Merge pull request #737 from dynamoosejs/emptyDocumentInitializer

Empty document initializer bug

lib/Document.js

@@ -10,7 +10,7 @@ function DocumentCarrier(model) {
 
 	// Document represents an item in a Model that is either pending (not saved) or saved
 	class Document {
-		constructor(object, settings = {}) {
+		constructor(object = {}, settings = {}) {
 			const documentObject = Document.isDynamoObject(object) ? aws.converter().unmarshall({...object}) : object;
 			Object.keys(documentObject).forEach((key) => this[key] = documentObject[key]);
 			this[internalProperties] = {};

test/Document.js

@@ -922,6 +922,19 @@ describe("Document", () => {
 					}]);
 				});
 
+				it("Should work correctly if attributes added to document after initalization", async () => {
+					putItemFunction = () => Promise.resolve();
+					User = new Model("User", {"id": Number, "name": String}, {"create": false, "waitForActive": false});
+					user = new User();
+					user.id = 1;
+					user.name = "Charlie";
+					await callType.func(user).bind(user)();
+					expect(putParams).to.eql([{
+						"Item": {"id": {"N": "1"}, "name": {"S": "Charlie"}},
+						"TableName": "User"
+					}]);
+				});
+
 				it("Should throw error if object contains properties that have type mismatch with schema", () => {
 					putItemFunction = () => Promise.resolve();
 					User = new Model("User", {"id": Number, "name": String, "age": Number}, {"create": false, "waitForActive": false});