Add INVENTREE_BASE_URL setting

- Also adds callable validator!

InvenTree/common/models.py

@@ -18,7 +18,7 @@ from djmoney.contrib.exchange.models import convert_money
 from djmoney.contrib.exchange.exceptions import MissingRate
 
 from django.utils.translation import ugettext as _
-from django.core.validators import MinValueValidator
+from django.core.validators import MinValueValidator, URLValidator
 from django.core.exceptions import ValidationError
 
 import InvenTree.helpers
@@ -64,6 +64,13 @@ class InvenTreeSetting(models.Model):
             'default': 'My company name',
         },
 
+        'INVENTREE_BASE_URL': {
+            'name': _('Base URL'),
+            'description': _('Base URL for server instance'),
+            'validator': URLValidator(),
+            'default': '',
+        },
+
         'INVENTREE_DEFAULT_CURRENCY': {
             'name': _('Default Currency'),
             'description': _('Default currency'),
@@ -528,6 +535,11 @@ class InvenTreeSetting(models.Model):
             
             return
 
+        if callable(validator):
+            # We can accept function validators with a single argument
+            print("Running validator function")
+            validator(self.value)
+
         # Boolean validator
         if validator == bool:
             # Value must "look like" a boolean value