Feed by tag (#264)

Merge pull request 264

README.md

@@ -205,6 +205,44 @@ feed:
 The same flag can be used directly in post file. It will be disable `<content>` tag for selected post.
 Settings in post file has higher priority than in config file.
 
+## Tags
+
+To automatically generate feeds for each tag you apply to your posts you can add a tags setting to your config:
+
+```yml
+feed:
+  tags: true
+```
+
+If there are tags you don't want included in this auto generation you can exclude them
+
+```yml
+feed:
+  tags:
+    except:
+      - tag-to-exclude
+      - another-tag
+```
+
+If you wish to change the location of these auto generated feeds (`/feed/by_tag/<TAG>.xml` by default) you can provide an alternative folder for them to live in.
+
+```yml
+feed:
+  tags:
+    path: "alternative/path/for/tags/feeds/"
+```
+
+If you only want to generate feeds for a few tags you can also set this.
+
+```yml
+feed:
+  tags:
+    only:
+      - tag-to-include
+      - another-tag
+```
+
+Note that if you include a tag that is excluded a feed will not be generated for it.
 
 ## Contributing
 

lib/jekyll-feed/feed.xml

@@ -39,7 +39,12 @@
     </author>
   {% endif %}
 
-  {% assign posts = site[page.collection] | where_exp: "post", "post.draft != true" | sort: "date" | reverse %}
+  {% if page.tags %}
+    {% assign entries = site.tags[page.tags] %}
+  {% else %}
+    {% assign entries = site[page.collection] %}
+  {% endif %}
+  {% assign posts = entries | where_exp: "post", "post.draft != true" | sort: "date" | reverse %}
   {% if page.category %}
     {% assign posts = posts | where: "category",page.category %}
   {% endif %}

lib/jekyll-feed/generator.rb

@@ -17,6 +17,7 @@ def generate(site)
           @site.pages << make_page(path, :collection => name, :category => category)
         end
       end
+      generate_feed_by_tag if config["tags"] && !@site.tags.empty?
     end
 
     private
@@ -69,6 +70,32 @@ def collections
       @collections
     end
 
+    def generate_feed_by_tag
+      tags_config = config["tags"]
+      tags_config = {} unless tags_config.is_a?(Hash)
+
+      except    = tags_config["except"] || []
+      only      = tags_config["only"] || @site.tags.keys
+      tags_pool = only - except
+      tags_path = tags_config["path"] || "/feed/by_tag/"
+
+      generate_tag_feed(tags_pool, tags_path)
+    end
+
+    def generate_tag_feed(tags_pool, tags_path)
+      tags_pool.each do |tag|
+        # allow only tags with basic alphanumeric characters and underscore to keep
+        # feed path simple.
+        next if tag =~ %r![^a-zA-Z0-9_]!
+
+        Jekyll.logger.info "Jekyll Feed:", "Generating feed for posts tagged #{tag}"
+        path = "#{tags_path}#{tag}.xml"
+        next if file_exists?(path)
+
+        @site.pages << make_page(path, :tags => tag)
+      end
+    end
+
     # Path to feed.xml template file
     def feed_source_path
       @feed_source_path ||= File.expand_path "feed.xml", __dir__
@@ -85,15 +112,16 @@ def file_exists?(file_path)
 
     # Generates contents for a file
 
-    def make_page(file_path, collection: "posts", category: nil)
+    def make_page(file_path, collection: "posts", category: nil, tags: nil)
       PageWithoutAFile.new(@site, __dir__, "", file_path).tap do |file|
         file.content = feed_template
         file.data.merge!(
           "layout"     => nil,
           "sitemap"    => false,
           "xsl"        => file_exists?("feed.xslt.xml"),
           "collection" => collection,
-          "category"   => category
+          "category"   => category,
+          "tags"       => tags
         )
         file.output
       end

spec/fixtures/_posts/2013-12-12-dec-the-second.md

@@ -2,6 +2,8 @@
 excerpt: "Foo"
 image: "/image.png"
 category: news
+tags:
+ - test
 ---
 
