Finalize implementation of DynamoDB Streams

moto/dynamodb2/models.py

@@ -1,10 +1,11 @@
 from __future__ import unicode_literals
-from collections import defaultdict
+from collections import defaultdict, namedtuple
 import copy
 import datetime
 import decimal
 import json
 import re
+import uuid
 
 import boto3
 from moto.compat import OrderedDict
@@ -292,6 +293,44 @@ class Item(BaseModel):
                         'ADD not supported for %s' % ', '.join(update_action['Value'].keys()))
 
 
+class StreamRecord(BaseModel):
+    def __init__(self, table, stream_type, event_name, old, new, seq):
+        old_a = old.to_json()['Attributes'] if old is not None else {}
+        new_a = new.to_json()['Attributes'] if new is not None else {}
+
+        rec = old if old is not None else new
+        keys = {table.hash_key_attr: rec.hash_key.to_json()}
+        if table.range_key_attr is not None:
+            keys[table.range_key_attr] = rec.range_key.to_json()
+                
+        self.record = {
+            'eventID': uuid.uuid4().hex,
+            'eventName': event_name,
+            'eventSource': 'aws:dynamodb',
+            'eventVersion': '1.0',
+            'awsRegion': 'us-east-1',
+            'dynamodb': {
+                'StreamViewType': stream_type,
+                'ApproximateCreationDateTime': datetime.datetime.utcnow().isoformat(),
+                'SequenceNumber': seq,
+                'SizeBytes': 1,
+                'Keys': keys
+            }
+        }
+                    
+        if stream_type in ('NEW_IMAGE', 'NEW_AND_OLD_IMAGES'):
+            self.record['dynamodb']['NewImage'] = new_a
+        if stream_type in ('OLD_IMAGE', 'NEW_AND_OLD_IMAGES'):
+            self.record['dynamodb']['OldImage'] = old_a
+
+        # This is a substantial overestimate but it's the easiest to do now
+        self.record['dynamodb']['SizeBytes'] = len(
+            json.dumps(self.record['dynamodb']))
+
+    def to_json(self):
+        return self.record
+
+
 class StreamShard(BaseModel):
     def __init__(self, table):
         self.table = table
@@ -310,15 +349,22 @@ class StreamShard(BaseModel):
 
     def add(self, old, new):
         t = self.table.stream_specification['StreamViewType']
-        if t == 'KEYS_ONLY':
-            self.items.append(new.key)
-        elif t == 'NEW_IMAGE':
-            self.items.append(new)
-        elif t == 'OLD_IMAGE':
-            self.items.append(old)
-        elif t == 'NEW_AND_OLD_IMAGES':
-            self.items.append((old, new))
-                
+        if old is None:
+            event_name = 'INSERT'
+        elif new is None:
+            event_name = 'DELETE'
+        else:
+            event_name = 'MODIFY'
+        seq = len(self.items) + self.starting_sequence_number
+        self.items.append(
+            StreamRecord(self.table, t, event_name, old, new, seq))
+
+    def get(self, start, quantity):
+        start -= self.starting_sequence_number
+        assert start >= 0
+        end = start + quantity
+        return [i.to_json() for i in self.items[start:end]]
+            
 
 class Table(BaseModel):
 
@@ -428,22 +474,22 @@ class Table(BaseModel):
         else:
             range_value = None
 
+        if expected is None:
+            expected = {}
+            lookup_range_value = range_value
+        else:
+            expected_range_value = expected.get(
+                self.range_key_attr, {}).get("Value")
+            if(expected_range_value is None):
+                lookup_range_value = range_value
+            else:
+                lookup_range_value = DynamoType(expected_range_value)
         current = self.get_item(hash_value, lookup_range_value)
+        
         item = Item(hash_value, self.hash_key_type, range_value,
                     self.range_key_type, item_attrs)
 
         if not overwrite:
-            if expected is None:
-                expected = {}
-                lookup_range_value = range_value
-            else:
-                expected_range_value = expected.get(
-                    self.range_key_attr, {}).get("Value")
-                if(expected_range_value is None):
-                    lookup_range_value = range_value
-                else:
-                    lookup_range_value = DynamoType(expected_range_value)
-
             if current is None:
                 current_attr = {}
             elif hasattr(current, 'attrs'):
@@ -508,9 +554,14 @@ class Table(BaseModel):
     def delete_item(self, hash_key, range_key):
         try:
             if range_key:
-                return self.items[hash_key].pop(range_key)
+                item = self.items[hash_key].pop(range_key)
             else:
-                return self.items.pop(hash_key)
+                item = self.items.pop(hash_key)
+
+            if self.stream_shard is not None:
+                self.stream_shard.add(item, None)
+            
+            return item
         except KeyError:
             return None