diff --git a/db.sqlite3 b/db.sqlite3
index df2e02a..cd19cc0 100644
Binary files a/db.sqlite3 and b/db.sqlite3 differ
diff --git a/markt/__pycache__/admin.cpython-38.pyc b/markt/__pycache__/admin.cpython-38.pyc
index 0df4f36..5e1ab1c 100644
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diff --git a/markt/__pycache__/models.cpython-38.pyc b/markt/__pycache__/models.cpython-38.pyc
index 89787cf..fe50b7b 100644
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diff --git a/markt/admin.py b/markt/admin.py
index dba76c4..ba45202 100644
--- a/markt/admin.py
+++ b/markt/admin.py
@@ -6,6 +6,7 @@ class OrderAdmin(admin.ModelAdmin):
     list_display = ("Order_ID", "Voorraad_ID", "Amount", "Prijs" )
 
 
+
 @admin.register(Factuur)
 class FactuurAdmin(admin.ModelAdmin):
     list_display = ("Factuur_ID", "Klant_ID", "total" )
diff --git a/markt/migrations/0004_auto_20200524_1506.py b/markt/migrations/0004_auto_20200524_1506.py
new file mode 100644
index 0000000..c58ed15
--- /dev/null
+++ b/markt/migrations/0004_auto_20200524_1506.py
@@ -0,0 +1,23 @@
+# Generated by Django 3.0.6 on 2020-05-24 18:06
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('markt', '0003_factuur_orders'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='factuur',
+            name='Subtotal',
+            field=models.FloatField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='factuur',
+            name='total',
+            field=models.FloatField(blank=True, null=True),
+        ),
+    ]
diff --git a/markt/migrations/0005_remove_order_factuur_id.py b/markt/migrations/0005_remove_order_factuur_id.py
new file mode 100644
index 0000000..eb525b5
--- /dev/null
+++ b/markt/migrations/0005_remove_order_factuur_id.py
@@ -0,0 +1,17 @@
+# Generated by Django 3.0.6 on 2020-05-24 18:10
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('markt', '0004_auto_20200524_1506'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='order',
+            name='Factuur_ID',
+        ),
+    ]
diff --git a/markt/migrations/0006_order_factuur_id.py b/markt/migrations/0006_order_factuur_id.py
new file mode 100644
index 0000000..aba70e7
--- /dev/null
+++ b/markt/migrations/0006_order_factuur_id.py
@@ -0,0 +1,20 @@
+# Generated by Django 3.0.6 on 2020-05-24 18:13
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('markt', '0005_remove_order_factuur_id'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='order',
+            name='Factuur_ID',
+            field=models.ForeignKey(default=1, on_delete=django.db.models.deletion.PROTECT, to='markt.Factuur'),
+            preserve_default=False,
+        ),
+    ]
diff --git a/markt/migrations/0007_remove_order_factuur_id.py b/markt/migrations/0007_remove_order_factuur_id.py
new file mode 100644
index 0000000..64d88bf
--- /dev/null
+++ b/markt/migrations/0007_remove_order_factuur_id.py
@@ -0,0 +1,17 @@
+# Generated by Django 3.0.6 on 2020-05-24 18:14
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('markt', '0006_order_factuur_id'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='order',
+            name='Factuur_ID',
+        ),
+    ]
diff --git a/markt/migrations/0008_auto_20200524_1522.py b/markt/migrations/0008_auto_20200524_1522.py
new file mode 100644
index 0000000..392cc0a
--- /dev/null
+++ b/markt/migrations/0008_auto_20200524_1522.py
@@ -0,0 +1,25 @@
+# Generated by Django 3.0.6 on 2020-05-24 18:22
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('markt', '0007_remove_order_factuur_id'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='order',
+            name='Factuur_ID',
+            field=models.ForeignKey(default=1, on_delete=django.db.models.deletion.PROTECT, to='markt.Factuur'),
+            preserve_default=False,
+        ),
+        migrations.AlterField(
+            model_name='factuur',
+            name='Orders',
+            field=models.ManyToManyField(blank=True, null=True, to='markt.Order'),
+        ),
+    ]
diff --git a/markt/migrations/0009_remove_factuur_orders.py b/markt/migrations/0009_remove_factuur_orders.py
new file mode 100644
index 0000000..c7ac524
--- /dev/null
+++ b/markt/migrations/0009_remove_factuur_orders.py
@@ -0,0 +1,17 @@
+# Generated by Django 3.0.6 on 2020-05-24 18:28
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('markt', '0008_auto_20200524_1522'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='factuur',
+            name='Orders',
+        ),
+    ]
diff --git a/markt/migrations/0010_auto_20200524_1530.py b/markt/migrations/0010_auto_20200524_1530.py
new file mode 100644
index 0000000..37dc6eb
--- /dev/null
+++ b/markt/migrations/0010_auto_20200524_1530.py
@@ -0,0 +1,22 @@
+# Generated by Django 3.0.6 on 2020-05-24 18:30
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('markt', '0009_remove_factuur_orders'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='order',
+            name='Factuur_ID',
+        ),
+        migrations.AddField(
+            model_name='factuur',
+            name='Orders',
+            field=models.ManyToManyField(blank=True, null=True, to='markt.Order'),
+        ),
+    ]
diff --git a/markt/migrations/__pycache__/0004_auto_20200524_1506.cpython-38.pyc b/markt/migrations/__pycache__/0004_auto_20200524_1506.cpython-38.pyc
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index 0000000..7c73846
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index 0000000..e03cd16
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diff --git a/markt/migrations/__pycache__/0009_remove_factuur_orders.cpython-38.pyc b/markt/migrations/__pycache__/0009_remove_factuur_orders.cpython-38.pyc
index 306b726..d714d54 100644
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diff --git a/markt/migrations/__pycache__/0010_auto_20200524_1530.cpython-38.pyc b/markt/migrations/__pycache__/0010_auto_20200524_1530.cpython-38.pyc
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diff --git a/markt/models.py b/markt/models.py
index 4f23799..f8086ce 100644
--- a/markt/models.py
+++ b/markt/models.py
@@ -16,6 +16,7 @@ class Houtsoort(models.Model):
     def __str__(self):
         """String for representing the Model object."""
         return self.Houtsoort_naam
+
     class Meta:
         db_table = "Houtsoort"
         verbose_name_plural = "Houtsoorten"
@@ -33,6 +34,7 @@ class Formaat(models.Model):
     def __str__(self):
         """String for representing the Model object."""
         return self.Formaat + " " + str(self.Lengte) + "m"
+
     class Meta:
         db_table = "Formaat"
         verbose_name_plural = "Formaten"
@@ -60,6 +62,7 @@ class Houtmarkt(models.Model):
     def __str__(self):
         """String for representing the Model object."""
         return self.Houtmarkt_naam
+
     class Meta:
         db_table = "Houtmarkt"
         verbose_name_plural = "Houtmarkten"
@@ -79,7 +82,8 @@ class Voorraad(models.Model):
 
