refactor(backend): removed dynamic imports 🎊

* Removed all dynamic imports to have more standard Django infrastructre and ease future refactoring
* Removed now useless config files
* Returns the list of available endpoints to the frontend directly from the html
* updated documentation accordingly

Fixes #95

backend/backend_app/admin.py

 from django.contrib import admin
-
 from reversion_compare.admin import CompareVersionAdmin
-from backend_app.config.models import get_models
 
-# We need to register testing models, otherwise we won't be able to test properly,
-# Since no migrations would privide those models.
-# So don't put requires_testing=True
-VERSIONED_MODELS = get_models(versioned=True)  # , requires_testing=False)
-CLASSIC_MODELS = get_models(versioned=False)  # , requires_testing=False)
+from backend_app.models.abstract.versionedEssentialModule import (
+    VersionedEssentialModule,
+)
+from backend_app.models.campus import Campus
+from backend_app.models.campusTaggedItem import CampusTaggedItem
+from backend_app.models.city import City
+from backend_app.models.cityTaggedItem import CityTaggedItem
+from backend_app.models.country import Country
+from backend_app.models.countryDri import CountryDri
+from backend_app.models.countryScholarship import CountryScholarship
+from backend_app.models.countryTaggedItem import CountryTaggedItem
+from backend_app.models.currency import Currency
+from backend_app.models.department import Department
+from backend_app.models.for_testing.moderation import ForTestingModeration
+from backend_app.models.for_testing.versioning import ForTestingVersioning
+from backend_app.models.offer import Offer
+from backend_app.models.pendingModeration import PendingModeration
+from backend_app.models.previousDeparture import PreviousDeparture
+from backend_app.models.previousDepartureFeedback import PreviousDepartureFeedback
+from backend_app.models.recommendation import Recommendation
+from backend_app.models.recommendationList import RecommendationList
+from backend_app.models.specialty import Specialty
+from backend_app.models.tag import Tag
+from backend_app.models.university import University
+from backend_app.models.universityDri import UniversityDri
+from backend_app.models.universityInfo import UniversityInfo
+from backend_app.models.universityScholarship import UniversityScholarship
+from backend_app.models.universitySemestersDates import UniversitySemestersDates
+from backend_app.models.universityTaggedItem import UniversityTaggedItem
+from backend_app.models.userData import UserData
+from backend_app.models.version import Version
+
+ALL_MODELS = [
+    Campus,
+    CampusTaggedItem,
+    City,
+    CityTaggedItem,
+    Country,
+    CountryDri,
+    CountryScholarship,
+    CountryTaggedItem,
+    Currency,
+    Department,
+    Offer,
+    PendingModeration,
+    PreviousDeparture,
+    PreviousDepartureFeedback,
+    Recommendation,
+    RecommendationList,
+    Specialty,
+    Tag,
+    University,
+    UniversityDri,
+    UniversityInfo,
+    UniversityScholarship,
+    UniversitySemestersDates,
+    UniversityTaggedItem,
+    UserData,
+    Version,
+]
+
+# We also register testing to models to make sure migrations are created for them
+
+ALL_MODELS += [ForTestingModeration, ForTestingVersioning]
+
+CLASSIC_MODELS = filter(
+    lambda m: not issubclass(m, VersionedEssentialModule), ALL_MODELS
+)
+VERSIONED_MODELS = filter(lambda m: issubclass(m, VersionedEssentialModule), ALL_MODELS)
 
 #######
 # Register the models

backend/backend_app/checks.py

 from collections import Counter
 
+from backend_app.models.abstract.base import BaseModelViewSet
+from backend_app.models.abstract.versionedEssentialModule import (
+    VersionedEssentialModule,
+)
+from backend_app.permissions.utils import Request, FakeUser
 
