Add Page.GetTerms

Fixes #6905

8 files changed, 82 insertions, 15 deletions

diff --git a/docs/content/en/templates/taxonomy-templates.md b/docs/content/en/templates/taxonomy-templates.md
index b82a5175c..bef2d3226 100644
--- a/docs/content/en/templates/taxonomy-templates.md
+++ b/docs/content/en/templates/taxonomy-templates.md
@@ -216,6 +216,18 @@ Because we are leveraging the front matter system to define taxonomies for conte
 
 ### Example: List Tags in a Single Page Template
 
+{{< new-in "0.65.0" >}}
+
+```go-html-template
+<ul>
+    {{ range (.GetTerms "tags") }}
+        <li><a href="{{ .Permalink }}">{{ .LinkTitle }}</a></li>
+   {{ end }}
+</ul>
+```
+
+Before Hugo 0.65.0 you needed to do something like this:
+
 ```go-html-template
 {{ $taxo := "tags" }} <!-- Use the plural form here -->
 <ul id="{{ $taxo }}">
diff --git a/hugolib/content_map_page.go b/hugolib/content_map_page.go
index 06d1310ec..5075095ea 100644
--- a/hugolib/content_map_page.go
+++ b/hugolib/content_map_page.go
@@ -599,7 +599,7 @@ func (m *pageMap) attachPageToViews(s string, b *contentNode) {
 
 			if s == "/" {
 				// To avoid getting an empty key.
-				s = "home"
+				s = page.KindHome
 			}
 			key := cleanTreeKey(path.Join(viewName.plural, termKey, s))
 			m.taxonomyEntries.Insert(key, bv)
diff --git a/hugolib/page.go b/hugolib/page.go
index 1384d7293..12129d4ad 100644
--- a/hugolib/page.go
+++ b/hugolib/page.go
@@ -131,6 +131,34 @@ func (p *pageState) GitInfo() *gitmap.GitInfo {
 	return p.gitInfo
 }
 
+// GetTerms gets the terms defined on this page in the given taxonomy.
+func (p *pageState) GetTerms(taxonomy string) page.Pages {
+	taxonomy = strings.ToLower(taxonomy)
+	m := p.s.pageMap
+	prefix := cleanTreeKey(taxonomy)
+
+	var self string
+	if p.IsHome() {
+		// TODO(bep) make this less magical, see taxonomyEntries.Insert.
+		self = "/" + page.KindHome
+	} else {
+		self = p.treeRef.key
+	}
+
+	var pas page.Pages
+
+	m.taxonomies.WalkPrefixListable(prefix, func(s string, n *contentNode) bool {
+		if _, found := m.taxonomyEntries.Get(s + self); found {
+			pas = append(pas, n.p)
+		}
+		return false
+	})
+
+	page.SortByDefault(pas)
+
+	return pas
+}
+
 func (p *pageState) MarshalJSON() ([]byte, error) {
 	return page.MarshalPageToJSON(p)
 }
diff --git a/hugolib/site_benchmark_new_test.go b/hugolib/site_benchmark_new_test.go
index 4ffeaa8a1..1f16c97e5 100644
--- a/hugolib/site_benchmark_new_test.go
+++ b/hugolib/site_benchmark_new_test.go
@@ -378,14 +378,10 @@ contentDir="content/sv"
 		{"List terms", func(b testing.TB) *sitesBuilder {
 
 			pageTemplateTemplate := `
-{{ $taxo := "categories" }}
 <ul>
-    {{ range .Param $taxo }}
-        {{ $name := . }}
-        {{ with $.Site.GetPage (printf "/%s/%s" $taxo ($name | urlize)) }}
-            <li><a href="{{ .Permalink }}">{{ $name }}</a></li>
-        {{ end }}
-    {{ end }}
+    {{ range (.GetTerms "categories") }}
+        <li><a href="{{ .Permalink }}">{{ .LinkTitle }}</a></li>
+   {{ end }}
 </ul>
 `
 
diff --git a/hugolib/taxonomy_test.go b/hugolib/taxonomy_test.go
index d91e7699f..913773da6 100644
--- a/hugolib/taxonomy_test.go
+++ b/hugolib/taxonomy_test.go
@@ -542,25 +542,41 @@ func TestTaxonomiesPageCollections(t *testing.T) {
 	t.Parallel()
 
 	b := newTestSitesBuilder(t)
-	b.WithContent("p1.md", `---
+	b.WithContent(
+		"_index.md", `---
+title: "Home Sweet Home"
+categories: [ "dogs", "gorillas"]
