Squashed commit of the following:

commit 0d62e72d72922a84e41c9f2cc21977b794784d1c
Merge: 79fee63 85f2a81
Author: reverend <reverend@reverend2048.de>
Date:   Tue Sep 22 21:55:18 2020 +0200

    Merge branch 'develop' into refactor/models

commit 79fee631d7ac28509067ecdd74078f1a2f6e0be2
Author: reverend <reverend@reverend2048.de>
Date:   Tue Sep 22 21:54:32 2020 +0200

    Updating references for related name

commit 8e07e79df2de2601f2e2eadfdd37eb7c719c51b0
Author: reverend <reverend@reverend2048.de>
Date:   Tue Sep 22 21:53:31 2020 +0200

    Generating of related names fix

commit 5fd804f37a805ae4707e13c3d941bdde3660afea
Merge: 8cc1d3e 3b526c9
Author: reverend <reverend@reverend2048.de>
Date:   Tue Sep 22 21:01:48 2020 +0200

    Merge branch 'develop' into refactor/models

commit 8cc1d3e690211dba6451e86569f00078b23e0621
Author: reverend <reverend@reverend2048.de>
Date:   Tue Sep 22 20:21:08 2020 +0200

    Tests

commit 7c0591e5397f892b1f6fb80725a693c21f90468a
Author: reverend <reverend@reverend2048.de>
Date:   Fri Sep 18 23:53:39 2020 +0200

    Testing PlaceAsset

commit 2e7b49ad1a15173565c81e7eb8bb3f35b9f622a6
Author: reverend <reverend@reverend2048.de>
Date:   Fri Sep 18 22:25:08 2020 +0200

    Restructuring models

commit eb7d03b08b326f9115e70d0fd9ed5d0fc229a362
Author: reverend <reverend@reverend2048.de>
Date:   Fri Sep 18 22:01:54 2020 +0200

    Abstract class Expireable

commit 2b51e741bb5734c5a578beeadef7819fe58b2223
Author: reverend <reverend@reverend2048.de>
Date:   Fri Sep 18 21:54:07 2020 +0200

    Abstract Model for PlaceAsset (i.e. Photoalbums)

django_lostplaces/lostplaces/models/__init__.py

@@ -0,0 +1,4 @@
+from lostplaces.models.abstract_models import *
+from lostplaces.models.place import *
+from lostplaces.models.external_links import *
+from lostplaces.models.models import *

django_lostplaces/lostplaces/models/abstract_models.py

@@ -0,0 +1,61 @@
+
+from django.db import models
+from django.core.validators import MaxValueValidator, MinValueValidator
+
+from taggit.managers import TaggableManager
+
+class Taggable(models.Model):
+    '''
+    This abstract model represtens an object that is taggalble
+    using django-taggit
+    '''
+    class Meta:
+        abstract = True
+        
+    tags = TaggableManager(blank=True)
+    
+class Mapable(models.Model):
+    '''
+    This abstract model class represents an object that can be
+    displayed on a map.
+    '''
+    class Meta:
+        abstract = True
+        
+    name = models.CharField(max_length=50)
+    latitude = models.FloatField(
+        validators=[
+            MinValueValidator(-90),
+            MaxValueValidator(90)
+        ]
+    )
+    longitude = models.FloatField(
+        validators=[
+            MinValueValidator(-180),
+            MaxValueValidator(180)
+        ]
+    )
+
+class Submittable(models.Model):
+    '''
+    This abstract model class represents an object that can be submitted by
+    an explorer.
+    '''
+    class Meta:
+        abstract = True
+
+    submitted_when = models.DateTimeField(auto_now_add=True, null=True)
+    submitted_by = models.ForeignKey(
+        'Explorer',
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name='%(class)ss'
+    )
+
+class Expireable(models.Model):
+    """
+    Base class for things that can expire, i.e. VouchersAv
+    """
+    created_when = models.DateTimeField(auto_now_add=True)
+    expires_when = models.DateTimeField()

django_lostplaces/lostplaces/models/external_links.py

@@ -0,0 +1,14 @@
+from django.db import models
+
+from lostplaces.models.place import PlaceAsset
+
+class ExternalLink(PlaceAsset):
+    
+    class Meta:
+        abstract = True
+
+    url = models.URLField(max_length=200)
+    label = models.CharField(max_length=100)
+
+class PhotoAlbum(ExternalLink):
+    pass

