Category: asp.net

OK, here’s another REST API example. In the same system I blogged about yesterday, I also had to use the Mandrill API to send out some transactional emails. Mandrill is a relatively new service from MailChimp that can be used to send out e-mail via simple API calls. It’s pretty nice, and free to use, up to a certain point.

You can actually use it via regular old SMTP, with some control info added into the headers, or you can go ahead and use their REST API. I decided to use the API. Initially, I had no luck with that at all. After thrashing around a bit, I eventually figured out that I had to update to the newest version of EasyHttp. Then, it started working fine, no problem. I didn’t bother looking into the internals of EasyHttp to try and figure out what was causing the problem. I’m kind of curious, but, as usual, it’s more important to just get the thing working.

So, here’s another Gist with some code:

/*
 * Code/Mandrill.cs
 * These are calls to the Mandrill email service.
 * Reference: https://mandrillapp.com/api/docs/
 * 
 * ajh 2012-08-09: new
 */
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Configuration;
using System.Dynamic;
using EasyHttp.Http;
using System.Net;
using log4net;

namespace Sample.Web
{
    enum MandrillError
    {
        OK,
        WebException,
        HttpNotOk,
        Invalid,
        Rejected,
        Unknown
    }

    public class Mandrill
    {
        static string MandrillBaseUrl = ConfigurationManager.AppSettings["MandrillBaseUrl"];
        static Guid MandrillKey = new Guid(ConfigurationManager.AppSettings["MandrillKey"]);

        public static bool SendActivationEMail(BLL.TrialSignup ts, out string errorMsg)
        {
            string activationLink =
                HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Authority) + "/Register/Activation.aspx?id=" + ts.Id;
            
            //send-template(string key, string template_name, array template_content, struct message) 
            dynamic sendParams = new ExpandoObject();
            sendParams.key = MandrillKey;
            sendParams.template_name = "Secret Project Trial Activation";

            sendParams.template_content = new List();
            
            sendParams.message = new ExpandoObject();
            sendParams.message.subject = "Here's your Secret Project activation email";
            sendParams.message.from_email = "info@SecretProject.com";
            sendParams.message.from_name = "Secret Project";

            sendParams.message.to = new List();
            sendParams.message.to.Add(new ExpandoObject());
            sendParams.message.to[0].email = ts.EMail;
            sendParams.message.to[0].name = ts.Name;

            sendParams.message.track_opens = true;
            //sendParams.message.track_clicks = true;

            sendParams.message.global_merge_vars = new List();
            sendParams.message.global_merge_vars.Add(new ExpandoObject());
            sendParams.message.global_merge_vars[0].name = "NAME";
            sendParams.message.global_merge_vars[0].content = ts.Name;

            sendParams.message.global_merge_vars.Add(new ExpandoObject());
            sendParams.message.global_merge_vars[1].name = "LINK";
            sendParams.message.global_merge_vars[1].content = activationLink;

            errorMsg = string.Empty;
            
            MandrillError merr = SendMessage(sendParams);

            switch (merr)
            {
                case MandrillError.OK:
                    return true;
                case MandrillError.WebException:
                case MandrillError.HttpNotOk:
                    errorMsg = "There was an issue sending your activation e-mail. Please try again later or call us directly.";
                    break;
                case MandrillError.Invalid:
                    errorMsg = "Your email address appears to be invalid. Please try again with a valid address, or call us directly.";
                    break;
                case MandrillError.Rejected:
                    errorMsg = "Your activation email was rejected. Please try again with a valid address, or call us directly.";
                    break;
                case MandrillError.Unknown:
                    errorMsg = "There was an unknown problem sending your activation email. Please try again, or call us directly.";
                    break;
            }
            return false;
        }

        public static bool SendSalesNotification(BLL.TrialSignup ts)
        {
            dynamic sendParams = new ExpandoObject();
            sendParams.key = MandrillKey;
            sendParams.template_name = "Secret Project Trial Sales Notification";

            sendParams.template_content = new List();

            sendParams.message = new ExpandoObject();
            sendParams.message.subject = "Secret Project Trial Account Notification";
            sendParams.message.from_email = "info@SecretProject.com";
            sendParams.message.from_name = "Secret Project";

            sendParams.message.to = new List();
            sendParams.message.to.Add(new ExpandoObject());
            sendParams.message.to[0].email = ConfigurationManager.AppSettings["SalesEmail"];
            sendParams.message.to[0].name = "Secret Project Sales";