+---
+`,
+		"section/_index.md", `---
+title: "Section"
+categories: [ "cats", "dogs", "birds"]
+---
+`,
+		"section/p1.md", `---
 title: "Page1"
 categories: ["funny", "cats"]
 ---
-`, "p2.md", `---
+`, "section/p2.md", `---
 title: "Page2"
 categories: ["funny"]
 ---
 `)
 
 	b.WithTemplatesAdded("index.html", `
+{{ $home := site.Home }}
+{{ $section := site.GetPage "section" }}
 {{ $categories := site.GetPage "categories" }}
 {{ $funny := site.GetPage "categories/funny" }}
 {{ $cats := site.GetPage "categories/cats" }}
+{{ $p1 := site.GetPage "section/p1" }}
 
 Categories Pages: {{ range $categories.Pages}}{{.RelPermalink }}|{{ end }}:END
 Funny Pages: {{ range $funny.Pages}}{{.RelPermalink }}|{{ end }}:END
 Cats Pages: {{ range $cats.Pages}}{{.RelPermalink }}|{{ end }}:END
-
+P1 Terms: {{ range $p1.GetTerms "categories" }}{{.RelPermalink }}|{{ end }}:END
+Section Terms: {{ range $section.GetTerms "categories" }}{{.RelPermalink }}|{{ end }}:END
+Home Terms: {{ range $home.GetTerms "categories" }}{{.RelPermalink }}|{{ end }}:END
 `)
 
 	b.Build(BuildCfg{})
@@ -575,12 +591,15 @@ Cats Pages: {{ range $cats.Pages}}{{.RelPermalink }}|{{ end }}:END
 	b.Assert(funny.Parent(), qt.Equals, cat)
 
 	b.AssertFileContent("public/index.html", `
-Categories Pages: /categories/cats/|/categories/funny/|:END
-Funny Pages: /p1/|/p2/|:END
-Cats Pages: /p1/|:END
+ Categories Pages: /categories/birds/|/categories/cats/|/categories/dogs/|/categories/funny/|/categories/gorillas/|:END
+ Funny Pages: /section/p1/|/section/p2/|:END
+ Cats Pages: /section/p1/|/section/|:END
+ P1 Terms: /categories/cats/|/categories/funny/|:END
+ Section Terms: /categories/birds/|/categories/cats/|/categories/dogs/|:END
+ Home Terms: /categories/dogs/|/categories/gorillas/|:END
 `)
 
-	b.AssertFileContent("public/categories/funny/index.xml", `<link>http://example.com/p1/</link>`)
+	b.AssertFileContent("public/categories/funny/index.xml", `<link>http://example.com/section/p1/</link>`)
 	b.AssertFileContent("public/categories/index.xml", `<link>http://example.com/categories/funny/</link>`)
 
 }
diff --git a/resources/page/page.go b/resources/page/page.go
index c096cb726..1225f43d0 100644
--- a/resources/page/page.go
+++ b/resources/page/page.go
@@ -252,6 +252,10 @@ type PageWithoutContent interface {
 	maps.Scratcher
 	RelatedKeywordsProvider
 
+	// GetTerms gets the terms of a given taxonomy,
+	// e.g. GetTerms("categories")
+	GetTerms(taxonomy string) Pages
+
 	DeprecatedWarningPageMethods
 }
 
diff --git a/resources/page/page_nop.go b/resources/page/page_nop.go
index 16663ab39..ccfbf525f 100644
--- a/resources/page/page_nop.go
+++ b/resources/page/page_nop.go
@@ -174,6 +174,10 @@ func (p *nopPage) GetParam(key string) interface{} {
 	return nil
 }
 
+func (p *nopPage) GetTerms(taxonomy string) Pages {
+	return nil
+}
+
 func (p *nopPage) GitInfo() *gitmap.GitInfo {
 	return nil
 }
diff --git a/resources/page/testhelpers_test.go b/resources/page/testhelpers_test.go
index dd28fa2cb..9c8605dad 100644
--- a/resources/page/testhelpers_test.go
+++ b/resources/page/testhelpers_test.go
@@ -222,6 +222,10 @@ func (p *testPage) GetParam(key string) interface{} {
 	panic("not implemented")
 }
 
+func (p *testPage) GetTerms(taxonomy string) Pages {
+	panic("not implemented")
+}
+
 func (p *testPage) GetRelatedDocsHandler() *RelatedDocsHandler {
 	return relatedDocsHandler
 }