-def check_viewsets(viewsets):
+
+def check_viewsets(all_viewsets):
     """
-    Check that if 2 serializers are registered for the same model. Then that model
-    has a get_serializer method to point to the serializer to use to deserialize it.
-    There should be only one of serializer being used per model. Otherwise extra
-    configuration is required.
+    This function performs multiple checks on the viewsets to make sure they are well configured.
+
+    First for all types of viewsets.
+        Check 1: all viewsets have an end_point_route attribute
+        Check 2: all viewsets have working permissions classes
+            See: https://rex-dri.gitlab.utc.fr/rex-dri/documentation/#/Application/Backend/models_serializers_viewsets?id=viewsets
 
-    http://localhost:5000/#/Application/Backend/models_serializers_viewsets
+    Then for REST enpoints:
+        Check 3:
+            Check that if 2 serializers are registered for the same model. Then that model
+            has a get_serializer method to point to the serializer to use to deserialize it.
+            There should be only one of serializer being used per model. Otherwise extra
+            configuration is required.
     """
-    # Prevent cyclic imports
-    from backend_app.models.abstract.versionedEssentialModule import (
-        VersionedEssentialModule,
-    )
 
+    # Check 1
+    for v in all_viewsets:
+        if v.end_point_route is None:
+            raise Exception(
+                "You forget to configure the `end_point_route` "
+                "attribute in the viewset {}".format(v)
+            )
+
+    # Check 2
+    fake_request = Request(FakeUser(["DRI"]), "PUT")
+    for v in all_viewsets:
+        try:
+            for p in v().get_permissions():
+                p.has_permission(fake_request, None)
+        except TypeError:
+            raise Exception(
+                "`permission_classes` on viewset {} are misconfigured.\n"
+                "Have a look at the documentation: "
+                "https://rex-dri.gitlab.utc.fr/rex-dri/documentation/#/Application/Backend/models_serializers_viewsets?id=viewsets".format(
+                    v
+                )
+            )
+
+    # Check 3
     serializers = list()
     models = []
-    for viewset in viewsets:
-        serializer = viewset().get_serializer_class()
+    for v in filter(lambda v: issubclass(v, BaseModelViewSet), all_viewsets):
+        serializer = v().get_serializer_class()
         model = serializer.Meta.model
 
         if issubclass(model, VersionedEssentialModule):

backend/backend_app/config/models.py

-import importlib
-from typing import List, Optional, Union
-
-from backend_app.models.abstract.versionedEssentialModule import (
-    VersionedEssentialModule,
-)
-from django.conf import settings
-
-from .utils import load_viewsets_config
-
-
-def get_models(
-    versioned: Optional[bool] = None,
-    requires_testing: Union[None, bool, "smart"] = None,
-) -> List[object]:
-    """
-    Returns the list of models that could be ingered from the `viewsets_config.yml`
-    config file.
-    Some filtering can be applied to some attributes.
-    If the parameter is `None` then no filtering is applied to this attribute.
-    If the parameter is `True` or `False` the object is returned only if it matched.
-
-    There is one exception for the parameter `requires_testing` if it is set to `smart` then
-    the object is returned only if doesn't require testing or if testing is activated.
-    """
-    out = list()
-
-    for obj in load_viewsets_config():
-
-        if requires_testing is not None:
-            if requires_testing == "smart":
-                if obj.requires_testing and not settings.TESTING:
-                    continue
-            else:
-                if requires_testing and not settings.TESTING:
-                    continue
-                if requires_testing and not obj.requires_testing:
-                    continue
-                if not requires_testing and obj.requires_testing:
-                    continue
-
-        module = importlib.import_module(
-            "backend_app.models.{}".format(obj.import_location)
-        )
-
-        Viewset = getattr(module, obj.viewset)
-
-        if not hasattr(Viewset, "serializer_class"):
-            # It is an API viewset, we don't care about it
-            # API viewsets don't correspond to a model.
-            continue
-
-        Model = Viewset.serializer_class.Meta.model
-        if versioned is not None:
-            if versioned and not issubclass(Model, VersionedEssentialModule):
-                continue
-            if not versioned and issubclass(Model, VersionedEssentialModule):
-                continue
-
-        out.append(Model)
-
-    return list(set(out))  # make sure we return each models at most once