            //sendParams.message.track_opens = true;
            //sendParams.message.track_clicks = true;

            sendParams.message.global_merge_vars = new List();
            sendParams.message.global_merge_vars.Add(new ExpandoObject());
            sendParams.message.global_merge_vars[0].name = "NAME";
            sendParams.message.global_merge_vars[0].content = ts.Name;

            sendParams.message.global_merge_vars.Add(new ExpandoObject());
            sendParams.message.global_merge_vars[1].name = "COMPANY";
            sendParams.message.global_merge_vars[1].content = ts.CompanyName;
            
            sendParams.message.global_merge_vars.Add(new ExpandoObject());
            sendParams.message.global_merge_vars[2].name = "EMAIL";
            sendParams.message.global_merge_vars[2].content = ts.EMail;

            MandrillError merr = SendMessage(sendParams);

            switch (merr)
            {
                case MandrillError.OK:
                    return true;
                case MandrillError.WebException:
                case MandrillError.HttpNotOk:
                case MandrillError.Invalid:
                case MandrillError.Rejected:
                case MandrillError.Unknown:
                    break;
            }
            return false;
        }

        private static MandrillError SendMessage(dynamic sendParams)
        {
            ILog _log = log4net.LogManager.GetLogger("Mandrill/SendMessage");

            string url = MandrillBaseUrl + "/messages/send-template.json";

            var http = new HttpClient
            {
                Request = { Accept = HttpContentTypes.ApplicationJson }
            };

            EasyHttp.Http.HttpResponse response;
            try
            {
                response = http.Post(url, sendParams, HttpContentTypes.ApplicationJson);
            }
            catch (WebException ex)
            {
                _log.ErrorFormat("Error: WebException - {0}", ex.Message);
                return MandrillError.WebException;
            }

            if (response.StatusCode != HttpStatusCode.OK)
            {
                _log.InfoFormat("Response = {0} - {1}", response.StatusCode, response.StatusDescription);
                _log.Info(response.RawText);
                return MandrillError.HttpNotOk;
            }

            dynamic rv = response.DynamicBody;
            _log.InfoFormat("email: {0}, status: {1}", rv[0].email, rv[0].status);

            string send_status = rv[0].status;
            if (send_status == "sent" || send_status == "queued")
                return MandrillError.OK;

            // otherwise, it should be "rejected" or "invalid"
            if (send_status == "invalid")
            {
                return MandrillError.Invalid;
            }
            if (send_status == "rejected")
            {
                return MandrillError.Rejected;
            }

            // unexpected...
            return MandrillError.Unknown;
        }
        
    }
}

I hope someone finds it useful and/or entertaining.
In this code, I’m sending out two e-mails, one is a trial account activation email, and the other is just a notification to sales. On the first, I’m looking at the errors closely and trying to return a useful error message, so the customer knows that something has gone wrong and has a clue about how to handle it. On the second, I’m less worried about that, as it’s just a notification to our salesperson.

I have about a dozen programming-related items floating around in my head that I’d like to write up short blog entries about. Maybe I’ll manage to get one or two written up tonight.

I’ve been doing some work recently with some random REST APIs. When I’m calling REST APIs from .NET, I like to use EasyHttp. Based on the stats on its NuGet page, I guess it’s not that popular, but it’s updated often enough, and it works well for me.

I recently worked on a project where I had to create a lead in Zoho CRM, using their API. I had a little bit of trouble, but only because I didn’t have quite the right parameters set — it turns out that “newformat=1” is really important. I had looked for some sample C# code for the Zoho API when I started this, and didn’t find any, so I thought I’d post a quick Gist with my code:

/*
 * Sample C# code to create a lead with the Zoho CRM API.
 * ajh 2012-08-23
 */
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Dynamic;
using System.Linq;
using System.Net;
using System.Web;
using System.Xml;
using System.Xml.Linq;
using EasyHttp.Http;
using log4net;

namespace Sample.Web
{
    public class ZohoCrm
    {
        static string ZohoApiBaseUrl = "https://crm.zoho.com/crm/private/xml/Leads/insertRecords"; 
        static string ZohoApiKey = ConfigurationManager.AppSettings["ZohoApiKey"];

        public static bool CreateLead(BLL.SampleLead sl)
        {
            ILog _log = log4net.LogManager.GetLogger("ZohoCrm/CreateLead");

