add: pipeline categorization by metadata key

examples/basic/Cabretfile.yaml

@@ -10,5 +10,14 @@ build:
       - use: layout
         path: layouts/base.html
       - target: dist/posts/{id}/index.html
-
+  - pipeline:
+      - source: posts/{id}.md
+      - use: frontmatter
+      - use: categorize
+        key: tags
+      - use: layout
+        path: layouts/tag.html
+      - use: layout
+        path: layouts/base.html
+      - target: dist/tags/{{ .Category }}/index.html
 

examples/basic/layouts/base.html

@@ -7,6 +7,6 @@
         <title>{{- if .Title -}}{{ .Title }} | {{ else }}{{ end -}} My Blog</title>
     </head>
     <body>
-        {{- .Content -}}
+        {{ .Content }}
     </body>
 </html>

examples/basic/layouts/tag.html

@@ -0,0 +1,12 @@
+<h1>Tag #{{ .Category }}</h1>
+
+<p>Here are the posts with this tag</p>
+
+<ul>
+    {{ range .Items }}
+    <li>
+        <p>{{ .Metadata.Title }}</p>
+        <pre><code>{{ .Metadata.MatchResult }}</code></pre>
+    </li>
+    {{ end }}
+</ul>

examples/basic/posts/post-1.md

@@ -2,6 +2,7 @@
 title: First Post
 description: Lorem ipsum dolor sit amet consectetur adipisicing elit.
 publish_date: 2022-12-22 11:00
+tags: [a, b]
 ---
 
 # First Post

examples/basic/posts/post-2.md

@@ -2,6 +2,7 @@
 title: Second Post
 description: Lorem ipsum dolor sit amet consectetur adipisicing elit.
 publish_date: 2022-12-22 11:00
+tags: [b, c]
 ---
 
 # Second Post

examples/basic/posts/post-3.md

@@ -2,6 +2,7 @@
 title: Third Post
 description: Lorem ipsum dolor sit amet consectetur adipisicing elit.
 publish_date: 2022-12-22 11:00
+tags: [a]
 ---
 
 # Third Post