backend/backend_app/config/models_config.yml

-# THIS FILE IS DYNAMICALLY USED FOR THE BACKEND
-# TAKE CARE WHEN MODYFING IT ;)
-
-#################################################
-#  It contains information regarding ow models
-#  are configured.
-#  A restart of the backend server is required
-#  for it to take effect.
-#################################################
-
-# Look at the documentation about config files to know more about this
-# http://localhost:5000/#/Application/Backend/config_files?id=models_configyml
-# https://rex-dri.gitlab.utc.fr/rex-dri/documentation/#/Application/Backend/config_files?id=models_configyml
-
-UserData:
-  moderation_level: 0
-
-Recommendation:
-  moderation_level: 0
-
-RecommendationList:
-  moderation_level: 0
-
-ForTestingModeration:
-  moderation_level: 1
-
-ForTestingVersioning:
-  moderation_level: 1

backend/backend_app/config/utils.py

-from os.path import dirname, join, realpath
-from typing import List
-
-import yaml
-from dotmap import DotMap
-
-CURRENT_DIR = dirname(realpath(__file__))
-
-
-def get_yml_file(name):
-    """
-    Helper function to load config files.
-    """
-    with open(join(CURRENT_DIR, name), "r") as f:
-        return yaml.load(f)
-
-
-def load_viewsets_config() -> List[DotMap]:
-    """
-    Returns the list of api objects without filtering add default attributes
-    added to all objects if they are missing.
-    """
-
-    tmp = get_yml_file("viewsets_config.yml")
-    api_config = []
-    for viewset in tmp.keys():
-        obj = tmp[viewset]
-        obj["viewset"] = viewset
-        api_config.append(obj)
-
-    # clean api_config (add default arguments)
-    DEFAULT_SETTINGS = {
-        "is_api_view": False,
-        "requires_testing": False,
-        "viewset_permission": "default",
-        "api_attr": None,
-        "api_name": None,
-    }
-
-    for obj in api_config:
-        for key in DEFAULT_SETTINGS:
-            if key not in obj:
-                obj[key] = DEFAULT_SETTINGS[key]
-
-    return [DotMap(obj) for obj in api_config]
-
-
-def load_models_config() -> DotMap:
-    """
-    Load the `models_config.yml` config file and returns it as
-    a `DotMap`/dict. No transformation whatsoever is applied.
-    """
-
-    data = get_yml_file("models_config.yml")
-    return DotMap(data)
-
-
-def load_defaults() -> DotMap:
-    """
-    Load the `defaults.yml` config file and returns it as
-    a `DotMap`/dict. No transformation whatsoever is applied.
-    """
-
-    data = get_yml_file("defaults.yml")
-    return DotMap(data)

backend/backend_app/config/viewsets.py

-import importlib
-from typing import List, Optional, Union
-
-from django.conf import settings
-
-from dotmap import DotMap
-
-from .utils import load_viewsets_config
-
-
-def get_viewsets_info(
-    ignore_in_admin: Optional[bool] = None,
-    requires_testing: Union[None, bool, "smart"] = None,
-    is_api_view: Optional[bool] = False,
-) -> List[DotMap]:
-    """
-    Returns a list of DotMap objects corresponding the api config file
-    with filtering applied to some attributes.
-    If the parameter is `None` then no filtering is applied to this attribute.
-    If the parameter is `True` or `False` the object is returned only if it matches.
-
-    There is one exception for the parameter `requires_testing` if it is set to `smart` then
-    the object is returned only if doesn't require testing or if testing is activated.
-    """
-    out = list()
-
-    for obj in load_viewsets_config():
-
-        if ignore_in_admin is not None:
-            if ignore_in_admin and not obj.ignore_in_admin:
-                continue
-            if not ignore_in_admin and obj.ignore_in_admin:
-                continue
-
-        if requires_testing is not None:
-            if requires_testing == "smart":
-                if obj.requires_testing and not settings.TESTING:
-                    continue
-            else:
-                if requires_testing and not settings.TESTING:
-                    continue
-                if requires_testing and not obj.requires_testing:
-                    continue
-                if not requires_testing and obj.requires_testing:
-                    continue
-
-        if is_api_view is not None:
-            if is_api_view and not obj.is_api_view:
-                continue
-            if not is_api_view and obj.is_api_view:
-                continue
-
-        module = importlib.import_module(
-            "backend_app.models.{}".format(obj.import_location)
-        )
-
-        Viewset = getattr(module, obj.viewset)
-        obj.Viewset = Viewset
-
-        out.append(obj)
-
-    return out

