Add button for bumping serial

mdb/admin.py

@@ -6,7 +6,7 @@ from django.db import models
 from django.db.models import Count
 from django.forms import NumberInput
 
-from mdb.forms import InterfaceForm
+from mdb.forms import InterfaceForm, SerialNumberInput
 from mdb.models import (
     DhcpConfig,
     DhcpCustomField,
@@ -32,6 +32,16 @@ from mdb.models import (
 admin.site.site_header = settings.ADMIN_SITE_NAME
 
 
+class SerialFieldAdminMixin:
+    """Render the ``domain_serial`` field with the wide serial widget + button."""
+
+    def formfield_for_dbfield(self, db_field, request, **kwargs):
+        formfield = super().formfield_for_dbfield(db_field, request, **kwargs)
+        if db_field.name == "domain_serial":
+            formfield.widget = SerialNumberInput()
+        return formfield
+
+
 class Ip6AddressInline(admin.TabularInline):
     model = Ip6Address
     extra = 0
@@ -169,7 +179,7 @@ class DhcpCustomFieldInline(admin.TabularInline):
     extra = 0
 
 
-class Ip4SubnetAdmin(admin.ModelAdmin):
+class Ip4SubnetAdmin(SerialFieldAdminMixin, admin.ModelAdmin):
     list_display = [
         "name",
         "network",
@@ -209,7 +219,7 @@ class Ip4SubnetAdmin(admin.ModelAdmin):
         return super(Ip4SubnetAdmin, self).get_queryset(request)
 
 
-class Ip6SubnetAdmin(admin.ModelAdmin):
+class Ip6SubnetAdmin(SerialFieldAdminMixin, admin.ModelAdmin):
     list_display = [
         "name",
         "network",
@@ -266,7 +276,7 @@ class DomainAAAARecordInline(admin.TabularInline):
     extra = 0
 
 
-class DomainAdmin(admin.ModelAdmin):
+class DomainAdmin(SerialFieldAdminMixin, admin.ModelAdmin):
     inlines = [
         DomainSrvRecordInline,
         DomainTxtRecordInline,

mdb/forms.py

@@ -1,10 +1,55 @@
 from django import forms
 from django.core.exceptions import ValidationError
-from django.forms import ModelChoiceField
+from django.forms import ModelChoiceField, NumberInput
+from django.utils.safestring import mark_safe
 
 from mdb.models import Interface, Ip4Address
 
 
+class SerialNumberInput(NumberInput):
+    """Number input for DNS SOA serials (YYYYMMDDXX).
+
+    Renders wide enough to show the full 10-digit serial and adds a button
+    that prefills the field with today's date plus the next available XX
+    counter (incrementing if the field already holds today's serial).
+    """
+
+    def __init__(self, attrs=None):
+        default_attrs = {"style": "width: 12em"}
+        if attrs:
+            default_attrs.update(attrs)
+        super().__init__(default_attrs)
+
+    def render(self, name, value, attrs=None, renderer=None):
+        field = super().render(name, value, attrs, renderer)
+        field_id = (attrs or {}).get("id", "id_%s" % name)
+        extra = """
+<button type="button" class="button" style="margin-left: 0.5em;"
+        onclick="mdbBumpSerial('__ID__')">Today + next serial</button>
+<script>
+if (typeof window.mdbBumpSerial === 'undefined') {
+    window.mdbBumpSerial = function (inputId) {
+        var input = document.getElementById(inputId);
+        if (!input) { return; }
+        var now = new Date();
+        var today = '' + now.getFullYear()
+            + String(now.getMonth() + 1).padStart(2, '0')
+            + String(now.getDate()).padStart(2, '0');
+        var current = (input.value || '').trim();
+        var xx = 1;
+        if (current.length === 10 && current.slice(0, 8) === today) {
+            xx = Math.min(parseInt(current.slice(8), 10) + 1, 99);
+        }
+        input.value = today + String(xx).padStart(2, '0');
+    };
+}
+</script>
+""".replace(
+            "__ID__", field_id
+        )
+        return mark_safe(field + extra)
+
+
 class Ip4ModelChoiceField(ModelChoiceField):
     def label_from_instance(self, obj):
         if not hasattr(obj, "interface"):