初步完成

app/Http/Controllers/ArticleController.php

@@ -16,8 +16,10 @@ class ArticleController extends Controller
      */
     public function show(Article $article)
     {
-        $category = $article->category;
-        $parent   = getTopCate($category->id);
+        $parent = $category = $article->category;
+        if ($category->id) {
+            $parent = getTopCate($category->id);
+        }
 
         $next = Article::where('id', '>', $article->id)
                        ->where('category_id', $article->category_id)
@@ -36,6 +38,7 @@ class ArticleController extends Controller
                            ->when($title, function ($q) use ($title) {
                                $q->where('title', 'like', "%{$title}%");
                            })
+                           ->where('category_id', '>', 0)
                            ->paginate();
 
         return view('article.search', compact('articles'));