Preview website title + description in bookmark form

Fix unnecessary selects when rendering bookmarks

.idea/misc.xml

@@ -4,6 +4,9 @@
     <ghcPath>/usr/local/bin/ghc</ghcPath>
     <stackPath>/usr/local/bin/stack</stackPath>
   </component>
+  <component name="JavaScriptSettings">
+    <option name="languageLevel" value="ES6" />
+  </component>
   <component name="ProjectRootManager" version="2" languageLevel="JDK_1_6" project-jdk-name="Python 3.7 (.env)" project-jdk-type="Python SDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>

bookmarks/models.py

@@ -42,8 +42,9 @@ class Bookmark(models.Model):
     tags = models.ManyToManyField(Tag)
 
     # Attributes might be calculated in query
-    tag_count = 0
-    tag_string = ''
+    tag_count = 0  # Projection for number of associated tags
+    tag_string = ''  # Projection for list of tag names, comma-separated
+    tag_projection = False  # Tracks if the above projections were loaded
 
     @property
     def resolved_title(self):
@@ -55,7 +56,8 @@ class Bookmark(models.Model):
 
     @property
     def tag_names(self):
-        if self.tag_string:
+        # If tag projections were loaded then avoid querying all tags (=executing further selects)
+        if self.tag_string or self.tag_projection:
             return parse_tag_string(self.tag_string)
         else:
             return [tag.name for tag in self.tags.all()]

bookmarks/queries.py

@@ -1,5 +1,5 @@
 from django.contrib.auth.models import User
-from django.db.models import Q, Count, Aggregate, CharField
+from django.db.models import Q, Count, Aggregate, CharField, Value, BooleanField
 
 from bookmarks.models import Bookmark, Tag
 
@@ -20,7 +20,8 @@ def query_bookmarks(user: User, query_string: str):
     # Add aggregated tag info to bookmark instances
     query_set = Bookmark.objects \
         .annotate(tag_count=Count('tags'),
-                  tag_string=Concat('tags__name'))
+                  tag_string=Concat('tags__name'),
+                  tag_projection=Value(True, BooleanField()))
 
     # Filter for user
     query_set = query_set.filter(owner=user)
@@ -49,7 +50,7 @@ def query_bookmarks(user: User, query_string: str):
 
 
 def query_tags(user: User, query_string: str):
-    query_set = Tag.objects;
+    query_set = Tag.objects
 
     # Filter for user
     query_set = query_set.filter(owner=user)

bookmarks/services/bookmarks.py

@@ -1,10 +1,9 @@
-import requests
-from bs4 import BeautifulSoup
 from django.contrib.auth.models import User
 from django.utils import timezone
 
 from bookmarks.models import Bookmark, BookmarkForm, parse_tag_string
 from services.tags import get_or_create_tags
+from services.website_loader import load_website_metadata
 
 
 def create_bookmark(form: BookmarkForm, current_user: User):
@@ -34,28 +33,12 @@ def update_bookmark(form: BookmarkForm, current_user: User):
 
 
 def _update_website_metadata(bookmark: Bookmark):
-    # noinspection PyBroadException
-    try:
-        page_text = load_page(bookmark.url)
-        soup = BeautifulSoup(page_text, 'html.parser')
-
-        title = soup.title.string if soup.title is not None else None
-        description_tag = soup.find('meta', attrs={'name': 'description'})
-        description = description_tag['content'] if description_tag is not None else None
-
-        bookmark.website_title = title
-        bookmark.website_description = description
-    except Exception:
-        bookmark.website_title = None
-        bookmark.website_description = None
+    metadata = load_website_metadata(bookmark.url)
+    bookmark.website_title = metadata.title
+    bookmark.website_description = metadata.description
 
 
 def _update_bookmark_tags(bookmark: Bookmark, tag_string: str, user: User):
     tag_names = parse_tag_string(tag_string, ' ')
     tags = get_or_create_tags(tag_names, user)
     bookmark.tags.set(tags)
-
-
-def load_page(url: str):
-    r = requests.get(url)
-    return r.text

bookmarks/services/website_loader.py

@@ -0,0 +1,37 @@
+from dataclasses import dataclass
+
+import requests
+from bs4 import BeautifulSoup
+
+
+@dataclass
+class WebsiteMetadata:
+    url: str
+    title: str
+    description: str
+
+    def to_dict(self):
+        return {
+            'url': self.url,
+            'title': self.title,
+            'description': self.description,
+        }
+
+
+def load_website_metadata(url: str):
+    title = None
+    description = None
+    try:
+        page_text = load_page(url)
+        soup = BeautifulSoup(page_text, 'html.parser')
+
+        title = soup.title.string if soup.title is not None else None
+        description_tag = soup.find('meta', attrs={'name': 'description'})
+        description = description_tag['content'] if description_tag is not None else None
+    finally:
+        return WebsiteMetadata(url=url, title=title, description=description)
+
+
+def load_page(url: str):
+    r = requests.get(url)
+    return r.text

