allow european date format input in MaterialPart form

jdav_web/material/admin.py

@@ -1,6 +1,7 @@
 from django.contrib import admin
+from django import forms
 
-from .models import MaterialPart, Ownership
+from .models import MaterialPart, MaterialPartForm, Ownership
 
 
 # Register your models here.
@@ -15,7 +16,8 @@ class OwnershipInline(admin.StackedInline):
 
 class MaterialAdmin(admin.ModelAdmin):
     """Edit view of a MaterialPart"""
-    fields = ['name', 'buy_date', 'lifetime', 'photo']
+
+    form = MaterialPartForm
     list_display = ('name', 'buy_date', 'lifetime', 'not_too_old', 'photo')
     inlines = [OwnershipInline]
 

jdav_web/material/models.py

@@ -2,6 +2,8 @@ from datetime import datetime
 
 from decimal import Decimal
 from django.db import models
+from django.contrib.admin import widgets
+from django import forms
 from django.utils import timezone
 
 # maximum time in years of a material part until being replaced
@@ -34,6 +36,19 @@ class MaterialPart(models.Model):
     not_too_old.boolean = True
     not_too_old.short_description = 'Not too old?'
 
+class MaterialPartForm(forms.ModelForm):
+    """
+    An input form for the `MaterialPart` model.
+
+    This additional class is needed to override djangos default
+    `models.DateField` date format with a european format.
+    """
+    buy_date = forms.DateField(widget=widgets.AdminDateWidget, input_formats=('%d.%m.%Y',))
+
+    class Meta:
+        model = MaterialPart
+        exclude = []
+
 
 class Ownership(models.Model):
     """Represents the connection between a MaterialPart and a Member"""