Allow passing in meta option

This way you can add custom data which will show up in
the event view on metric.io.

lib/metric/track.rb

@@ -8,20 +8,23 @@ class Track
     # @param [String] metric Metric identifier
     # @param [Hash] options Options
     # @option options [Symbol] :amount Amount to track
-    # @option options [Symbol] :trigger Flag for email notification
     # @option options [Symbol] :date Override the default date (today)
+    # @option options [Symbol] :meta Pass in custom meta data about the metric
+    # @option options [Symbol] :trigger Flag for email notification
     # @return [String]
     def self.compose(metric, options = {})
       amount = options[:amount]
       trigger = options[:trigger]
       date = options[:date]
+      meta = options[:meta]
 
       key = "?api_key=" + Metric.configuration.api_key
       url = Metric.configuration.metric_host + '/track'
       url << key
-      url << parse_metric(metric)
+      url << "&metric=#{escape(metric)}"
       url << "&amount=#{amount}" if amount
       url << "&date=#{date}" if date
+      url << "&meta=#{escape(meta)}" if meta
       url << "&trigger=1" if trigger
       url
     end
@@ -39,12 +42,12 @@ def self.track(metric, options = {})
       end
     end
 
-    # CGI escape the metric name so spaces and characters are allowed
+    # CGI escape the input
     #
     # @param [String]
     # @return [String]
-    def self.parse_metric(metric)
-      "&metric=#{CGI.escape(metric)}"
+    def self.escape(input)
+      CGI.escape(input)
     end
 
     private

spec/metric/track_spec.rb

@@ -11,8 +11,8 @@
     Metric::Track.track("hits")
   end
 
-  it "encodes the request url" do
-    Metric::Track.parse_metric("hits and spaces").should == "&metric=hits+and+spaces"
+  it "encodes the input" do
+    Metric::Track.escape("hits and spaces").should == "hits+and+spaces"
   end
 
   it "sends trigger param" do
@@ -26,13 +26,23 @@
   end
 
   it "does nothing if amount is 0" do
-    Metric::Track.track("hits", {:amount => 0}).should == nil
+    Metric::Track.should_not_receive(:compose)
+    Metric::Track.track("hits", {:amount => 0})
   end
 
   it "passes in custom date" do
     url = "https://api.metric.io/track?api_key=spec&metric=hits&date=20120101"
     Metric::Track.compose("hits", {:date => "20120101"}).should == url
   end
-end
 
+  it "passes in meta information" do
+    url = "https://api.metric.io/track?api_key=spec&metric=payment&meta=userid%3A+1"
+    Metric::Track.compose("payment", {:meta => "userid: 1"}).should == url
+  end
+
+  it "sends trigger param" do
+    url = "https://api.metric.io/track?api_key=spec&metric=hits&trigger=1"
+    Metric::Track.compose("hits", {:trigger => true}).should == url
+  end
+end