     def __str__(self):
         """String for representing the Model object."""
-        return str(self.Format_ID) + " " +  self.Hout_ID.Houtsoort_naam
+        return str(self.Format_ID) + " " + self.Hout_ID.Houtsoort_naam
+
     class Meta:
         db_table = "Voorraad"
         verbose_name_plural = "Voorraad"
@@ -100,17 +104,20 @@ class Klant(models.Model):
     def __str__(self):
         """String for representing the Model object."""
         return self.Klant_naam
+
     class Meta:
         db_table = "Klant"
         verbose_name_plural = "Klanten"
 
+
 class Order(models.Model):
-    Order_ID =  models.AutoField(primary_key=True)
+    Order_ID = models.AutoField(primary_key=True)
     Voorraad_ID = models.ForeignKey("Voorraad", on_delete=models.PROTECT)
-    Factuur_ID = models.ForeignKey("Factuur", on_delete=models.PROTECT)
+    # Factuur_ID = models.ForeignKey("Factuur", on_delete=models.PROTECT)
     Amount = models.IntegerField()
-    
+
     Prijs = models.FloatField(null=True, blank=True)
+
     def get_absolute_url(self):
         """Returns the url to access a particular instance of the model."""
         return reverse('model-detail-view', args=[str(self.Order_ID)])
@@ -118,12 +125,17 @@ class Order(models.Model):
     def __str__(self):
         """String for representing the Model object."""
         return "{} {}".format(self.Amount, self.Voorraad_ID)
+
     class Meta:
         db_table = "Order"
         verbose_name_plural = "Orders"
 
     def save(self, *args, **kwargs):
         self.Prijs = self.Voorraad_ID.Prijs * self.Amount
+        new_amount = self.Voorraad_ID.Voorraad_Amount - self.Amount
+        if new_amount < 0:
+            raise ValueError("Er zijn maar {} in voorraad".format(self.Voorraad_ID.Voorraad_Amount))
+
         self.Voorraad_ID.Voorraad_Amount -= self.Amount
         self.Voorraad_ID.save()
         return super(Order, self).save(*args, **kwargs)
@@ -132,7 +144,7 @@ class Order(models.Model):
 class Factuur(models.Model):
     Factuur_ID = models.AutoField(primary_key=True)
     Klant_ID = models.ForeignKey("Klant", on_delete=models.PROTECT)
-    Orders = models.ManyToManyField("Order")
+    Orders = models.ManyToManyField("Order", null=True, blank=True)
     Korting_percent = models.FloatField()
     Subtotal = models.FloatField(null=True, blank=True)
     total = models.FloatField(null=True, blank=True)
@@ -144,11 +156,14 @@ class Factuur(models.Model):
     def __str__(self):
         """String for representing the Model object."""
         return str(self.Factuur_ID)
+
     def save(self, *args, **kwargs):
+        super(Factuur, self).save(*args, **kwargs)
         self.Subtotal = sum([i.Prijs for i in self.Orders.all()])
         self.total = self.Subtotal * (1 - self.Korting_percent/100)
 
         return super(Factuur, self).save(*args, **kwargs)
+
     class Meta:
         db_table = "Factuur"
         verbose_name_plural = "Facturen"