Add PartStart model

- Links parts to users

InvenTree/part/migrations/0016_partstar.py

@@ -0,0 +1,24 @@
+# Generated by Django 2.2 on 2019-05-04 22:45
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('part', '0015_partcategory_default_location'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='PartStar',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('part', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='starred_users', to='part.Part')),
+                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='starred_parts', to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+    ]

InvenTree/part/models.py

@@ -18,6 +18,7 @@ from django.urls import reverse
 from django.db import models
 from django.core.validators import MinValueValidator
 
+from django.contrib.auth.models import User
 from django.db.models.signals import pre_delete
 from django.dispatch import receiver
 
@@ -427,6 +428,18 @@ class PartAttachment(models.Model):
         return os.path.basename(self.attachment.name)
 
 
+class PartStar(models.Model):
+    """ A PartStar object creates a relationship between a User and a Part.
+
+    It is used to designate a Part as 'starred' (or favourited) for a given User,
+    so that the user can track a list of their favourite parts.
+    """
+
+    part = models.ForeignKey(Part, on_delete=models.CASCADE, related_name='starred_users')
+
+    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='starred_parts')
+
+
 class BomItem(models.Model):
     """ A BomItem links a part to its component items.
     A part can have a BOM (bill of materials) which defines