improve bda inscription form/view code

bda/forms.py

@@ -1,14 +1,42 @@
 # -*- coding: utf-8 -*-
 
-from __future__ import division
-from __future__ import print_function
-from __future__ import unicode_literals
-
 from django import forms
+from django.forms.models import BaseInlineFormSet
 from django.utils import timezone
+
 from bda.models import Attribution, Spectacle
 
 
+class InscriptionInlineFormSet(BaseInlineFormSet):
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        # self.instance is a Participant object
+        tirage = self.instance.tirage
+
+        # set once for all "spectacle" field choices
+        # - restrict choices to the spectacles of this tirage
+        # - force_choices avoid many db requests
+        spectacles = tirage.spectacle_set.select_related('location')
+        choices = [(sp.pk, str(sp)) for sp in spectacles]
+        self.force_choices('spectacle', choices)
+
+    def force_choices(self, name, choices):
+        """Set choices of a field.
+
+        As ModelChoiceIterator (default use to get choices of a
+        ModelChoiceField), it appends an empty selection if requested.
+
+        """
+        for form in self.forms:
+            field = form.fields[name]
+            if field.empty_label is not None:
+                field.choices = [('', field.empty_label)] + choices
+            else:
+                field.choices = choices
+
+
 class TokenForm(forms.Form):
     token = forms.CharField(widget=forms.widgets.Textarea())
 

bda/views.py

@@ -32,6 +32,7 @@ from bda.models import (
 from bda.algorithm import Algorithm
 from bda.forms import (
     TokenForm, ResellForm, AnnulForm, InscriptionReventeForm, SoldForm,
+    InscriptionInlineFormSet,
 )
 
 
@@ -157,60 +158,27 @@ def inscription(request, tirage_id):
         messages.error(request, "Le tirage n'est pas encore ouvert : "
                                 "ouverture le {:s}".format(opening))
         return render(request, 'bda/resume-inscription-tirage.html', {})
+
+    participant, _ = (
+        Participant.objects.select_related('tirage')
+        .get_or_create(user=request.user, tirage=tirage)
+    )
+
     if timezone.now() > tirage.fermeture:
         # Le tirage est fermé.
-        participant, _ = (
-            Participant.objects
-            .get_or_create(user=request.user, tirage=tirage)
-        )
         choices = participant.choixspectacle_set.order_by("priority")
         messages.error(request,
                        " C'est fini : tirage au sort dans la journée !")
         return render(request, "bda/resume-inscription-tirage.html",
                       {"choices": choices})
 
-    def force_for(f, to_choices=None, **kwargs):
-        """Overrides choices for ModelChoiceField.
-
-        Args:
-            f (models.Field): To render as forms.Field
-            to_choices (dict): If a key `f.name` exists, f._choices is set to
-                its value.
-
-        """
-        formfield = f.formfield(**kwargs)
-        if to_choices:
-            if f.name in to_choices:
-                choices = [('', '---------')] + to_choices[f.name]
-                formfield._choices = choices
-        return formfield
-
-    # Restrict spectacles choices to spectacles for this tirage.
-    spectacles = (
-        tirage.spectacle_set
-        .select_related('location')
-    )
-    spectacles_field_choices = [(sp.pk, str(sp)) for sp in spectacles]
-
-    # Allow for spectacle choices to be set once for all.
-    # Form display use 1 request instead of (#forms of formset * #spectacles).
-    # FIXME: Validation still generates too much requests...
-    formfield_callback = partial(
-        force_for,
-        to_choices={
-            'spectacle': spectacles_field_choices,
-        },
-    )
     BdaFormSet = inlineformset_factory(
         Participant,
         ChoixSpectacle,
         fields=("spectacle", "double_choice", "priority"),
-        formfield_callback=formfield_callback,
-    )
-    participant, _ = (
-        Participant.objects
-        .get_or_create(user=request.user, tirage=tirage)
+        formset=InscriptionInlineFormSet,
     )
+
     success = False
     stateerror = False
     if request.method == "POST":