facture: toggle display of periodicite date fields (#326)

eo_gestion/eo_facture/forms.py

@@ -199,11 +199,28 @@ class ClientForm(forms.ModelForm):
 
 
 class ContratForm(forms.ModelForm):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.fields['periodicite_debut'].widget.attrs['data-depends-on'] = 'periodicite'
+        self.fields['periodicite_fin'].widget.attrs['data-depends-on'] = 'periodicite'
+
+    def clean(self):
+        super().clean()
+        if 'periodicite_debut' in self.changed_data and self.instance.factures.filter(
+            numero_d_echeance__isnull=False
+        ):
+            raise ValidationError(
+                'Vous ne pouvez pas changer le début d\'un contrat périodique qui a déjà des factures'
+            )
+
     class Meta:
         fields = '__all__'
         model = models.Contrat
         localized_fields = ("tva", "montant_sous_traite")
 
+    class Media:
+        js = ['facture.js']
+
 
 class PaymentForm(forms.ModelForm):
     class Meta:

eo_gestion/eo_facture/static/facture.js

@@ -0,0 +1,19 @@
+$(function () {
+    console.log('facture.js loading...');
+    $('[data-depends-on]').each(function (i, elt) {
+        const depends_on_name = $(elt).data('depends-on');
+        const $widget = $('[name=' + depends_on_name + ']');
+        const $form_row = $(elt).parents('.form-row');
+        function update_visibility() {
+            const current_value = $widget.val();
+            const state = current_value != '';
+            $form_row.toggle(state);
+            $form_row.find('label').toggleClass('required', state);
+            $(elt).attr('required', state);
+            $(elt).attr('disabled', ! state); // prevent current value from being submitted
+        }
+        update_visibility();
+        $widget.on('change', update_visibility);
+    });
+    console.log('facture.js loaded.');
+})