            XDocument xmlData = new XDocument(
            new XElement("Leads",
                new XElement("row", new XAttribute("no", "1"),
                    new XElement("FL", new XAttribute("val", "Lead Source"), "Trial Signup"),
                    new XElement("FL", new XAttribute("val", "Company"), sl.CompanyName),
                    new XElement("FL", new XAttribute("val", "Last Name"), sl.Name),
                    new XElement("FL", new XAttribute("val", "Email"), sl.EMail)
                )));

            string url = string.Format("{0}?authtoken={1}&scope=crmapi&newFormat=1&xmlData={2}", 
				ZohoApiBaseUrl, ZohoApiKey, 
                HttpUtility.UrlEncode(xmlData.ToString()));

            var http = new HttpClient
            {
                Request = { Accept = HttpContentTypes.ApplicationXml }
            };

            dynamic emptyPost = new ExpandoObject();            
            EasyHttp.Http.HttpResponse response;
            try
            {
                response = http.Post(url, emptyPost, HttpContentTypes.ApplicationXml);
            }
            catch (WebException ex)
            {
                _log.ErrorFormat("Error: WebException - {0}", ex.Message);
                return false;
            }

            if (response.StatusCode != HttpStatusCode.OK)
            {
                _log.InfoFormat("Response = {0} - {1}", response.StatusCode, response.StatusDescription);
                _log.Info(response.RawText);
                return false;
            }

            XDocument xdoc;
            try
            {
                xdoc = XDocument.Parse(response.RawText);
            }
            catch (XmlException ex)
            {
                _log.ErrorFormat("Error: XmlException parsing API response - {0}", ex.Message);
                _log.Info(response.RawText);
                return false;
            }

            string msg;
            try
            {
                msg = xdoc.Descendants("result").First().Element("message").Value;
            }
            catch (Exception ex)
            {
                _log.ErrorFormat("Error: Exception reading from API response - {0}", ex.Message);
                _log.Info(response.RawText);
                return false;
            }
            if (msg != "Record(s) added successfully")
            {
                _log.InfoFormat("Unexpected XML result: {0}", msg);
                _log.Info(response.RawText);
                return false;
            }

            return true;
        }
    }

(See also this Gist.)

I’m also using log4net here.  I’m a really big fan of log4net, and I use it in almost all of my projects. I have a pretty standard log.config file I use that sets up a RollingFileAppender, with ten files of 100k each. That’s usually enough to keep a few days or weeks worth of history, depending on the level of logging and the level of activity. And I never have to worry about the log files growing out of control; they just keep rolling over. I think log4net is pretty popular, based on the numbers on their NuGet page.

I try to do a lot of error-handling whenever I’m dealing with a REST API. There are plenty of things that can go wrong. You can see in the code above that I try to trap anything that might throw an exception and log it. I’m never sure if I’m doing this the “right” way. I know some people, when writing a routine like this, would just let the exceptions happen, then have a try/catch around the call to the CreateLead method, and deal with it at a higher level.

I haven’t posted much code to my blog lately, so I thought I’d pass along some general-purpose C# code that I recently used in a project. I’m working on a system right now where the original author made some, shall we say, interesting decisions about how to store data in SQL. Specifically, he used varchar fields for most of the numeric data. And, in those fields, he sometimes stores the data in decimal format (e.g. “1.5”), sometimes as fractions (e.g. “1 1/2”) and sometimes as explicitly-signed fractions (“+1 1/2”).  I, of course, need to do LOTS of math on these numbers. The decimal fields can be dealt with using good old TryParse and ToString of course, but there’s no obvious parse routine for fractions, nor is there an obvious way to turn a decimal number back into a fraction string.

The internet, of course, provides. Here is a VB.NET function to turn a fraction string into a decimal and there is some C# code to convert a decimal into a fraction string in this thread. I converted the VB.NET to C#, and cleaned both of them up and put them in a utility class.  Here it is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Globalization;

namespace MySuit.MySuitV2.BLL
{
    public class Utility
    {
        public static decimal FractionToDecimal(string frac)
        {
            // this method should convert a fraction, e.g. "12 1/4" to a decimal, e.g. 12.25.
            // based on http://amrelgarhytech.blogspot.com/2008/03/fraction-to-decimal.html
            // TODO: not sure how best to handle exceptions here. (parse errors, div by zero, null/empty string input...)
            decimal rv;
            int numerator, denominator, wholePart = 0;
            int sign = 1;

            if (string.IsNullOrEmpty(frac))
                return 0m;

