Added room Id field for better relationship between objects.

client/lib/fileUpload.coffee

@@ -62,6 +62,7 @@ readAsArrayBuffer = (file, callback) ->
 						name: file.name or file.file.name
 						size: file.file.size
 						type: file.file.type
+						rid: roomId
 
 					upload = new UploadFS.Uploader
 						store: Meteor.fileStore

server/startup/migrations/v20.coffee

@@ -0,0 +1,27 @@
+Meteor.startup ->
+  Migrations.add
+    version: 20
+    up: ->
+      ###
+      # Migrate existing `rocketchat_uploads` documents to include the room Id
+      # where the file was uploaded to. The room Id is retrieved from the message
+      # document created after the file upload.
+      ###
+
+      # list of channel messages which were created after uploading a file
+      msgQuery =
+        rid: { $exists: true }
+        'file._id': { $exists: true }
+      msgOptions =
+        fields:
+          _id: 1
+          rid: 1
+          'file._id': 1
+      cursorFileMessages = RocketChat.models.Messages.find(msgQuery, msgOptions);
+      return unless cursorFileMessages.count()
+
+      _.each( cursorFileMessages.fetch(), (msg) ->
+        fileCollection.update({ _id: msg?.file?._id }, { $set: { rid: msg.rid } }, { $multi: true })
+      )
+
+      console.log 'Updated rocketchat_uploads documents to include the room Id in which they were sent.'