backend/backend_app/config/viewsets_config.yml

-# THIS FILE IS DYNAMICALLY USED FOR THE BACKEND AND THE FRONTEND
-# TAKE CARE WHEN MODYFING IT ;)
-
-#################################################
-#  It contains information regarding
-#  how viewsets are configured.
-#  A restart of the backend server and a full
-#  recompile of the frontend is required
-#  for changes it to take effect.
-#################################################
-
-
-# Look at the documentation about config files to know more about this
-# http://localhost:5000/#/Application/Backend/config_files?id=viewsets_configyml
-# https://rex-dri.gitlab.utc.fr/rex-dri/documentation/#/Application/Backend/config_files?id=viewsets_configyml
-
-
-#####################################################
-## Custom Viewsets that doesn't have a model behind
-#####################################################
-AppModerationStatusViewSet:
-  api_end_point: serverModerationStatus
-  import_location: other_viewsets
-  viewset_permission: ReadOnly
-  is_api_view: true
-
-#####################
-## Standard Viewsets
-#####################
-
-CountryViewSet:
-  import_location: country
-  api_end_point: countries
-  viewset_permission: IsStaff | ReadOnly
-
-CityViewSet:
-  import_location: city
-  api_end_point: cities
-  viewset_permission: IsStaff | NoPost
-
-UniversityViewSet:
-  import_location: university
-  api_end_point: universities
-  viewset_permission: IsStaff | NoPost
-
-CampusViewSet:
-  import_location: campus
-  api_end_point: campuses
-
-
-UserDataViewSet:
-  import_location: userData
-  api_end_point: userData
-  api_name: user-data-detail
-  viewset_permission: IsOwner
-
-
-TagViewSet:
-  import_location: tag
-  api_end_point: tags
-  viewset_permission: IsStaff | ReadOnly
-
-CurrencyViewSet:
-  import_location: currency
-  api_end_point: currencies
-  viewset_permission: IsStaff | ReadOnly
-
-DepartmentViewSet:
-  import_location: department
-  api_end_point: departments
-  viewset_permission: IsStaff | ReadOnly
-
-SpecialtyViewSet:
-  import_location: specialty
-  api_end_point: specialties
-  viewset_permission: IsStaff | ReadOnly
-
-OfferViewSet:
-  import_location: offer
-  api_end_point: offers
-  viewset_permission: IsStaff | ReadOnly
-
-
-CountryTaggedItemViewSet:
-  import_location: countryTaggedItem
-  api_end_point: countryTaggedItems
-  api_attr: (?P<country_id>[a-zA-Z]+)
-
-CountryScholarshipViewSet:
-  import_location: countryScholarship
-  api_end_point: countryScholarships
-  api_attr: (?P<country_id>[a-zA-Z]+)
-
-CountryDriViewSet:
-  import_location: countryDri
-  api_end_point: countryDri
-  api_attr: (?P<country_id>[a-zA-Z]+)
-  viewset_permission: IsStaff | IsDri | NoPost
-
-
-
-CityTaggedItemViewSet:
-  import_location: cityTaggedItem
-  api_end_point: cityTaggedItems
-  api_attr: (?P<city_id>[0-9]+)
-
-
-
-UniversityTaggedItemViewSet:
-  import_location: universityTaggedItem
-  api_end_point: universityTaggedItems
-  api_attr: (?P<univ_id>[0-9]+)
-
-UniversityScholarshipViewSet:
-  import_location: universityScholarship
-  api_end_point: universityScholarships
-  api_attr: (?P<univ_id>[0-9]+)
-
-UniversityInfoViewSet:
-  import_location: universityInfo
-  viewset_permission: IsStaff | NoPost
-  api_end_point: universitiesInfo
-
-UniversitySemestersDatesViewSet:
-  import_location: universitySemestersDates
-  api_end_point: universitiesSemestersDates
-  viewset_permission: IsStaff | NoPost
-
-UniversityDriViewSet:
-  import_location: universityDri
-  api_end_point: universityDri
-  api_attr: (?P<univ_id>[0-9]+)
-  viewset_permission: IsStaff | IsDri | NoPost
-
-
-
-CampusTaggedItemViewSet:
-  import_location: campusTaggedItem
-  api_end_point: campusTaggedItems
-  api_attr: (?P<campus_id>[0-9]+)
-
-MainCampusViewSet:
-  import_location: campus
-  api_end_point: mainCampuses
-  viewset_permission: ReadOnly
-
-
-
-RecommendationViewSet:
-  import_location: recommendation
-  api_end_point: userRecommendations
-
-RecommendationListViewSet:
-  import_location: recommendationList
-  api_end_point: userRecommendationLists
-
-PreviousDepartureViewSet:
-  import_location: previousDeparture
-  api_end_point: universitiesPreviousDepartures
-  viewset_permission: ReadOnly
-
-PreviousDepartureFeedbackViewSet:
-  import_location: previousDepartureFeedback
-  api_end_point: universitiesPreviousDepartureFeedback
-
-
-
-PendingModerationViewSet:
-  import_location: pendingModeration
-  api_end_point: pendingModeration
-  viewset_permission: IsStaff
-
-
-VersionViewSet:
-  import_location: version
-  api_end_point: versions
-  api_attr: (?P<content_type_id>[0-9]+)/(?P<object_pk>[0-9A-Za-z]+)
-  api_name: versionsList
-  viewset_permission: IsStaff | ReadOnly
-
-PendingModerationObjViewSet:
-  import_location: pendingModeration
-  api_end_point: pendingModerationObj
-  api_attr: (?P<content_type_id>[0-9]+)/(?P<object_pk>[0-9A-Za-z]+)
-  api_name: pendingModerationObj
-  viewset_permission: ReadOnly
-
-ForTestingModerationViewSet:
-  import_location: for_testing.moderation
-  api_end_point: test/moderation
-  requires_testing: true
-
-ForTestingVersioningViewSet:
-  import_location: for_testing.versioning
-  api_end_point: test/versioning
-  requires_testing: true

