Decouple Subject from Tracker (closes snowplow#144)

Author: jbeemster

src/main/java/com/snowplowanalytics/snowplow/tracker/Tracker.java

@@ -129,10 +129,11 @@ public Tracker build() {
     /**
      * Builds and Adds a finalised payload which is ready for sending.
      *
-     * @param payload   The raw event Payload
-     * @param contexts  Custom context for the event
+     * @param payload The raw event Payload
+     * @param contexts Custom context for the event
+     * @param eventSubject An optional event specific Subject
      */
-    private void addTrackerPayload(TrackerPayload payload, List<SelfDescribingJson> contexts) {
+    private void addTrackerPayload(TrackerPayload payload, List<SelfDescribingJson> contexts, Subject eventSubject) {
 
         // Add default parameters to the payload
         payload.add(Parameter.PLATFORM, platform.toString());
@@ -147,8 +148,10 @@ private void addTrackerPayload(TrackerPayload payload, List<SelfDescribingJson>
         }
 
         // Add subject if available
-        if (this.subject != null) {
-            payload.addMap(new HashMap<String, Object>(subject.getSubject()));
+        if (eventSubject != null) {
+            payload.addMap(new HashMap<String, Object>(eventSubject.getSubject()));
+        } else if (this.subject != null) {
+            payload.addMap(new HashMap<String, Object>(this.subject.getSubject()));
         }
 
         // Send the event!
@@ -288,7 +291,8 @@ public DevicePlatform getPlatform() {
     public void track(PageView event) {
         List<SelfDescribingJson> context = event.getContext();
         TrackerPayload payload = event.getPayload();
-        addTrackerPayload(payload, context);
+        Subject subject = event.getSubject();
+        addTrackerPayload(payload, context, subject);
     }
 
     /**
@@ -299,7 +303,8 @@ public void track(PageView event) {
     public void track(Structured event) {
         List<SelfDescribingJson> context = event.getContext();
         TrackerPayload payload = event.getPayload();
-        addTrackerPayload(payload, context);
+        Subject subject = event.getSubject();
+        addTrackerPayload(payload, context, subject);
     }
 
     /**
@@ -312,7 +317,8 @@ public void track(Structured event) {
     public void track(EcommerceTransaction event) {
         List<SelfDescribingJson> context = event.getContext();
         TrackerPayload payload = event.getPayload();
-        addTrackerPayload(payload, context);
+        Subject subject = event.getSubject();
+        addTrackerPayload(payload, context, subject);
 
         // Track each TransactionItem individually
         long timestamp = event.getTimestamp();
@@ -330,7 +336,8 @@ public void track(EcommerceTransaction event) {
     private void track(EcommerceTransactionItem event, long timestamp) {
         List<SelfDescribingJson> context = event.getContext();
         TrackerPayload payload = event.getPayload(timestamp);
-        addTrackerPayload(payload, context);
+        Subject subject = event.getSubject();
+        addTrackerPayload(payload, context, subject);
     }
 
     /**
@@ -341,7 +348,8 @@ private void track(EcommerceTransactionItem event, long timestamp) {
     public void track(Unstructured event) {
         List<SelfDescribingJson> context = event.getContext();
         TrackerPayload payload = event.getPayload(base64Encoded);
-        addTrackerPayload(payload, context);
+        Subject subject = event.getSubject();
+        addTrackerPayload(payload, context, subject);
     }
 
     /**
@@ -355,6 +363,7 @@ public void track(ScreenView event) {
                 .customContext(event.getContext())
                 .timestamp(event.getTimestamp())
                 .eventId(event.getEventId())
+                .subject(event.getSubject())
                 .build());
     }
 
@@ -369,6 +378,7 @@ public void track(TimingWithCategory event) {
                 .customContext(event.getContext())
                 .timestamp(event.getTimestamp())
                 .eventId(event.getEventId())
+                .subject(event.getSubject())
                 .build());
     }
 }

src/main/java/com/snowplowanalytics/snowplow/tracker/events/Event.java

@@ -21,6 +21,7 @@
 import com.google.common.base.Preconditions;
 
