Merge branch 'fix/faster-activemembers-admin' into 'master'

Optimize the activemembers admin

See merge request !609

website/activemembers/admin.py

 from django.contrib import admin
+from django.contrib.auth.models import Permission
+from django.forms import BaseInlineFormSet, ModelForm
 
 from activemembers.forms import CommitteeMembershipForm
 from utils.translation import TranslatedModelAdmin
 from . import models
 
 
+class CommitteeMembershipInlineFormSet(BaseInlineFormSet):
+    """
+    Solely here for performance reasons.
+
+    Needed because the `__str__()` of `CommitteeMembership` (which is displayed
+    above each inline form) uses the username, name of the member and name of
+    the committee.
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.queryset = self.queryset.select_related('member', 'committee')
+
+
 class CommitteeMembershipInline(admin.StackedInline):
     model = models.CommitteeMembership
+    formset = CommitteeMembershipInlineFormSet
     can_delete = False
     ordering = ('since',)
     extra = 0
+    # TODO: replace this with `autocomplete_fields` in Django 2.0
+    raw_id_fields = ('member',)
+
+
+class CommitteeForm(ModelForm):
+    """
+    Solely here for performance reasons.
+
+    Needed because the `__str__()` of `Permission` (which is displayed in the
+    permissions selection box) also prints the corresponding app and
+    `content_type` for each permission.
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.fields['permissions'].queryset = (Permission
+                                               .objects
+                                               .select_related('content_type'))
 
 
 @admin.register(models.Committee)
 class CommitteeAdmin(TranslatedModelAdmin):
     inlines = (CommitteeMembershipInline,)
+    form = CommitteeForm
     list_display = ('name', 'since', 'until', 'active', 'email')
     list_filter = ('until', 'active',)
     search_fields = ('name', 'description')
@@ -39,6 +75,7 @@ class CommitteeAdmin(TranslatedModelAdmin):
 @admin.register(models.Board)
 class BoardAdmin(TranslatedModelAdmin):
     inlines = (CommitteeMembershipInline,)
+    form = CommitteeForm
     exclude = ('is_board',)
     filter_horizontal = ('permissions',)
 
@@ -51,10 +88,11 @@ class CommitteeMembershipAdmin(TranslatedModelAdmin):
     form = CommitteeMembershipForm
     list_display = ('member', 'committee', 'since', 'until', 'chair', 'role')
     list_filter = ('committee',)
+    list_select_related = ('member', 'committee',)
     search_fields = ('member__first_name', 'member__last_name',
                      'member__email')
 
 
 @admin.register(models.Mentorship)
-class MentorsAdmin(admin.ModelAdmin):
-    pass
+class MentorshipAdmin(admin.ModelAdmin):
+    list_select_related = ('member',)