diff --git a/lib/data/models/invoice_model.dart b/lib/data/models/invoice_model.dart
index 7c6c5c958..db53d069b 100644
--- a/lib/data/models/invoice_model.dart
+++ b/lib/data/models/invoice_model.dart
@@ -260,7 +260,8 @@ abstract class InvoiceItemEntity extends Object with BaseEntity implements Built
   static int counter = 0;
   factory InvoiceItemEntity() {
     return _$InvoiceItemEntity._(
-      id: --InvoiceItemEntity.counter
+      id: --InvoiceItemEntity.counter,
+      qty: 1.0,
     );
   }
 
diff --git a/lib/data/repositories/credit_repository.dart b/lib/data/repositories/credit_repository.dart
index 4a79044ce..e142e9e58 100644
--- a/lib/data/repositories/credit_repository.dart
+++ b/lib/data/repositories/credit_repository.dart
@@ -31,7 +31,7 @@ class CreditsRepository {
     var data = serializers.serializeWith(CreditEntity.serializer, credit);
     var response;
 
-    if (credit.id == null) {
+    if (credit.isNew()) {
       response = await webClient.post(
           auth.url + '/credits', company.token, json.encode(data));
     } else {
diff --git a/lib/data/repositories/expense_repository.dart b/lib/data/repositories/expense_repository.dart
index 6150b1d98..f3ade11dc 100644
--- a/lib/data/repositories/expense_repository.dart
+++ b/lib/data/repositories/expense_repository.dart
@@ -31,7 +31,7 @@ class ExpenseRepository {
     var data = serializers.serializeWith(ExpenseEntity.serializer, expense);
     var response;
 
-    if (expense.id == null) {
+    if (expense.isNew()) {
       response = await webClient.post(
           auth.url + '/expenses', company.token, json.encode(data));
     } else {
diff --git a/lib/data/repositories/invoice_repository.dart b/lib/data/repositories/invoice_repository.dart
index d54037b6c..eeb8681c0 100644
--- a/lib/data/repositories/invoice_repository.dart
+++ b/lib/data/repositories/invoice_repository.dart
@@ -31,7 +31,7 @@ class InvoiceRepository {
     var data = serializers.serializeWith(InvoiceEntity.serializer, invoice);
     var response;
 
-    if (invoice.id == null) {
+    if (invoice.isNew()) {
       response = await webClient.post(
           auth.url + '/invoices', company.token, json.encode(data));
     } else {
diff --git a/lib/data/repositories/payment_repository.dart b/lib/data/repositories/payment_repository.dart
index 49f8dc8ee..53430115c 100644
--- a/lib/data/repositories/payment_repository.dart
+++ b/lib/data/repositories/payment_repository.dart
@@ -31,7 +31,7 @@ class PaymentsRepository {
     var data = serializers.serializeWith(PaymentEntity.serializer, payment);
     var response;
 
-    if (payment.id == null) {
+    if (payment.isNew()) {
       response = await webClient.post(
           auth.url + '/payments', company.token, json.encode(data));
     } else {
diff --git a/lib/data/repositories/project_repository.dart b/lib/data/repositories/project_repository.dart
index e0a62c5a7..8a6022cb3 100644
--- a/lib/data/repositories/project_repository.dart
+++ b/lib/data/repositories/project_repository.dart
@@ -31,7 +31,7 @@ class ProjectsRepository {
     var data = serializers.serializeWith(ProjectEntity.serializer, project);
     var response;
 
-    if (project.id == null) {
+    if (project.isNew()) {
       response = await webClient.post(
           auth.url + '/projects', company.token, json.encode(data));
     } else {
diff --git a/lib/data/repositories/task_repository.dart b/lib/data/repositories/task_repository.dart
index 03f64708d..ae21163c0 100644
--- a/lib/data/repositories/task_repository.dart
+++ b/lib/data/repositories/task_repository.dart
@@ -31,7 +31,7 @@ class TasksRepository {
     var data = serializers.serializeWith(TaskEntity.serializer, task);
     var response;
 
-    if (task.id == null) {
+    if (task.isNew()) {
       response = await webClient.post(
           auth.url + '/tasks', company.token, json.encode(data));
     } else {
diff --git a/lib/data/repositories/vendor_repository.dart b/lib/data/repositories/vendor_repository.dart
index f8ba7f9b7..d7d26c519 100644
--- a/lib/data/repositories/vendor_repository.dart
+++ b/lib/data/repositories/vendor_repository.dart
@@ -31,7 +31,7 @@ class VendorRepository {
     var data = serializers.serializeWith(VendorEntity.serializer, vendor);
     var response;
 
-    if (vendor.id == null) {
+    if (vendor.isNew()) {
       response = await webClient.post(
           auth.url + '/vendors', company.token, json.encode(data));
     } else {