Add Content#relative_path which returns a file's relative path with…

…in its collection (#7)

CHANGELOG.md

@@ -1,8 +1,12 @@
 # CHANGELOG
 
+## Unreleased
+
+- Add `Content#relative_path` which returns a file's relative path within its collection.
+
 ## Version 0.2.0 - 2024-10-13
 
-- Add support for a content instance knowing its own `#slug` - its relative path within its collection:
+- Add support for a content instance knowing its own `#slug` - its extension-less relative path within its collection:
 
   ```ruby
   Page = Decant.define(dir: 'content', ext: 'md')

lib/decant/collection.rb

@@ -44,13 +44,22 @@ def glob(pattern)
       dir.glob("#{pattern}#{ext}").select { |path| path.file? }
     end
 
+    # The relative path of +path+ within {#dir}.
+    #
+    # @param path [Pathname]
+    #
+    # @return [String]
+    def relative_path_for(path)
+      path.relative_path_from(dir).to_s
+    end
+
     # The extension-less relative path of +path+ within {#dir}.
     #
     # @param path [Pathname]
     #
     # @return [String]
     def slug_for(path)
-      relative_path = path.relative_path_from(dir).to_s
+      relative_path = relative_path_for(path)
 
       # The collection has no configured extension, files are identified by
       # their full (relative) path so there's no extension to remove.

lib/decant/content.rb

@@ -49,6 +49,20 @@ def frontmatter(*attrs)
       end
     end
 
+    # The relative path of the file within its collection.
+    #
+    # @example
+    #   Page = Decant.define(dir: 'content', ext: 'md')
+    #
+    #   page = Page.find('features/slugs')
+    #   page.path.expand_path # => "/Users/dave/my-website/content/features/slugs.md"
+    #   page.relative_path    # => "features/slugs.md"
+    #
+    # @return [String]
+    def relative_path
+      self.class.collection.relative_path_for(path)
+    end
+
     # The extension-less relative path of the file within its collection.
     #
     # @example

spec/decant/collection_spec.rb

@@ -220,6 +220,33 @@
     end
   end
 
+  context '#relative_path_for' do
+    let(:collection) { described_class.new(dir: dir, ext: ext) }
+    let(:dir) { Pathname.new('/tmp/not-a-real-path') }
+
+    def relative_path_for(path)
+      collection.relative_path_for(dir.join(path))
+    end
+
+    context 'when #ext is not defined' do
+      let(:ext) { nil }
+
+      it 'includes the extension' do
+        expect(relative_path_for('foo.txt')).to eql('foo.txt')
+        expect(relative_path_for('foo/bar.txt')).to eql('foo/bar.txt')
+      end
+    end
+
+    context 'when #ext is defined' do
+      let(:ext) { '.md' }
+
+      it 'returns the relative path' do
+        expect(relative_path_for('foo.md')).to eql('foo.md')
+        expect(relative_path_for('foo/bar.md')).to eql('foo/bar.md')
+      end
+    end
+  end
+
   context '#slug_for' do
     let(:collection) { described_class.new(dir: dir, ext: ext) }
     let(:dir) { Pathname.new('/tmp/not-a-real-path') }

spec/decant/content_spec.rb

@@ -90,10 +90,20 @@
     end
   end
 
+  describe '#relative_path' do
+    let(:klass) { Decant.define(dir: tmpdir, ext: '.md') }
+
+    it 'is the relative path within its collection' do
+      file('foo/bar.md')
+      instance = klass.find('foo/*')
+      expect(instance.relative_path).to eql('foo/bar.md')
+    end
+  end
+
   describe '#slug' do
     let(:klass) { Decant.define(dir: tmpdir, ext: '.md') }
 
-    it 'is the relative path within its collection excluding the extension' do
+    it 'is the extension-less relative path within its collection' do
       file('foo/bar.md')
       instance = klass.find('foo/*')
       expect(instance.slug).to eql('foo/bar')