How to create Encrypted PayNow button “on the fly” for Third-party customers, using Paypal NVP API?

Question

I need to create Encrypted \"PayNow\" paypal buttons on the fly for a website.
I read all the documentation I can find on the paypal website.
I understood that I nee

Answer 1

Ok, finally I got it! :-)

My objective is to create Encrypted PayNow buttons "on the fly" for some of our customers. Here is a brief explanation of how PayPal API works with Third-party access.

• Create a Paypal Sandbox account (here)
• In this sandbox account, create 2 new business account
  you should hook these business account to a credit card. This will mark these account as "verified", unless it won't work
  • The first account (account A) will represent our company
  • The second account (account B) will represent one of our customers
• log in account A, and request the API credentials (instructions here)
• log in account B, and grant API permission to account A (instruction here check the paragraph "Third-party authentication: Grant your cart the appropriate API authentication permissions")
• grab the Api credentials of account A, and put them in your source code
• grab Merchant ID and merchant Email of account B and put them in your source code
• run the code
• grab the returned html, put it on a web page, and test it, it should works
  (you need to be logged on your paypal sandbox account, or the generated button wont works)

Why this simple and concise knowledge is timewastingly scattered among a countless number of PayPal help pages, PayPal PDF manuals, and third party blog post, is beyond my understanding :-) Anyway...

Here is the working code in VB.Net

Public Shared Sub PaypalThirdPartyPayNowButtonTest()
    Dim bvCount As Integer = 0  ''L_BUTTONVAR counter
    Dim NVP As New Dictionary(Of String, String)  ''Api Name-Value-Pair parameters

    ''define paypal SANDBOX server
    Dim paypalApiServerUrl As String = "https://api-3t.sandbox.paypal.com/nvp"

    ''define Api credentials of YOUR business paypal account 
    Dim yourApiUsername As String = "aso_1273063882_biz_api3.megatesto.it"
    Dim yourApiPassword As String = "1273063582"
    Dim yourApiSignature As String = "A22sd7623RGUsduDHDSFU57N7dfhfS23DUYVhdf85du8S6FJ6D5bfoh5"

    ''define Your CUSTOMER identification data
    Dim customerEmailID As String = "MyCustomer_143363961_biz@megatesto.it"
    Dim customerMerchantID As String = "3S4EF7BI96YHS"


    ''use YOUR identification data
    NVP.Add("USER", yourApiUsername)
    NVP.Add("PWD", yourApiPassword)
    NVP.Add("SIGNATURE", yourApiSignature)

    ''use your CUSTOMER identification data
    NVP.Add("SUBJECT", customerEmailID)
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "business=" & customerMerchantID) ''Merchant ID


    ''Api method name and version
    NVP.Add("METHOD", "BMCreateButton")
    NVP.Add("VERSION", "85.0")

    ''method specific parameters
    NVP.Add("BUTTONCODE", "ENCRYPTED")
    NVP.Add("BUTTONTYPE", "BUYNOW")
    NVP.Add("BUTTONSUBTYPE", "PRODUCTS")

    ''Buynow button specific parameters
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "lc=IT")
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "button_subtype=PRODUCTS")
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "item_name=Test_product")
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "item_number=123456")
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "amount=12.00")
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "currency_code=EUR")
    bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "quantity=1")
    ''bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "cmd=_s-xclick")  'DONT' specify the cmd parameter, if you specify it, it wont work, paypal will give you an error

    ''build the parameter string
    Dim paramBuilder As New StringBuilder
    For Each kv As KeyValuePair(Of String, String) In NVP
        Dim st As String
        st = kv.Key & "=" & HttpUtility.UrlEncode(kv.Value) & "&"
        paramBuilder.Append(st)
    Next

    Dim param As String
    param = paramBuilder.ToString
    param = param.Substring(0, param.Length - 1) ''remove the last '&'


    ''Create web request and web response objects, make sure you using the correct server (sandbox/live)
    Dim wrWebRequest As HttpWebRequest = DirectCast(WebRequest.Create(paypalApiServerUrl), HttpWebRequest)
    wrWebRequest.Method = "POST"


    Dim requestWriter As New StreamWriter(wrWebRequest.GetRequestStream())
    requestWriter.Write(param)
    requestWriter.Close()

    '' Get the responseReader
    Dim responseReader As StreamReader
    responseReader = New StreamReader(wrWebRequest.GetResponse().GetResponseStream())

    ''read the response
    Dim responseData As String
    responseData = responseReader.ReadToEnd()
    responseReader.Close()


    ''url-decode the results
    Dim result As String
    result = HttpUtility.UrlDecode(responseData)

    Dim formattedResult As String

    formattedResult = "Request on " & paypalApiServerUrl & vbCrLf &
                     HttpUtility.UrlDecode(param.Replace("&", vbCrLf & "  ")) & vbCrLf & vbCrLf &
                     "Result:" & vbCrLf & HttpUtility.UrlDecode(responseData.Replace("&", vbCrLf & "  ")) & vbCrLf & vbCrLf &
                     "--------------------------------------" & vbCrLf