backend/backend_app/models/abstract/base.py

+from django.conf import settings
 from django.db import models
+from rest_framework import serializers, viewsets
 
 from backend_app.custom.mySerializerWithJSON import MySerializerWithJSON
-from backend_app.permissions.viewsets import get_viewset_permissions
-from rest_framework import serializers, viewsets
+from backend_app.permissions.default import DEFAULT_VIEWSET_PERMISSIONS
 
 
 class BaseModel(models.Model):
@@ -15,6 +16,11 @@ class BaseModel(models.Model):
     viewset.
     """
 
+    # Look at the documentation about config files to know more about this
+    # https://rex-dri.gitlab.utc.fr/rex-dri/documentation/#/Application/Backend/moderation_and_versioning?id=model-level
+    # http://localhost:5000/#/Application/Backend/moderation_and_versioning?id=model-level
+    moderation_level = settings.DEFAULT_MODEL_MODERATION_LEVEL
+
     class Meta:
         abstract = True
 
@@ -60,17 +66,20 @@ class BaseModelViewSet(viewsets.ModelViewSet):
     """
 
     serializer_class = BaseModelSerializer
+    permission_classes = None
 
-    _permission_classes_cached = None
+    # We store the api endpoint route directly in the viewset classes
+    # so that we can easily access them
+    end_point_route = None
 
-    @property
-    def permission_classes(self):
+    def get_permissions(self):
         """
-        We retrieve permissions classes for the viewsets
-        From the config file and cache it.
+        We override the permission getter to make sure we add the default
+        app viewsets permissions
         """
-        if self._permission_classes_cached is None: