Make URL a Field instead a property (#63)

This PR adds a new Field to all existing Models.
As its a data migrations the Migration is added.

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#63

epdb/management/commands/localize_urls.py

@@ -0,0 +1,50 @@
+from django.apps import apps
+from django.core.management.base import BaseCommand
+
+from django.db.models import F, Value
+from django.db.models.functions import Replace
+
+
+class Command(BaseCommand):
+
+    def add_arguments(self, parser):
+        parser.add_argument(
+            '--old',
+            type=str,
+            help='Old Host, most likely https://envipath.org/',
+            required=True,
+        )
+        parser.add_argument(
+            '--new',
+            type=str,
+            help='New Host, most likely http://localhost:8000/',
+            required=True,
+        )
+
+    def handle(self, *args, **options):
+        MODELS = [
+            'User',
+            'Group',
+            'Package',
+            'Compound',
+            'CompoundStructure',
+            'Pathway',
+            'Edge',
+            'Node',
+            'Reaction',
+            'SimpleAmbitRule',
+            'SimpleRDKitRule',
+            'ParallelRule',
+            'SequentialRule',
+            'Scenario',
+            'Setting',
+            'MLRelativeReasoning',
+            'EnviFormer',
+            'ApplicabilityDomain',
+        ]
+        for model in MODELS:
+            obj_cls = apps.get_model("epdb", model)
+            print(f"Localizing urls for {model}")
+            obj_cls.objects.update(
+                url=Replace(F('url'), Value(options['old']), Value(options['new']))
+            )