feat: Set ChangeFreq and Priority via metadata (#30)

README.md

@@ -84,6 +84,26 @@ SITEMAP = {
 }
 ```
 
+Using Metadata
+--------------
+
+In addition to applying a configuration to all articles/pages using the `SITEMAP` setting, `ChangeFreq` and `Priority` can also be specified as metadata for individual articles/pages. The same restrictions on the values apply:
+
+* Valid options for `ChangeFreq` are  `always`, `hourly`, `daily`, `weekly`, `monthly`, `yearly` and `never`.
+* Valid options for `Priority` must be a decimal number between `0` and `1`.
+
+**Example**
+
+Following is an example of using sitemap-related metadata in a Markdown file:
+
+```
+Title: Frequently Changed Article
+ChangeFreq: daily
+Priority: 0.3
+
+This is the article content.
+```
+
 Contributing
 ------------
 

pelican/plugins/sitemap/sitemap.py

@@ -156,8 +156,23 @@ def is_excluded(item):
                     if isinstance(obj, contents.Page)
                     else "indexes"
                 )
-                changefreq = changefreqs[content_type]
-                priority = float(priorities[content_type])
+
+                # see if changefreq specified in metadata headers; fall back to config
+                changefreq = getattr(obj, "changefreq", changefreqs[content_type])
+                if changefreq not in CHANGEFREQ_VALUES:
+                    log.error(f"sitemap: Invalid 'changefreqs' value: {changefreq!r}")
+                    changefreq = changefreqs[content_type]
+
+                # see if priority specified in metadata headers; fall back to config
+                priority_raw = getattr(obj, "priority", priorities[content_type])
+                try:
+                    priority = float(priority_raw)
+                except ValueError:
+                    log.exception(
+                        f"sitemap: Require numeric priority. Got: {priority_raw!r}"
+                    )
+                    priority = priorities[content_type]
+
                 translations = "".join(
                     XML_TRANSLATION.format(
                         trans.lang,

pelican/plugins/sitemap/test_data/article2.md

@@ -0,0 +1,9 @@
+Title: Test post daily
+Date: 2023-07-12 13:00:00
+Category: test
+Tags: foo, bar, foobar
+Summary: Daily testing is my main function in life.
+ChangeFreq: daily
+Priority: 0.3
+
+This is the article content.

pelican/plugins/sitemap/test_sitemap.py

@@ -53,6 +53,7 @@ def test_txt(self):
 http://localhost/tag/foo.html
 http://localhost/tag/foobar.html
 http://localhost/tags.html
+http://localhost/test-post-daily.html
 http://localhost/test-post.html
 """
         self.assertEqual(expected, contents)
@@ -68,5 +69,15 @@ def test_xml(self):
 <changefreq>monthly</changefreq>
 <priority>0.5</priority>
 </url>
+"""
+        self.assertIn(needle, contents)
+
+        needle = """\
+<url>
+<loc>http://localhost/test-post-daily.html</loc>
+<lastmod>2023-07-12T13:00:00+00:00</lastmod>
+<changefreq>daily</changefreq>
+<priority>0.3</priority>
+</url>
 """
         self.assertIn(needle, contents)