implement DJ014

crates/ruff_linter/resources/test/fixtures/flake8_django/DJ014.py

@@ -0,0 +1,40 @@
+from django.urls import path
+from . import views
+
+# Errors - missing trailing slash
+urlpatterns = [
+    path("help", views.help_view),  # DJ014
+    path("about", views.about_view),  # DJ014
+    path("contact", views.contact_view),  # DJ014
+    path("api/users", views.users_view),  # DJ014
+    path("blog/posts", views.posts_view),  # DJ014
+]
+
+# OK - has trailing slash
+urlpatterns_ok = [
+    path("help/", views.help_view),
+    path("about/", views.about_view),
+    path("contact/", views.contact_view),
+    path("api/users/", views.users_view),
+    path("blog/posts/", views.posts_view),
+]
+
+# OK - just root path
+urlpatterns_root = [
+    path("/", views.index_view),
+    path("", views.home_view),
+]
+
+# OK - with path parameters
+urlpatterns_params = [
+    path("users/<int:id>/", views.user_detail),
+    path("posts/<slug:slug>/", views.post_detail),
+]
+
+# Mixed cases
+urlpatterns_mixed = [
+    path("good/", views.good_view),
+    path("bad", views.bad_view),  # DJ014
+    path("also-good/", views.also_good_view),
+    path("also-bad", views.also_bad_view),  # DJ014
+]

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

@@ -1181,6 +1181,9 @@ pub(crate) fn expression(expr: &Expr, checker: &Checker) {
             if checker.is_rule_enabled(Rule::DjangoLocalsInRenderFunction) {
                 flake8_django::rules::locals_in_render_function(checker, call);
             }
+            if checker.is_rule_enabled(Rule::DjangoURLPathWithoutTrailingSlash) {
+                flake8_django::rules::url_path_without_trailing_slash(checker, call);
+            }
             if checker.is_rule_enabled(Rule::UnsupportedMethodCallOnAll) {
                 flake8_pyi::rules::unsupported_method_call_on_all(checker, func);
             }

crates/ruff_linter/src/codes.rs

@@ -1100,6 +1100,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Flake8Django, "008") => rules::flake8_django::rules::DjangoModelWithoutDunderStr,
         (Flake8Django, "012") => rules::flake8_django::rules::DjangoUnorderedBodyContentInModel,
         (Flake8Django, "013") => rules::flake8_django::rules::DjangoNonLeadingReceiverDecorator,
+        (Flake8Django, "014") => rules::flake8_django::rules::DjangoURLPathWithoutTrailingSlash,
 
         // flynt
         // Reserved: (Flynt, "001") => Rule: :StringConcatenationToFString,

crates/ruff_linter/src/rules/flake8_django/mod.rs

@@ -18,6 +18,7 @@ mod tests {
     #[test_case(Rule::DjangoExcludeWithModelForm, Path::new("DJ006.py"))]
     #[test_case(Rule::DjangoAllWithModelForm, Path::new("DJ007.py"))]
     #[test_case(Rule::DjangoModelWithoutDunderStr, Path::new("DJ008.py"))]
+    #[test_case(Rule::DjangoURLPathWithoutTrailingSlash, Path::new("DJ014.py"))]
     #[test_case(Rule::DjangoUnorderedBodyContentInModel, Path::new("DJ012.py"))]
     #[test_case(Rule::DjangoNonLeadingReceiverDecorator, Path::new("DJ013.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {

crates/ruff_linter/src/rules/flake8_django/rules/mod.rs

@@ -5,6 +5,7 @@ pub(crate) use model_without_dunder_str::*;
 pub(crate) use non_leading_receiver_decorator::*;
 pub(crate) use nullable_model_string_field::*;
 pub(crate) use unordered_body_content_in_model::*;
+pub(crate) use url_path_without_trailing_slash::*;
 
 mod all_with_model_form;
 mod exclude_with_model_form;
@@ -13,3 +14,4 @@ mod model_without_dunder_str;
 mod non_leading_receiver_decorator;
 mod nullable_model_string_field;
 mod unordered_body_content_in_model;
+mod url_path_without_trailing_slash;

crates/ruff_linter/src/rules/flake8_django/rules/url_path_without_trailing_slash.rs