django_lostplaces/lostplaces/models/models.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+'''
+(Data)models which describe the structure of data to be saved into 
+database.
+'''
+
+import uuid
+
+from django.db import models
+from django.contrib.auth.models import User
+from django.db.models.signals import post_save
+from django.dispatch import receiver
+
+from lostplaces.models.abstract_models import Expireable
+
+class Explorer(models.Model):
+    """
+    Profile that is linked to the a User.
+    Every user has a profile.
+    """
+    
+    user = models.OneToOneField(
+        User,
+        on_delete=models.CASCADE,
+        related_name='explorer'
+    )
+
+    def __str__(self):
+        return self.user.username
+        
+@receiver(post_save, sender=User)
+def create_user_profile(sender, instance, created, **kwargs):
+    if created:
+        Explorer.objects.create(user=instance)
+
+@receiver(post_save, sender=User)
+def save_user_profile(sender, instance, **kwargs):
+    instance.explorer.save()
+
+class Voucher(Expireable):
+    """
+    Vouchers are authorization to    created_when = models.DateTimeField(auto_now_add=True)
+    expires_when = models.DateTimeField()kens to allow the registration of new users.
+    A voucher has a code, a creation and a deletion date, which are all 
+    positional. Creation date is being set automatically during voucher 
+    creation. 
+    """
+
+    code = models.CharField(unique=True, max_length=30)
+
+    def __str__(self):
+        return "Voucher " + str(self.code)
+

django_lostplaces/lostplaces/models/place.py

@@ -0,0 +1,129 @@
+import os
+
+from django.db import models
+from django.urls import reverse
+from django.dispatch import receiver
+from django.db.models.signals import post_delete, pre_save
+
+from lostplaces.models.abstract_models import Submittable, Taggable, Mapable
+
+from easy_thumbnails.fields import ThumbnailerImageField
+from easy_thumbnails.files import get_thumbnailer
+
+class Place(Submittable, Taggable, Mapable):
+    """
+    Place defines a lost place (location, name, description etc.).
+    """
+
+    location = models.CharField(max_length=50)
+    description = models.TextField()
+
+    def get_absolute_url(self):
+        return reverse('place_detail', kwargs={'pk': self.pk})
+    
+
+    @classmethod
+    # Get center position of LP-geocoordinates.
+    def average_latlon(cls, place_list):
+        amount = len(place_list)
+        # Init fill values to prevent None
+        longitude = 0
+        latitude = 0
+
+        if amount > 0:
+            for place in place_list:
+                longitude += place.longitude
+                latitude += place.latitude
+            return {'latitude':latitude / amount, 'longitude': longitude / amount}
+
+        return {'latitude': latitude, 'longitude': longitude}
+
+    def __str__(self):
+        return self.name
+
+
+def generate_image_upload_path(instance, filename):
+    """
+    Callback for generating path for uploaded images.
+    Returns filename as: place_pk-placename{-rnd_string}.jpg
+    """
+
+    return 'places/' + str(instance.place.pk) + '-' + str(instance.place.name) + '.' + filename.split('.')[-1]
+
+class PlaceAsset(Submittable):
+    """
+    Assets to a place, i.e. images
+    """
+
+    class Meta:
+            abstract = True
+
+    place = models.ForeignKey(
+        Place,
+        on_delete=models.CASCADE,
+        related_name='%(class)ss',
+        null=True
+    )
+
+class PlaceImage (Submittable):
+    """
+    PlaceImage defines an image file object that points to a file in uploads/.
+    Intermediate image sizes are generated as defined in THUMBNAIL_ALIASES.
+    PlaceImage references a Place to which it belongs.
+    """
+
+    description = models.TextField(blank=True)
+    filename = ThumbnailerImageField(
+        upload_to=generate_image_upload_path, 
+        resize_source=dict(size=(2560, 2560), 
+        sharpen=True)
+    )
+    place = models.ForeignKey(
+        Place,
+        on_delete=models.CASCADE,
+        related_name='placeimages'
+    )
+    
+    def __str__(self):
+        """
+        Returning the name of the corresponding place + id 
+        of this image as textual representation of this instance
+        """
+
+        return 'Image ' + str(self.pk)
+
+
+# These two auto-delete files from filesystem when they are unneeded:
+
+@receiver(post_delete, sender=PlaceImage)
+def auto_delete_file_on_delete(sender, instance, **kwargs):
+    """
+    Deletes file (including thumbnails) from filesystem
+    when corresponding `PlaceImage` object is deleted.
+    """
+    if instance.filename:
+        # Get and delete all files and thumbnails from instance
+        thumbmanager = get_thumbnailer(instance.filename)
+        thumbmanager.delete(save=False)
+
+
+@receiver(pre_save, sender=PlaceImage)
+def auto_delete_file_on_change(sender, instance, **kwargs):
+    """
+    Deletes old file from filesystem
+    when corresponding `PlaceImage` object is updated
+    with new file.
+    """
+    if not instance.pk:
+        return False
+
+    try:
+        old_file = PlaceImage.objects.get(pk=instance.pk).filename
+    except PlaceImage.DoesNotExist:
+        return False
+
+    # No need to delete thumbnails, as they will be overwritten on regeneration.
+    new_file = instance.filename
+    if not old_file == new_file:
+        if os.path.isfile(old_file.path):
+            os.remove(old_file.path)