            // deal with signs
            frac = frac.Trim().TrimStart('+');
            if (frac[0] == '-')
            {
                frac = frac.TrimStart('-');
                sign = -1;
            }
            frac = frac.Trim();

            if (frac.IndexOf("/") > 0)
            {
                if (frac.IndexOf(" ") > 0)
                {
                    wholePart = int.Parse(frac.Substring(0, frac.IndexOf(" ")));
                    frac = frac.Substring(frac.IndexOf(" "));
                }
                numerator = int.Parse(frac.Substring(0, frac.IndexOf("/")));
                denominator = int.Parse(frac.Substring(frac.IndexOf("/") + 1));
                rv = sign * (wholePart + ((decimal)numerator / denominator));
            }
            else
            {
                rv = decimal.Parse(frac);
            }
            return rv;
        }

        public static string DecimalToFractionSigned(decimal value)
        {
            // always put a sign (+/-) in front
            string rv = DecimalToFraction(value);
            if (rv[0] != '-')
                rv = string.Format("+{0}", rv);
            return rv;
        }

        public static string DecimalToFraction(decimal value)
        {
            // taken from here: http://bit.ly/tHaKrK and modified to work with negative numbers too.

            int sign = 1;
            if (value < 0)
            {
                value = Math.Abs(value);
                sign = -1;
            }

            // get the whole value of the fraction
            decimal mWhole = Math.Truncate(value);

            // get the fractional value
            decimal mFraction = value - mWhole;

            // initialize a numerator and denominator
            uint mNumerator = 0;
            uint mDenominator = 1;

            // ensure that there is actually a fraction
            if (mFraction > 0m)
            {
                // convert the value to a string so that you can count the number of decimal places there are
                string strFraction = mFraction.ToString().Remove(0, 2);

                // store the number of decimal places
                uint intFractLength = (uint)strFraction.Length;

                // set the numerator to have the proper amount of zeros
                mNumerator = (uint)Math.Pow(10, intFractLength);

                // parse the fraction value to an integer that equals [fraction value] * 10^[number of decimal places]
                uint.TryParse(strFraction, out mDenominator);

                // get the greatest common divisor for both numbers
                uint gcd = GreatestCommonDivisor(mDenominator, mNumerator);

                // divide the numerator and the denominator by the greatest common divisor
                mNumerator = mNumerator / gcd;
                mDenominator = mDenominator / gcd;
            }

            // create a string builder
            StringBuilder mBuilder = new StringBuilder();

            // add the whole number if it's greater than 0
            if (mWhole > 0m)
            {
                mBuilder.Append(mWhole);
            }

            // add the fraction if it's greater than 0m
            if (mFraction > 0m)
            {
                if (mBuilder.Length > 0)
                {
                    mBuilder.Append(" ");
                }

                mBuilder.Append(mDenominator);
                mBuilder.Append("/");
                mBuilder.Append(mNumerator);
            }

            if (sign == -1)
                mBuilder.Insert(0, '-');

            return mBuilder.ToString();
        }


        private static uint GreatestCommonDivisor(uint valA, uint valB)
        {
            // return 0 if both values are 0 (no GSD)
            if (valA == 0 && valB == 0)
            {
                return 0;
            }
            // return value b if only a == 0
            else if (valA == 0 && valB != 0)
            {
                return valB;
            }
            // return value a if only b == 0
            else if (valA != 0 && valB == 0)
            {
                return valA;
            }
            // actually find the GSD
            else
            {
                uint first = valA;
                uint second = valB;

                while (first != second)
                {
                    if (first > second)
                    {
                        first = first - second;
                    }
                    else
                    {
                        second = second - first;
                    }
                }

                return first;
            }
        }

    }
}

(This is also in a Gist.)
I hope this helps anyone who might be looking for something similar. Also, I want to reiterate that I didn’t write this code from scratch. I took two existing functions, one in VB and one in C#, converted the VB to C#, cleaned them both up a bit, and put them together.

Luckily, by the way, all of the fractions I’m dealing with resolve to simple decimal numbers; everything is x/2, x/4, or x/8. I don’t have to deal with converting 1/3 to decimal and back. If you need to do that, you probably want a class that stores the fractions as numerator and denominator, and does math on them, as fractions.  There are a couple of those out there, if you look around.