 // This library
+import com.snowplowanalytics.snowplow.tracker.Subject;
 import com.snowplowanalytics.snowplow.tracker.Utils;
 import com.snowplowanalytics.snowplow.tracker.constants.Parameter;
 import com.snowplowanalytics.snowplow.tracker.payload.SelfDescribingJson;
@@ -38,12 +39,14 @@ public class Event {
     protected final List<SelfDescribingJson> context;
     protected final long timestamp;
     protected final String eventId;
+    protected final Subject subject;
 
     public static abstract class Builder<T extends Builder<T>> {
 
         private List<SelfDescribingJson> context = new LinkedList<SelfDescribingJson>();
         private long timestamp = System.currentTimeMillis();
         private String eventId = Utils.getEventId();
+        private Subject subject = null;
 
         protected abstract T self();
 
@@ -81,6 +84,17 @@ public T eventId(String eventId) {
             return self();
         }
 
+        /**
+         * A custom subject for the event.
+         *
+         * @param subject the eventId
+         * @return itself
+         */
+        public T subject(Subject subject) {
+            this.subject = subject;
+            return self();
+        }
+
         public Event build() {
             return new Event(this);
         }
@@ -107,6 +121,7 @@ protected Event(Builder<?> builder) {
         this.context = builder.context;
         this.timestamp = builder.timestamp;
         this.eventId = builder.eventId;
+        this.subject = builder.subject;
     }
 
     /**
@@ -130,6 +145,13 @@ public String getEventId() {
         return this.eventId;
     }
 
+    /**
+     * @return the event subject
+     */
+    public Subject getSubject() {
+        return this.subject;
+    }
+
     /**
      * Adds the default parameters to a TrackerPayload object.
      *

src/test/java/com/snowplowanalytics/snowplow/tracker/TrackerTest.java

@@ -345,6 +345,42 @@ public void testTrackTimingWithCategory() {
                 .build(), result);
     }
 
+    @Test
+    public void testTrackTimingWithCategoryWithSubject() {
+        Subject s1 = new Subject();
+        s1.setIpAddress("127.0.0.1");
+        s1.setTimezone("Etc/UTC");
+
+        // When
+        tracker.track(TimingWithCategory.builder()
+                .category("category")
+                .label("label")
+                .variable("variable")
+                .timing(10)
+                .customContext(contexts)
+                .timestamp(123456)
+                .eventId(EXPECTED_EVENT_ID)
+                .subject(s1)
+                .build());
+
+        // Then
+        verify(emitter).emit(captor.capture());
+        Map result = captor.getValue().getMap();
+        assertEquals(ImmutableMap.<String, Object>builder()
+                .put("p", "srv")
+                .put("tv", Version.TRACKER)
+                .put("e", "ue")
+                .put("ip", "127.0.0.1")
+                .put("cx", EXPECTED_BASE64_CONTEXTS)
+                .put("eid", EXPECTED_EVENT_ID)
+                .put("tna", "AF003")
+                .put("tz", "Etc/UTC")
+                .put("ue_px", "eyJzY2hlbWEiOiJpZ2x1OmNvbS5zbm93cGxvd2FuYWx5dGljcy5zbm93cGxvdy91bnN0cnVjdF9ldmVudC9qc29uc2NoZW1hLzEtMC0wIiwiZGF0YSI6eyJzY2hlbWEiOiJpZ2x1OmNvbS5zbm93cGxvd2FuYWx5dGljcy5zbm93cGxvdy90aW1pbmcvanNvbnNjaGVtYS8xLTAtMCIsImRhdGEiOnsiZWlkIjoiMTVlOWIxNDktNjAyOS00ZjZlLTg0NDctNWI5Nzk3YzllNmJlIiwidGltaW5nIjoiMTAiLCJ2YXJpYWJsZSI6InZhcmlhYmxlIiwibGFiZWwiOiJsYWJlbCIsImNhdGVnb3J5IjoiY2F0ZWdvcnkiLCJkdG0iOiIxMjM0NTYifX19")
+                .put("dtm", "123456")
+                .put("aid", "cloudfront")
+                .build(), result);
+    }
+
     @Test
     public void testDefaultPlatform() throws Exception {
         Subject subject = new Subject();