 # December the twelfth, actually.

spec/fixtures/_posts/2014-03-02-march-the-second.md

@@ -1,6 +1,8 @@
 ---
 image: https://cdn.example.org/absolute.png?h=188&w=250
 category: news
+tags:
+ - test
 ---
 
 March the second!

spec/fixtures/_posts/2014-03-04-march-the-fourth.md

@@ -2,6 +2,7 @@
 title: <span class="highlight">Sparkling</span> Title
 tags:
  - '"/><VADER>'
+ - test
 image:
   path: "/object-image.png"
 categories: updates jekyll

spec/fixtures/_posts/2015-01-18-jekyll-last-modified-at.md

@@ -1,5 +1,8 @@
 ---
 last_modified_at: 2015-05-12T13:27:59+00:00
+tags:
+ - test
+ - fail
 ---
 
 Please don't modify this file. It's modified time is important.

spec/fixtures/_posts/2015-05-12-pre.html

@@ -1,6 +1,8 @@
 ---
 author: Pat
 lang: en
+tags:
+ - test
 ---
 
 <pre>Line 1

spec/fixtures/_posts/2015-05-18-author-detail.md

@@ -4,6 +4,9 @@ author:
   name: Ben
   uri: "http://ben.balter.com"
   email: ben@example.com
+tags:
+ - test
+ - success
 ---
 