@@ -0,0 +1,104 @@
+use ruff_macros::{ViolationMetadata, derive_message_formats};
+use ruff_python_ast::{self as ast, Expr};
+use ruff_python_semantic::Modules;
+use ruff_text_size::Ranged;
+
+use crate::Violation;
+use crate::checkers::ast::Checker;
+
+/// ## What it does
+/// Checks that all Django URL route definitions using `django.urls.path()`
+/// end with a trailing slash.
+///
+/// ## Why is this bad?
+/// Django's convention is to use trailing slashes in URL patterns. This is
+/// enforced by the `APPEND_SLASH` setting (enabled by default), which
+/// redirects requests without trailing slashes to URLs with them. Omitting
+/// the trailing slash can lead to unnecessary redirects and inconsistent URL
+/// patterns throughout your application.
+///
+/// ## Example
+/// ```python
+/// from django.urls import path
+/// from . import views
+///
+/// urlpatterns = [
+///     path("help", views.help_view),  # Missing trailing slash
+///     path("about", views.about_view),  # Missing trailing slash
+/// ]
+/// ```
+///
+/// Use instead:
+/// ```python
+/// from django.urls import path
+/// from . import views
+///
+/// urlpatterns = [
+///     path("help/", views.help_view),
+///     path("about/", views.about_view),
+/// ]
+/// ```
+///
+/// ## References
+/// - [Django documentation: URL dispatcher](https://docs.djangoproject.com/en/stable/topics/http/urls/)
+#[derive(ViolationMetadata)]
+#[violation_metadata(preview_since = "v0.14.1")]
+pub(crate) struct DjangoURLPathWithoutTrailingSlash {
+    url_pattern: String,
+}
+
+impl Violation for DjangoURLPathWithoutTrailingSlash {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        let DjangoURLPathWithoutTrailingSlash { url_pattern } = self;
+        format!("URL route `{url_pattern}` is missing a trailing slash")
+    }
+}
+
+/// DJ014
+pub(crate) fn url_path_without_trailing_slash(checker: &Checker, call: &ast::ExprCall) {
+    if !checker.semantic().seen_module(Modules::DJANGO) {
+        return;
+    }
+
+    // Check if this is a call to django.urls.path
+    if !checker
+        .semantic()
+        .resolve_qualified_name(&call.func)
+        .is_some_and(|qualified_name| {
+            matches!(qualified_name.segments(), ["django", "urls", "path"])
+        })
+    {
+        return;
+    }
+
+    // Get the first argument (the route pattern)
+    let Some(route_arg) = call.arguments.args.first() else {
+        return;
+    };
+
+    // Check if it's a string literal
+    if let Expr::StringLiteral(ast::ExprStringLiteral { value, .. }) = route_arg {
+        let route = value.to_str();
+
+        // Skip empty strings
+        if route.is_empty() {
+            return;
+        }
+
+        // Skip route parameters (routes with angle brackets like "<int:id>")
+        // These are often at the end and shouldn't require trailing slashes
+        // Also skip routes that are just "/" or already end with "/"
+        if route == "/" || route.ends_with('/') {
+            return;
+        }
+
+        // Report diagnostic for routes without trailing slash
+        checker.report_diagnostic(
+            DjangoURLPathWithoutTrailingSlash {
+                url_pattern: route.to_string(),
+            },
+            route_arg.range(),
+        );
+    }
+}

crates/ruff_linter/src/rules/flake8_django/snapshots/ruff_linter__rules__flake8_django__tests__DJ014_DJ014.py.snap

@@ -0,0 +1,77 @@
+---
+source: crates/ruff_linter/src/rules/flake8_django/mod.rs
+---
+DJ014 URL route `help` is missing a trailing slash
+ --> DJ014.py:6:10
+  |
+4 | # Errors - missing trailing slash
+5 | urlpatterns = [
+6 |     path("help", views.help_view),  # DJ014
+  |          ^^^^^^
+7 |     path("about", views.about_view),  # DJ014
+8 |     path("contact", views.contact_view),  # DJ014
+  |
+
+DJ014 URL route `about` is missing a trailing slash
+ --> DJ014.py:7:10
+  |
+5 | urlpatterns = [
+6 |     path("help", views.help_view),  # DJ014
+7 |     path("about", views.about_view),  # DJ014
+  |          ^^^^^^^
+8 |     path("contact", views.contact_view),  # DJ014
+9 |     path("api/users", views.users_view),  # DJ014
+  |
+
+DJ014 URL route `contact` is missing a trailing slash
+  --> DJ014.py:8:10
+   |
+ 6 |     path("help", views.help_view),  # DJ014
+ 7 |     path("about", views.about_view),  # DJ014
+ 8 |     path("contact", views.contact_view),  # DJ014
+   |          ^^^^^^^^^
+ 9 |     path("api/users", views.users_view),  # DJ014
+10 |     path("blog/posts", views.posts_view),  # DJ014
+   |
+
+DJ014 URL route `api/users` is missing a trailing slash
+  --> DJ014.py:9:10
+   |
+ 7 |     path("about", views.about_view),  # DJ014
+ 8 |     path("contact", views.contact_view),  # DJ014
+ 9 |     path("api/users", views.users_view),  # DJ014
+   |          ^^^^^^^^^^^
+10 |     path("blog/posts", views.posts_view),  # DJ014
+11 | ]
+   |
+
+DJ014 URL route `blog/posts` is missing a trailing slash
+  --> DJ014.py:10:10
+   |
+ 8 |     path("contact", views.contact_view),  # DJ014
+ 9 |     path("api/users", views.users_view),  # DJ014
+10 |     path("blog/posts", views.posts_view),  # DJ014
+   |          ^^^^^^^^^^^^
+11 | ]
+   |
+
+DJ014 URL route `bad` is missing a trailing slash
+  --> DJ014.py:37:10
+   |
+35 | urlpatterns_mixed = [
+36 |     path("good/", views.good_view),
+37 |     path("bad", views.bad_view),  # DJ014
+   |          ^^^^^
+38 |     path("also-good/", views.also_good_view),
+39 |     path("also-bad", views.also_bad_view),  # DJ014
+   |
+
+DJ014 URL route `also-bad` is missing a trailing slash
+  --> DJ014.py:39:10
+   |
+37 |     path("bad", views.bad_view),  # DJ014
+38 |     path("also-good/", views.also_good_view),
+39 |     path("also-bad", views.also_bad_view),  # DJ014
+   |          ^^^^^^^^^^
+40 | ]
+   |

ruff.schema.json

@@ -3157,6 +3157,7 @@
         "DJ01",
         "DJ012",
         "DJ013",
+        "DJ014",
         "DOC",
         "DOC1",
         "DOC10",