(Go) Square OAuth2 Access Token

Demonstrates how to get an access token for the Square API. This example is for desktop apps only (not web apps).

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

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

    oauth2 := chilkat.NewOAuth2()
    var success bool

    // This should be the port in the localhost callback URL for your app.  
    // The callback URL would look like "http://localhost:3017/" if the port number is 3017.
    oauth2.SetListenPort(3017)

    // To use the production system, change the domains here to "connect.squareup.com"
    oauth2.SetAuthorizationEndpoint("https://connect.squareupsandbox.com/oauth2/authorize")
    oauth2.SetTokenEndpoint("https://connect.squareupsandbox.com/oauth2/token")

    // Replace these with actual values.
    oauth2.SetClientId("APPLICATION_ID")
    oauth2.SetClientSecret("APPLICATION_SECRET")

    // Make sure to include the scopes you'll need.
    oauth2.SetScope("ITEMS_WRITE ITEMS_READ")

    // Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
    url := oauth2.StartAuth()
    if oauth2.LastMethodSuccess() != true {
        fmt.Println(oauth2.LastErrorText())
        oauth2.DisposeOAuth2()
        return
    }

    // Add the session=False query param to the URL.
    sbUrl := chilkat.NewStringBuilder()
    sbUrl.Append(*url)
    sbUrl.Append("&session=False")
    // Launch this URL in the browser.
    url = *sbUrl.GetAsString()

    // At this point, your application should load the URL in a browser.
    // For example, 
    // in C#: System.Diagnostics.Process.Start(url);
    // in Java: Desktop.getDesktop().browse(new URI(url));
    // in VBScript: Set wsh=WScript.CreateObject("WScript.Shell")
    //              wsh.Run url
    // in Xojo: ShowURL(url)  (see http://docs.xojo.com/index.php/ShowURL)
    // in Dataflex: Runprogram Background "c:\Program Files\Internet Explorer\iexplore.exe" sUrl        
    // The Microsoft account owner would interactively accept or deny the authorization request.

    // Add the code to load the url in a web browser here...
    // Add the code to load the url in a web browser here...
    // Add the code to load the url in a web browser here...

    // Now wait for the authorization.
    // We'll wait for a max of 30 seconds.
    numMsWaited := 0
    for (numMsWaited < 30000) && (oauth2.AuthFlowState() < 3) {
        oauth2.SleepMs(100)
        numMsWaited = numMsWaited + 100
    }

    // If there was no response from the browser within 30 seconds, then 
    // the AuthFlowState will be equal to 1 or 2.
    // 1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
    // 2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
    // In that case, cancel the background task started in the call to StartAuth.
    if oauth2.AuthFlowState() < 3 {
        oauth2.Cancel()
        fmt.Println("No response from the browser!")
        oauth2.DisposeOAuth2()
        sbUrl.DisposeStringBuilder()
        return
    }

    // Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
    // The possible AuthFlowState values are:
    // 3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
    // 4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
    // 5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
    if oauth2.AuthFlowState() == 5 {
        fmt.Println("OAuth2 failed to complete.")
        fmt.Println(oauth2.FailureInfo())
        oauth2.DisposeOAuth2()
        sbUrl.DisposeStringBuilder()
        return
    }

    if oauth2.AuthFlowState() == 4 {
        fmt.Println("OAuth2 authorization was denied.")
        fmt.Println(oauth2.AccessTokenResponse())
        oauth2.DisposeOAuth2()
        sbUrl.DisposeStringBuilder()
        return
    }

    if oauth2.AuthFlowState() != 3 {
        fmt.Println("Unexpected AuthFlowState:", oauth2.AuthFlowState())
        oauth2.DisposeOAuth2()
        sbUrl.DisposeStringBuilder()
        return
    }

    fmt.Println("OAuth2 authorization granted!")
    fmt.Println("Access Token = ", oauth2.AccessToken())

    // Get the full JSON response:
    json := chilkat.NewJsonObject()
    json.Load(oauth2.AccessTokenResponse())
    json.SetEmitCompact(false)

    // The JSON response looks like this:

    // {
    //   "access_token": "EAAAE...depV",
    //   "token_type": "bearer",
    //   "expires_at": "2020-09-04T23:30:18Z",
    //   "merchant_id": "MLQA83866KSR5",
    //   "refresh_token": "EQAAEE...jeVfD6MV"
    // }

    fmt.Println(*json.Emit())

    // Save the JSON to a file for future requests.
    fac := chilkat.NewFileAccess()
    fac.WriteEntireTextFile("qa_data/tokens/square.json",*json.Emit(),"utf-8",false)

    oauth2.DisposeOAuth2()
    sbUrl.DisposeStringBuilder()
    json.DisposeJsonObject()
    fac.DisposeFileAccess()