Fixes issue #5 problems with DateTime format for Mixpanel

Mixpanel.NET.nuspec

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>Mixpanel.NET</id>
-    <version>0.2.0</version>
+    <version>0.2.1</version>
     <title>Mixpanel API integration for .NET</title>
     <authors>Chris Nicola</authors>
     <owners>Chris Nicola</owners>

src/Mixpanel.NET/Engage/MixpanelEngage.cs

@@ -28,9 +28,9 @@ private bool Engage(string distinctId, IDictionary<string, object> setProperties
       var dictionary = 
         new Dictionary<string, object> {{"$token", token}, {"$distinct_id", distinctId}};
 
-      if (setProperties != null) dictionary.Add("$set", setProperties);
+      if (setProperties != null) dictionary.Add("$set", setProperties.FormatProperties());
 
-      if (incrementProperties != null) dictionary.Add("$add", incrementProperties);
+      if (incrementProperties != null) dictionary.Add("$add", incrementProperties.FormatProperties());
 
       var data = new JavaScriptSerializer().Serialize(dictionary);
 

src/Mixpanel.NET/Events/MixpanelTracker.cs

@@ -27,26 +27,18 @@ public MixpanelTracker(string token, IMixpanelHttp http = null, TrackerOptions o
 
         public bool Track(string @event, IDictionary<string, object> properties)
         {
-            var propertyBag = new Dictionary<string, object>(properties);
+            var propertyBag = properties.FormatProperties();
             // Standardize token and time values for Mixpanel
             propertyBag["token"] = token;
-            if (_options.SetEventTime)
-            {
-                propertyBag["time"] =
-                    propertyBag.Where(x => x.Key.ToLower() == "time")
-                    .Select(x => x.Value)
-                    .FirstOrDefault() ?? DateTime.UtcNow;
 
-                propertyBag.Remove("Time");
-            }
+            if (_options.SetEventTime && !properties.Keys.Any(x => x.ToLower() == "time"))
+                propertyBag["time"] = DateTime.UtcNow.FormatDate();
 
-            var data =
-                new JavaScriptSerializer()
-                .Serialize(new Dictionary<string, object>
-                {
-                    { "event", @event },
-                    { "properties", propertyBag }
-                });
+            var data = new JavaScriptSerializer().Serialize(new Dictionary<string, object>
+            {
+                { "event", @event },
+                { "properties", propertyBag }
+            });
 
             var values = "data=" + data.Base64Encode();
 

src/Mixpanel.NET/MixpanelExtension.cs

@@ -48,5 +48,25 @@ public static string ComputeHash(this string value) {
       var hexDigest = hash.Aggregate("", (x,y) => x + y.ToString("X").ToLower());
       return hexDigest;
     }
+
+    /// <summary>
+    /// Converts the time to "sortable" format which MixPanel understands
+    /// https://mixpanel.com/docs/properties-or-segments/property-data-types
+    /// http://msdn.microsoft.com/en-us/library/az4se3k1(v=vs.110).aspx
+    /// </summary>
+    public static string FormatDate(this DateTime value) {
+      return value.ToString("s");
+    }
+
+    public static IDictionary<string, object> FormatProperties(this IDictionary<string, object> values) {
+      var output = new Dictionary<string, object>();
+      foreach (var prop in values) {
+        if (prop.Value is DateTime)
+          output[prop.Key] = ((DateTime)prop.Value).FormatDate();
+        else
+          output[prop.Key] = prop.Value;
+      }
+      return output;
+    }
   }
 }