 # December the twelfth, actually.

spec/fixtures/_posts/2015-08-08-stuck-in-the-middle.html

@@ -1,4 +1,7 @@
 ---
+tags:
+ - test
+ - fail
 feed:
   excerpt_only: true
 ---

spec/jekyll-feed_spec.rb

@@ -497,6 +497,141 @@
     end
   end
 
+  context "tags" do
+    let(:tags_feed_test) { File.read(dest_dir("feed/by_tag/test.xml")) }
+    let(:tags_feed_fail) { File.read(dest_dir("feed/by_tag/fail.xml")) }
+    let(:tags_feed_success) { File.read(dest_dir("feed/by_tag/success.xml")) }
+
+
+    context "do not set tags setting" do
+      it "should not write tags feeds" do
+        expect(Pathname.new(dest_dir("feed/by_tag/test.xml"))).to_not exist
+        expect(Pathname.new(dest_dir("feed/by_tag/fail.xml"))).to_not exist
+        expect(Pathname.new(dest_dir("feed/by_tag/success.xml"))).to_not exist
+      end
+    end
+
+    context "set tags setting" do
+      let(:overrides) do
+        {
+          "feed" => {
+            "tags" => true
+          },
+        }
+      end
+
+      it "should write tags feeds" do
+        expect(Pathname.new(dest_dir("feed/by_tag/test.xml"))).to exist
+        expect(Pathname.new(dest_dir("feed/by_tag/fail.xml"))).to exist
+        expect(Pathname.new(dest_dir("feed/by_tag/success.xml"))).to exist
+
+        expect(tags_feed_test).to match "/2013/12/12/dec-the-second.html"
+        expect(tags_feed_test).to match "/2014/03/02/march-the-second.html"
+        expect(tags_feed_test).to match "/2014/03/04/march-the-fourth.html"
+        expect(tags_feed_test).to match "/2015/01/18/jekyll-last-modified-at.html"
+        expect(tags_feed_test).to match "/2015/05/12/pre.html"
+        expect(tags_feed_test).to match "/2015/05/18/author-detail.html"
+        expect(tags_feed_test).to match "/2015/08/08/stuck-in-the-middle.html"
+
+        expect(tags_feed_fail).to match "/2015/01/18/jekyll-last-modified-at.html"
+        expect(tags_feed_fail).to match "/2015/08/08/stuck-in-the-middle.html"
+        expect(tags_feed_fail).to_not match "/2013/12/12/dec-the-second.html"
+        expect(tags_feed_fail).to_not match "/2014/03/02/march-the-second.html"
+        expect(tags_feed_fail).to_not match "/2014/03/04/march-the-fourth.html"
+        expect(tags_feed_fail).to_not match "/2015/05/12/pre.html"
+        expect(tags_feed_fail).to_not match "/2015/05/18/author-detail.html"
+
+        expect(tags_feed_success).to match "2015/05/18/author-detail.html"
+        expect(tags_feed_success).to_not match "/2013/12/12/dec-the-second.html"
+        expect(tags_feed_success).to_not match "/2014/03/02/march-the-second.html"
+        expect(tags_feed_success).to_not match "/2014/03/04/march-the-fourth.html"
+        expect(tags_feed_success).to_not match "/2015/01/18/jekyll-last-modified-at.html"
+        expect(tags_feed_success).to_not match "/2015/05/12/pre.html"
+        expect(tags_feed_success).to_not match "/2015/08/08/stuck-in-the-middle.html"
+      end
+    end
+
+    context "set exclusions" do
+      let(:overrides) do
+        {
+          "feed" => {
+            "tags" => {
+              "except" => ["fail"]
+            },
+          },
+        }
+      end
+
+      it "should not write fail feed" do
+        expect(Pathname.new(dest_dir("feed/by_tag/test.xml"))).to exist
+        expect(Pathname.new(dest_dir("feed/by_tag/fail.xml"))).to_not exist
+        expect(Pathname.new(dest_dir("feed/by_tag/success.xml"))).to exist
+      end
+    end
+
+    context "set inclusions" do
+      let(:overrides) do
+        {
+          "feed" => {
+            "tags" => {
+              "only" => ["success"]
+            },
+          },
+        }
+      end
+
+      it "should not write fail feed" do
+        expect(Pathname.new(dest_dir("feed/by_tag/test.xml"))).to_not exist
+        expect(Pathname.new(dest_dir("feed/by_tag/fail.xml"))).to_not exist
+        expect(Pathname.new(dest_dir("feed/by_tag/success.xml"))).to exist
+      end
+    end
+
+    context "set alternate path" do
+      let(:overrides) do
+        {
+          "feed" => {
+            "tags" => {
+              "path" => "alternate/path/"
+            },
+          },
+        }
+      end
+
+      it "should write feeds to new path" do
+        expect(Pathname.new(dest_dir("feed/by_tag/test.xml"))).to_not exist
+        expect(Pathname.new(dest_dir("feed/by_tag/fail.xml"))).to_not exist
+        expect(Pathname.new(dest_dir("feed/by_tag/success.xml"))).to_not exist
+
+        expect(Pathname.new(dest_dir("alternate/path/test.xml"))).to exist
+        expect(Pathname.new(dest_dir("alternate/path/fail.xml"))).to exist
+        expect(Pathname.new(dest_dir("alternate/path/success.xml"))).to exist
+      end
+
+      context "set to questionable path" do
+        let(:overrides) do
+          {
+            "feed" => {
+              "tags" => {
+                "path" => "../../../../../../../questionable/path/"
+              },
+            },
+          }
+        end
+
+        it "should write feeds to sane paths" do
+          expect(Pathname.new(dest_dir("feed/by_tag/test.xml"))).to_not exist
+          expect(Pathname.new(dest_dir("feed/by_tag/fail.xml"))).to_not exist
+          expect(Pathname.new(dest_dir("feed/by_tag/success.xml"))).to_not exist
+
+          expect(Pathname.new(dest_dir("questionable/path/test.xml"))).to exist
+          expect(Pathname.new(dest_dir("questionable/path/fail.xml"))).to exist
+          expect(Pathname.new(dest_dir("questionable/path/success.xml"))).to exist
+        end
+      end
+    end
+  end
+
   context "excerpt_only flag" do
     context "backward compatibility for no excerpt_only flag" do
       it "should be in contents" do