From 142edc509b99b0d70e2c0c682445fe07baa6650d Mon Sep 17 00:00:00 2001
From: Oliver Roick <oliver.roick@gmail.com>
Date: Mon, 30 Nov 2015 16:09:25 +0000
Subject: [PATCH] Add RandomIDModel

Add RandomIDModel is an abstract base model that creates a random
alpha-numeric ID for the model instance. All Cadasta models must
inherit from this class.
---
 cadasta/config/settings/default.py |  2 --
 cadasta/core/models.py             | 26 ++++++++++++++++++++++++++
 cadasta/core/tests/__init__.py     |  0
 cadasta/core/tests/test_models.py  | 11 +++++++++++
 cadasta/core/tests/testcases.py    | 30 ++++++++++++++++++++++++++++++
 cadasta/core/util.py               | 19 +++++++++++++++++++
 6 files changed, 86 insertions(+), 2 deletions(-)
 create mode 100644 cadasta/core/models.py
 create mode 100644 cadasta/core/tests/__init__.py
 create mode 100644 cadasta/core/tests/test_models.py
 create mode 100644 cadasta/core/tests/testcases.py
 create mode 100644 cadasta/core/util.py

diff --git a/cadasta/config/settings/default.py b/cadasta/config/settings/default.py
index cb74647b4..9a2d323d0 100644
--- a/cadasta/config/settings/default.py
+++ b/cadasta/config/settings/default.py
@@ -33,8 +33,6 @@
     'django.contrib.sessions',
     'django.contrib.messages',
     'django.contrib.staticfiles',
-
-    'organizations'
 )
 
 MIDDLEWARE_CLASSES = (
diff --git a/cadasta/core/models.py b/cadasta/core/models.py
new file mode 100644
index 000000000..2ca8bb9c6
--- /dev/null
+++ b/cadasta/core/models.py
@@ -0,0 +1,26 @@
+from django.db import models
+
+from .util import random_id, ID_FIELD_LENGTH
+
+
+class RandomIDModel(models.Model):
+    id = models.CharField(primary_key=True, max_length=ID_FIELD_LENGTH)
+
+    class Meta:
+        abstract = True
+
+    def save(self, *args, **kwargs):
+        if not self.id:
+            kwargs['force_insert'] = True
+
+            while True:
+                self.id = random_id()
+
+                if not type(self).objects.filter(pk=self.id).exists():
+                    super(RandomIDModel, self).save(*args, **kwargs)
+                    break
+                else:
+                    continue
+
+        else:
+            super(RandomIDModel, self).save(*args, **kwargs)
diff --git a/cadasta/core/tests/__init__.py b/cadasta/core/tests/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/cadasta/core/tests/test_models.py b/cadasta/core/tests/test_models.py
new file mode 100644
index 000000000..3a527ed4d
--- /dev/null
+++ b/cadasta/core/tests/test_models.py
@@ -0,0 +1,11 @@
+from .testcases import AbstractModelTestCase
+from ..models import RandomIDModel
+
+
+class RandomIDModelTest(AbstractModelTestCase):
+    abstract_model = RandomIDModel
+
+    def test_save(self):
+        instance = self.model()
+        instance.save()
+        self.assertIsNotNone(instance.id)
diff --git a/cadasta/core/tests/testcases.py b/cadasta/core/tests/testcases.py
new file mode 100644
index 000000000..ef16eec23
--- /dev/null
+++ b/cadasta/core/tests/testcases.py
@@ -0,0 +1,30 @@
+from django.test import TestCase
+from django.db import connection
+from django.core.management.color import no_style
+from django.db.models.base import ModelBase
+
+
+class AbstractModelTestCase(TestCase):
+    def setUp(self):
+        # Create a dummy model which extends the abstract model
+        self.model = ModelBase(
+            '__TestModel__' + self.abstract_model.__name__,
+            (self.abstract_model,),
+            {'__module__': self.abstract_model.__module__}
+        )
+
+        # Create the schema for our test model
+        self._style = no_style()
+        sql, _ = connection.creation.sql_create_model(self.model, self._style)
+
+        self._cursor = connection.cursor()
+        for statement in sql:
+            self._cursor.execute(statement)
+
+    def tearDown(self):
+        # Delete the schema for the test model
+        sql = connection.creation.sql_destroy_model(
+            self.model, (), self._style
+        )
+        for statement in sql:
+            self._cursor.execute(statement)
diff --git a/cadasta/core/util.py b/cadasta/core/util.py
new file mode 100644
index 000000000..86020bf22
--- /dev/null
+++ b/cadasta/core/util.py
@@ -0,0 +1,19 @@
+import random
+import string
+
+
+ID_FIELD_LENGTH = 24
+
+alphabet = string.ascii_lowercase + string.digits
+for loser in 'l1o0':
+    i = alphabet.index(loser)
+    alphabet = alphabet[:i] + alphabet[i+1:]
+
+
+def byte_to_base32_chr(byte):
+    return alphabet[byte & 31]
+
+
+def random_id():
+    rand_id = [random.randint(0, 0xFF) for i in range(ID_FIELD_LENGTH)]
+    return ''.join(map(byte_to_base32_chr, rand_id))