa4kfq6_tz6BAKgv3R7cI2NkSv-wgy_IGoTjVCMTS8mJHGs_t8cWCO8-z4lxW1tUwIBKOCUDpmEEnGgiG6Sl0C_gGl4bZ5cDSl4IgPpcOVi9jZ7LA",
'    "token_type": "Bearer",
'    "issued_at": 1680888985929,
'    "expires_in": 28799,
'    "status": "approved",
'    "scope": "addresses international-prices subscriptions payments pickup tracking labels scan-forms companies service-delivery-standards locations international-labels prices",
'    "issuer": "api.usps.com",
'    "client_id": "hyr7b3vCRtpYtAHM1a8cdUrkyyFmNkbg",
'    "application_name": "Silver Shipper Developer",
'    "api_products": "[Shipping-Silver]",
'    "public_key": "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"
'  }

'  Sample code for parsing the JSON response...
'  Use the following online tool to generate parsing code from sample JSON:
'  Generate Parsing Code from JSON



Dim access_token As String = jResp.StringOf("access_token")
Dim token_type As String = jResp.StringOf("token_type")
Dim issued_at As Int = jResp.IntOf("issued_at")
Dim expires_in As Int = jResp.IntOf("expires_in")
Dim status As String = jResp.StringOf("status")
Dim scope As String = jResp.StringOf("scope")
Dim issuer As String = jResp.StringOf("issuer")
Dim client_id As String = jResp.StringOf("client_id")
Dim application_name As String = jResp.StringOf("application_name")
Dim api_products As String = jResp.StringOf("api_products")
Dim public_key As String = jResp.StringOf("public_key")