Changement du refresh handler, soft reset d'ajouter sur beaucoup de formulaire de modification

app/responders.py

@@ -0,0 +1,84 @@
+"""Helpers for mutating routes that should not force a full page reload.
+
+The site is server-rendered, and every mutating route used to end with
+``return redirect(url_for(...))``, so each change reloaded the whole page:
+scroll reset, open dialogs closed, and chaining several edits meant waiting
+for a full render between each one.
+
+These helpers let a route answer an AJAX submit (the ``data-ajax`` forms in
+main.js) with a small JSON payload instead of a redirect, while the plain
+HTML form path keeps behaving exactly as before. The client then fetches the
+page again and swaps only the content region, so the page never reloads.
+
+The counterpart that performs the swap lives in app/static/js/main.js.
+"""
+
+from flask import get_flashed_messages, jsonify, redirect, request, session
+
+from app.models import AppSettings
+
+#: Key holding a coarse, monotonically increasing stamp for the whole dataset.
+#: It advances after every committed mutation so a stale client can be told
+#: (with a 409) that someone else has changed what it is looking at.
+REVISION_KEY = 'data_revision'
+
+
+def is_ajax_submit():
+    """Whether this POST came from the fetch-based form handler in main.js."""
+    return request.headers.get('X-Requested-With') == 'XMLHttpRequest'
+
+
+def current_revision():
+    """The current revision stamp, as an int (0 when nothing has been bumped)."""
+    try:
+        return int(AppSettings.get(REVISION_KEY, '0') or '0')
+    except (TypeError, ValueError):
+        return 0
+
+
+def bump_revision():
+    """Advance the revision stamp after a committed change.
+
+    Stored through AppSettings so it survives restarts and is shared by every
+    worker, unlike a module-level counter.
+    """
+    AppSettings.set(REVISION_KEY, str(current_revision() + 1))
+
+
+def _flashed_success():
+    """Whether a success flash is pending, without consuming it.
+
+    The HTML path still redirects and must leave the flash for the next page
+    to render; peeking at the session is the only way to know without clearing
+    it. Only a successful commit advances the revision -- a rejected edit must
+    not make other users reload for nothing.
+    """
+    flashes = session.get('_flashes', [])
+    return any(category == 'success' for category, _message in flashes)
+
+
+def respond_after_change(redirect_url):
+    """Answer a committed (or rejected) mutation.
+
+    For a normal HTML form submit this is exactly the ``redirect(...)`` the
+    routes used to return. For an AJAX submit it returns JSON telling the
+    client where to fetch the refreshed fragment and which flash messages to
+    show, so the page can update in place instead of reloading.
+    """
+    if _flashed_success():
+        bump_revision()
+
+    if is_ajax_submit():
+        messages = [
+            {'category': category, 'text': message}
+            for category, message in get_flashed_messages(with_categories=True)
+        ]
+        return jsonify(
+            {
+                'ok': True,
+                'redirect': redirect_url,
+                'messages': messages,
+                'revision': current_revision(),
+            }
+        )
+    return redirect(redirect_url)