Fixed #1682 -- alert user when using file field without proper encoding

debug_toolbar/panels/alerts.py

@@ -0,0 +1,95 @@
+from html.parser import HTMLParser
+
+from django.utils.translation import gettext_lazy as _
+
+from debug_toolbar.panels import Panel
+
+
+class FormParser(HTMLParser):
+    """
+    HTML form parser, used to check for invalid configurations of forms that
+    take file inputs.
+    """
+
+    def __init__(self):
+        super().__init__()
+        self.in_form = False
+        self.current_form = {}
+        self.forms = []
+
+    def handle_starttag(self, tag, attrs):
+        attrs = dict(attrs)
+        if tag == "form":
+            self.in_form = True
+            self.current_form = {
+                "file_form": False,
+                "form_attrs": attrs,
+                "submit_element_attrs": [],
+            }
+        elif self.in_form and tag == "input" and attrs.get("type") == "file":
+            self.current_form["file_form"] = True
+        elif self.in_form and (
+            (tag == "input" and attrs.get("type") in {"submit", "image"})
+            or tag == "button"
+        ):
+            self.current_form["submit_element_attrs"].append(attrs)
+
+    def handle_endtag(self, tag):
+        if tag == "form" and self.in_form:
+            self.forms.append(self.current_form)
+            self.in_form = False
+
+
+class AlertsPanel(Panel):
+    """
+    A panel to alert users to issues.
+    """
+
+    title = _("Alerts")
+
+    template = "debug_toolbar/panels/alerts.html"
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.issues = []
+
+    @property
+    def nav_subtitle(self):
+        if self.issues:
+            issue_text = "issue" if len(self.issues) == 1 else "issues"
+            return f"{len(self.issues)} {issue_text} found"
+        else:
+            return ""
+
+    def add_issue(self, issue):
+        self.issues.append(issue)
+
+    def check_invalid_file_form_configuration(self, html_content):
+        parser = FormParser()
+        parser.feed(html_content)
+
+        for form in parser.forms:
+            if (
+                form["file_form"]
+                and form["form_attrs"].get("enctype") != "multipart/form-data"
+                and not any(
+                    elem.get("formenctype") == "multipart/form-data"
+                    for elem in form["submit_element_attrs"]
+                )
+            ):
+                form_id = form["form_attrs"].get("id", "no form id")
+                issue = (
+                    f'Form with id "{form_id}" contains file input but '
+                    "does not have multipart/form-data encoding."
+                )
+                self.add_issue({"issue": issue})
+        return self.issues
+
+    def generate_stats(self, request, response):
+        html_content = response.content.decode(response.charset)
+        self.check_invalid_file_form_configuration(html_content)
+
+        # Further issue checks can go here
+
+        # Write all issues to record_stats
+        self.record_stats({"issues": self.issues})

debug_toolbar/settings.py

@@ -58,6 +58,7 @@ def get_config():
 
 
 PANELS_DEFAULTS = [
+    "debug_toolbar.panels.alerts.AlertsPanel",
     "debug_toolbar.panels.history.HistoryPanel",
     "debug_toolbar.panels.versions.VersionsPanel",
     "debug_toolbar.panels.timer.TimerPanel",

debug_toolbar/templates/debug_toolbar/panels/alerts.html

@@ -0,0 +1,12 @@
+{% load i18n %}
+
+{% if issues %}
+  <h4>{% trans "Issues found" %}</h4>
+  {% for issue in issues %}
+    <ul>
+      <li>{{ issue.issue }}</li>
+    </ul>
+  {% endfor %}
+{% else %}
+  <p>No issues found.</p>
+{% endif %}

docs/changes.rst

@@ -4,6 +4,8 @@ Change log
 Pending
 -------
 
+* Added alert panel with warning when form is using file fields
+  without proper encoding type.
 * Fixed overriding font-family for both light and dark themes.
 * Restored compatibility with ``iptools.IpRangeList``.
 

docs/configuration.rst

@@ -20,6 +20,7 @@ included in the toolbar. It works like Django's ``MIDDLEWARE`` setting. The
 default value is::
 
     DEBUG_TOOLBAR_PANELS = [
+        'debug_toolbar.panels.alerts.AlertsPanel',
         'debug_toolbar.panels.history.HistoryPanel',
         'debug_toolbar.panels.versions.VersionsPanel',
         'debug_toolbar.panels.timer.TimerPanel',

docs/panels.rst

@@ -9,6 +9,15 @@ Default built-in panels
 
 The following panels are enabled by default.
 
+Alerts
+~~~~~~~
+
+.. class:: debug_toolbar.panels.alerts.AlertsPanel
+
+This panel shows alerts for a set of pre-defined issues. Currently, the only
+issue it checks for is the encoding of a form that takes a file input not
+being set to ``multipart/form-data``.
+
 History
 ~~~~~~~
 

tests/panels/test_alerts.py

@@ -0,0 +1,57 @@
+from django.http import HttpResponse
+from django.template import Context, Template
+
+from ..base import BaseTestCase
+
+
+class AlertsPanelTestCase(BaseTestCase):
+    panel_id = "AlertsPanel"
+
+    def test_issue_warning_display(self):
+        """
+        Test that the panel (does not) display[s] a warning when there are
+        (no) issues.
+        """
+        self.panel.issues = 0
+        nav_subtitle = self.panel.nav_subtitle
+        self.assertNotIn("issues found", nav_subtitle)
+
+        self.panel.issues = ["Issue 1", "Issue 2"]
+        nav_subtitle = self.panel.nav_subtitle
+        self.assertIn("2 issues found", nav_subtitle)
+
+    def test_file_form_without_enctype_multipart_form_data(self):
+        """
+        Test that the panel displays a form invalid message when there is
+        a file input but encoding not set to multipart/form-data.
+        """
+        test_form = '<form id="test-form"><input type="file"></form>'
+        result = self.panel.check_invalid_file_form_configuration(test_form)
+        expected_error = (
+            'Form with id "test-form" contains file input '
+            "but does not have multipart/form-data encoding."
+        )
+        self.assertEqual(result[0]["issue"], expected_error)
+        self.assertEqual(len(result), 1)
+
+    def test_file_form_with_enctype_multipart_form_data(self):
+        test_form = """<form id="test-form" enctype="multipart/form-data">
+        <input type="file">
+        </form>"""
+        result = self.panel.check_invalid_file_form_configuration(test_form)
+
+        self.assertEqual(len(result), 0)
+
+    def test_integration_file_form_without_enctype_multipart_form_data(self):
+        t = Template('<form id="test-form"><input type="file"></form>')
+        c = Context({})
+        rendered_template = t.render(c)
+        response = HttpResponse(content=rendered_template)
+
+        self.panel.generate_stats(self.request, response)
+
+        self.assertIn(
+            "Form with id &quot;test-form&quot; contains file input "
+            "but does not have multipart/form-data encoding.",
+            self.panel.content,
+        )

tests/panels/test_history.py

@@ -67,6 +67,7 @@ def test_urls(self):
 @override_settings(DEBUG=True)
 class HistoryViewsTestCase(IntegrationTestCase):
     PANEL_KEYS = {
+        "AlertsPanel",
         "VersionsPanel",
         "TimerPanel",
         "SettingsPanel",