    ''show the results
    Trace.WriteLine(formattedResult)
    MessageBox.Show(formattedResult)
End Sub

And here is the same code in C#

public static void PaypalThirdPartyPayNowButtonTest()
{
    int bvCount = 0; //L_BUTTONVAR counter
    Dictionary<string, string> NVP = new Dictionary<string, string>(); //Api Name-Value-Pair parameters

    //paypal SANDBOX server
    string paypalApiServerUrl = "https://api-3t.sandbox.paypal.com/nvp";

    //Api credentials of YOUR business paypal account 
    string yourApiUsername = "aso_1273063882_biz_api3.megatesto.it";
    string yourApiPassword = "1273063582";
    string yourApiSignature = "A22sd7623RGUsduDHDSFU57N7dfhfS23DUYVhdf85du8S6FJ6D5bfoh5";

    //Your CUSTOMER identification data
    string customerEmailID = "MyCustomer_143363961_biz@megatesto.it";
    string customerMerchantID = "3S4EF7BI96YHS";

    //use YOUR identification data
    NVP.Add("USER", yourApiUsername);
    NVP.Add("PWD", yourApiPassword);
    NVP.Add("SIGNATURE", yourApiSignature);

    //use your CUSTOMER identification data
    NVP.Add("SUBJECT", customerEmailID);
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "business=" + customerMerchantID);

    //Api method name and version
    NVP.Add("METHOD", "BMCreateButton");
    NVP.Add("VERSION", "85.0");

    //method specific parameters
    NVP.Add("BUTTONCODE", "ENCRYPTED");
    NVP.Add("BUTTONTYPE", "BUYNOW");
    NVP.Add("BUTTONSUBTYPE", "PRODUCTS");

    //Buynow button specific parameters
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "lc=IT");
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "button_subtype=PRODUCTS");
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "item_name=Test_product");
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "item_number=123456");
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "amount=12.00");
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "currency_code=EUR");
    bvCount++; NVP.Add("L_BUTTONVAR" + bvCount.ToString() , "quantity=1");
    //bvCount = bvCount + 1 : NVP.Add("L_BUTTONVAR" & bvCount, "cmd=_s-xclick")  //DON'T specify the cmd parameter, if you specify it, it wont work, paypal will give you an error


    //build the parameter string
    StringBuilder paramBuilder = new StringBuilder();
    foreach (KeyValuePair<string, string> kv in NVP)
    {
        string st = kv.Key + "=" + System.Web.HttpUtility.UrlEncode(kv.Value) + "&";
        paramBuilder.Append(st);
    }

    string param = paramBuilder.ToString();
    param = param.Substring(0, param.Length - 1); //remove the last '&'


    //Create web request and web response objects, make sure you using the correct server (sandbox/live)
    System.Net.HttpWebRequest wrWebRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(paypalApiServerUrl);
    wrWebRequest.Method = "POST";

    System.IO.StreamWriter requestWriter = new System.IO.StreamWriter(wrWebRequest.GetRequestStream());
    requestWriter.Write(param);
    requestWriter.Close();


    //Get the responseReader
    System.IO.StreamReader responseReader = new System.IO.StreamReader(wrWebRequest.GetResponse().GetResponseStream());
    string responseData = responseReader.ReadToEnd();
    responseReader.Close();

    //url-decode the results
    string result = System.Web.HttpUtility.UrlDecode(responseData);

    string formattedResult = "Request on " + paypalApiServerUrl + "\r\n" + System.Web.HttpUtility.UrlDecode(param.Replace("&", "\r\n  ")) + "\r\n\r\nResult:\r\n" + System.Web.HttpUtility.UrlDecode(responseData.Replace("&", "\r\n  ")) + "\r\n\r\n--------------------------------------\r\n";

    //show the results
    System.Diagnostics.Trace.WriteLine(formattedResult);
    System.Windows.Forms.MessageBox.Show(formattedResult);
}

I wish everyone a happy PayPal integration :-)

Update (for PHP coder)
@Style is asking for a working PHP example... I don't know PHP, but I've found some links that may contain useful information for PHP coder,: you can look for BMCreateButton api inside these source files:

• PayPal "Authorization Failed"
• Working example of paypal Website Payments Pro Hosted Solution Iframe?
• http://code.google.com/p/my-project-phi/source/browse/trunk/Application/Services/PayPalService.php?r=61
• http://plugins.svn.wordpress.org/stageshow/tags/1.1.4/include/mjslib_paypal_api.php
• http://plugins.svn.wordpress.org/stageshow/trunk/include/mjslib_paypal_api.php
• http://my-project-phi.googlecode.com/svn-history/r61/trunk/Application/Services/PayPalService.php