Raise form validation error if site ID/title/server name is unavailable

byceps/blueprints/admin/site/forms.py

@@ -8,13 +8,14 @@
 
 from flask_babel import lazy_gettext, pgettext
 from wtforms import BooleanField, SelectField, StringField
-from wtforms.validators import InputRequired, Length, Optional
+from wtforms.validators import InputRequired, Length, Optional, ValidationError
 
 from byceps.services.board import board_service
 from byceps.services.news import news_channel_service
 from byceps.services.party import party_service
 from byceps.services.shop.shop import shop_service
 from byceps.services.shop.storefront import storefront_service
+from byceps.services.site import site_service
 from byceps.util.forms import MultiCheckboxField
 from byceps.util.l10n import LocalizedForm
 
@@ -79,10 +80,77 @@ class CreateForm(_BaseForm):
         lazy_gettext('ID'), validators=[InputRequired(), Length(min=1, max=40)]
     )
 
+    @staticmethod
+    def validate_id(form, field):
+        site_id = field.data.strip()
+
+        if site_service.find_site(site_id):
+            raise ValidationError(
+                lazy_gettext(
+                    'This value is not available. Please choose another.'
+                )
+            )
+
+    @staticmethod
+    def validate_title(form, field):
+        title = field.data.strip()
+
+        if not site_service.is_title_available(title):
+            raise ValidationError(
+                lazy_gettext(
+                    'This value is not available. Please choose another.'
+                )
+            )
+
+    @staticmethod
+    def validate_server_name(form, field):
+        server_name = field.data.strip()
+
+        if not site_service.is_server_name_available(server_name):
+            raise ValidationError(
+                lazy_gettext(
+                    'This value is not available. Please choose another.'
+                )
+            )
+
 
 class UpdateForm(_BaseForm):
     archived = BooleanField(lazy_gettext('archived'))
 
+    def __init__(
+        self, current_title: str, current_server_name: str, *args, **kwargs
+    ):
+        super().__init__(*args, **kwargs)
+        self._current_title = current_title
+        self._current_server_name = current_server_name
+
+    @staticmethod
+    def validate_title(form, field):
+        title = field.data.strip()
+
+        if title != form._current_title and not site_service.is_title_available(
+            title
+        ):
+            raise ValidationError(
+                lazy_gettext(
+                    'This value is not available. Please choose another.'
+                )
+            )
+
+    @staticmethod
+    def validate_server_name(form, field):
+        server_name = field.data.strip()
+
+        if (
+            server_name != form._current_server_name
+            and not site_service.is_server_name_available(server_name)
+        ):
+            raise ValidationError(
+                lazy_gettext(
+                    'This value is not available. Please choose another.'
+                )
+            )
+
 
 class AssignNewsChannelsForm(LocalizedForm):
     news_channel_ids = MultiCheckboxField(

byceps/blueprints/admin/site/templates/admin/site/create_form.html

@@ -23,8 +23,8 @@ <h1 class="title">{{ page_title }}</h1>
         </div>
       </div>
 
-      {{ form_field(form.id, placeholder='intranet', autofocus='autofocus') }}
-      {{ form_field(form.title, placeholder='Intranet') }}
+      {{ form_field(form.id, placeholder='intranet', caption=_('Has to be unique.'), autofocus='autofocus') }}
+      {{ form_field(form.title, placeholder='Intranet', caption=_('Has to be unique.')) }}
       {{ form_field(form.server_name, placeholder='www.example.com', caption=_('Has to be unique.')) }}
       {{ form_field(form.party_id) }}
       {{ form_field(form.board_id) }}

byceps/blueprints/admin/site/templates/admin/site/update_form.html

@@ -15,7 +15,7 @@ <h1 class="title">{{ page_title }}</h1>
 
   <form action="{{ url_for('.update', site_id=site.id) }}" method="post">
     <div class="box">
-      {{ form_field(form.title, autofocus='autofocus') }}
+      {{ form_field(form.title, caption=_('Has to be unique.'), autofocus='autofocus') }}
       {{ form_field(form.server_name, caption=_('Has to be unique.')) }}
       {{ form_field(form.party_id) }}
       {{ form_field(form.board_id) }}

byceps/blueprints/admin/site/views.py

@@ -232,7 +232,11 @@ def update_form(site_id, erroneous_form=None):
     """Show form to update the site."""
     site = _get_site_or_404(site_id)
 
-    form = erroneous_form if erroneous_form else UpdateForm(obj=site)
+    form = (
+        erroneous_form
+        if erroneous_form
+        else UpdateForm(site.title, site.server_name, obj=site)
+    )
     _fill_in_common_form_choices(form, site.brand_id)
 
     return {
@@ -247,7 +251,7 @@ def update(site_id):
     """Update the site."""
     site = _get_site_or_404(site_id)
 
-    form = UpdateForm(request.form)
+    form = UpdateForm(site.title, site.server_name, request.form)
     _fill_in_common_form_choices(form, site.brand_id)
 
     if not form.validate():

byceps/services/site/site_service.py

@@ -188,6 +188,24 @@ def get_current_sites(
     return {transform(db_site) for db_site in db_sites}
 
 
+def is_title_available(title: str) -> bool:
+    """Check if the title is unused."""
+    return not db.session.scalar(
+        select(db.exists().where(db.func.lower(DbSite.title) == title.lower()))
+    )
+
+
+def is_server_name_available(server_name: str) -> bool:
+    """Check if the server name is unused."""
+    return not db.session.scalar(
+        select(
+            db.exists().where(
+                db.func.lower(DbSite.server_name) == server_name.lower()
+            )
+        )
+    )
+
+
 def _db_entity_to_site(db_site: DbSite) -> Site:
     news_channel_ids = frozenset(
         channel.id for channel in db_site.news_channels