bookmarks/styles/bookmarks.scss

@@ -49,3 +49,10 @@ ul.bookmark-list {
     color: $alternative-color-dark;
   }
 }
+
+.bookmarks-form {
+
+  .form-icon.loading {
+    visibility: hidden;
+  }
+}

bookmarks/templates/bookmarks/form.html

@@ -1,5 +1,6 @@
 {% load widget_tweaks %}
 
+<div class="bookmarks-form">
     {% csrf_token %}
     <div class="form-group {% if form.url.errors %}has-error{% endif %}">
         <label for="{{ form.url.id_for_label }}" class="form-label">URL</label>
@@ -14,21 +15,28 @@
         <label for="{{ form.title.id_for_label }}" class="form-label">Tags</label>
         {{ form.tag_string|add_class:"form-input" }}
         <div class="form-input-hint">
-        Enter any number of tags separated by space and without the hash (#). If a tag does not exist it will be automatically created.
+            Enter any number of tags separated by space and <strong>without</strong> the hash (#). If a tag does not exist it will be
+            automatically created.
         </div>
         {{ form.tag_string.errors }}
     </div>
-<div class="form-group">
-    <label for="{{ form.title.id_for_label }}" class="form-label">Custom title</label>
+    <div class="form-group has-icon-right">
+        <label for="{{ form.title.id_for_label }}" class="form-label">Title</label>
+        <div class="has-icon-right">
             {{ form.title|add_class:"form-input" }}
+            <i class="form-icon loading"></i>
+        </div>
         <div class="form-input-hint">
             Optional, leave empty to use title from website.
         </div>
         {{ form.title.errors }}
     </div>
     <div class="form-group">
-    <label for="{{ form.description.id_for_label }}" class="form-label">Custom description</label>
+        <label for="{{ form.description.id_for_label }}" class="form-label">Description</label>
+        <div class="has-icon-right">
             {{ form.description|add_class:"form-input"|attr:"rows:4" }}
+            <i class="form-icon loading"></i>
+        </div>
         <div class="form-input-hint">
             Optional, leave empty to use description from website.
         </div>
@@ -38,3 +46,36 @@
         <input type="submit" value="Save" class="btn btn-primary mr-2">
         <a href="{% url 'bookmarks:index' %}" class="btn">Nevermind</a>
     </div>
+
+    <script type="application/javascript">
+        /**
+         * Pre-fill title and description placeholders with metadata from website as soon as URL changes
+         */
+        (function init() {
+            const urlInput = document.getElementById('{{ form.url.id_for_label }}');
+            const titleInput = document.getElementById('{{ form.title.id_for_label }}');
+            const descriptionInput = document.getElementById('{{ form.description.id_for_label }}');
+
+            urlInput.addEventListener('input', () => {
+                toggleIcon(titleInput, true);
+                toggleIcon(descriptionInput, true);
+
+                const websiteUrl = urlInput.value;
+                const requestUrl = `{% url 'bookmarks:api.website_metadata' %}?url=${websiteUrl}`;
+                fetch(requestUrl)
+                    .then(response => response.json())
+                    .then(metadata => {
+                        titleInput.setAttribute('placeholder', metadata.title || '');
+                        descriptionInput.setAttribute('placeholder', metadata.description || '');
+                        toggleIcon(titleInput, false);
+                        toggleIcon(descriptionInput, false);
+                    });
+            });
+
+            function toggleIcon(input, show) {
+                const icon = input.parentNode.querySelector('i.form-icon');
+                icon.style['visibility'] = show ? 'visible' : 'hidden';
+            }
+        })();
+    </script>
+</div>

bookmarks/urls.py

@@ -3,6 +3,7 @@ from django.urls import path
 from django.views.generic import RedirectView
 
 from . import views
+from .views import api
 
 app_name = 'bookmarks'
 urlpatterns = [
@@ -13,4 +14,6 @@ urlpatterns = [
     path('bookmarks/new', views.new, name='new'),
     path('bookmarks/<int:bookmark_id>/edit', views.edit, name='edit'),
     path('bookmarks/<int:bookmark_id>/remove', views.remove, name='remove'),
+    # API
+    path('api/website_metadata', api.website_metadata, name='api.website_metadata'),
 ]

bookmarks/views/api.py

@@ -0,0 +1,9 @@
+from django.http import JsonResponse
+
+from services.website_loader import load_website_metadata
+
+
+def website_metadata(request):
+    url = request.GET.get('url')
+    metadata = load_website_metadata(url)
+    return JsonResponse(metadata.to_dict())