hugolib: Consider summary in front matter for .Summary

Add the ability to have a `summary` page variable that overrides
the auto-generated summary.  Logic for obtaining summary becomes:

  * if summary divider is present in content, use the text above it
  * if summary variables is present in page metadata, use that
  * auto-generate summary from first _x_ words of the content

Fixes #5800

5 files changed, 70 insertions, 1 deletions

diff --git a/hugolib/page__meta.go b/hugolib/page__meta.go
index 1e013db66..eefecbe4a 100644
--- a/hugolib/page__meta.go
+++ b/hugolib/page__meta.go
@@ -64,6 +64,8 @@ type pageMeta struct {
 	title     string
 	linkTitle string
 
+	summary string
+
 	resourcePath string
 
 	weight int
@@ -361,6 +363,9 @@ func (pm *pageMeta) setMetadata(p *pageState, frontmatter map[string]interface{}
 		case "linktitle":
 			pm.linkTitle = cast.ToString(v)
 			pm.params[loki] = pm.linkTitle
+		case "summary":
+			pm.summary = cast.ToString(v)
+			pm.params[loki] = pm.summary
 		case "description":
 			pm.description = cast.ToString(v)
 			pm.params[loki] = pm.description
diff --git a/hugolib/page__per_output.go b/hugolib/page__per_output.go
index 05b35cc87..177e0420a 100644
--- a/hugolib/page__per_output.go
+++ b/hugolib/page__per_output.go
@@ -128,6 +128,14 @@ func newPageContentOutput(p *pageState) func(f output.Format) (*pageContentOutpu
 							cp.summary = helpers.BytesToHTML(summary)
 						}
 					}
+				} else if cp.p.m.summary != "" {
+					html := cp.p.s.ContentSpec.RenderBytes(&helpers.RenderingContext{
+						Content: []byte(cp.p.m.summary), RenderTOC: false, PageFmt: cp.p.m.markup,
+						Cfg:        p.Language(),
+						DocumentID: p.File().UniqueID(), DocumentName: p.File().Path(),
+						Config: cp.p.getRenderingConfig()})
+					html = cp.p.s.ContentSpec.TrimShortHTML(html)
+					cp.summary = helpers.BytesToHTML(html)
 				}
 			}
 
@@ -271,7 +279,7 @@ func (p *pageContentOutput) WordCount() int {
 }
 
 func (p *pageContentOutput) setAutoSummary() error {
-	if p.p.source.hasSummaryDivider {
+	if p.p.source.hasSummaryDivider || p.p.m.summary != "" {
 		return nil
 	}
 
diff --git a/hugolib/page_test.go b/hugolib/page_test.go
index 6d9d337eb..a3b86ef2a 100644
--- a/hugolib/page_test.go
+++ b/hugolib/page_test.go
@@ -45,6 +45,16 @@ const (
 
 	simplePageRFC3339Date = "---\ntitle: RFC3339 Date\ndate: \"2013-05-17T16:59:30Z\"\n---\nrfc3339 content"
 
+	simplePageWithoutSummaryDelimiter = `---
+title: SimpleWithoutSummaryDelimiter
+---
+[Lorem ipsum](https://lipsum.com/) dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
+
+Additional text.
+
+Further text.
+`
+
 	simplePageWithSummaryDelimiter = `---
 title: Simple
 ---
@@ -54,6 +64,16 @@ Summary Next Line
 Some more text
 `
 
+	simplePageWithSummaryParameter = `---
+title: SimpleWithSummaryParameter
+summary: "Page with summary parameter and [a link](http://www.example.com/)"
+---
+
+Some text.
+
+Some more text.
+`
+
 	simplePageWithSummaryDelimiterAndMarkdownThatCrossesBorder = `---
 title: Simple
 ---
@@ -519,6 +539,22 @@ func TestCreateNewPage(t *testing.T) {
 	testAllMarkdownEnginesForPages(t, assertFunc, settings, simplePage)
 }
 
+func TestPageSummary(t *testing.T) {
+	t.Parallel()
+	assertFunc := func(t *testing.T, ext string, pages page.Pages) {
+		p := pages[0]
+		checkPageTitle(t, p, "SimpleWithoutSummaryDelimiter")
+		// Source is not Asciidoctor- or RST-compatibile so don't test them
+		if ext != "ad" && ext != "rst" {
+			checkPageContent(t, p, normalizeExpected(ext, "<p><a href=\"https://lipsum.com/\">Lorem ipsum</a> dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>\n\n<p>Additional text.</p>\n\n<p>Further text.</p>\n"), ext)
+			checkPageSummary(t, p, normalizeExpected(ext, "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Additional text."), ext)
+		}
+		checkPageType(t, p, "page")
+	}
+
+	testAllMarkdownEnginesForPages(t, assertFunc, nil, simplePageWithoutSummaryDelimiter)
+}
+
 func TestPageWithDelimiter(t *testing.T) {
 	t.Parallel()
 	assertFunc := func(t *testing.T, ext string, pages page.Pages) {
@@ -532,6 +568,22 @@ func TestPageWithDelimiter(t *testing.T) {
 	testAllMarkdownEnginesForPages(t, assertFunc, nil, simplePageWithSummaryDelimiter)
 }
 
+func TestPageWithSummaryParameter(t *testing.T) {
+	t.Parallel()
+	assertFunc := func(t *testing.T, ext string, pages page.Pages) {
+		p := pages[0]
+		checkPageTitle(t, p, "SimpleWithSummaryParameter")
+		checkPageContent(t, p, normalizeExpected(ext, "<p>Some text.</p>\n\n<p>Some more text.</p>\n"), ext)
+		// Summary is not Asciidoctor- or RST-compatibile so don't test them
+		if ext != "ad" && ext != "rst" {
+			checkPageSummary(t, p, normalizeExpected(ext, "Page with summary parameter and <a href=\"http://www.example.com/\">a link</a>"), ext)
+		}
+		checkPageType(t, p, "page")
+	}
+
+	testAllMarkdownEnginesForPages(t, assertFunc, nil, simplePageWithSummaryParameter)
+}
+
 // Issue #3854
 // Also see https://github.com/gohugoio/hugo/issues/3977
 func TestPageWithDateFields(t *testing.T) {
diff --git a/hugolib/rss_test.go b/hugolib/rss_test.go
index 683a737c5..38f0f1eff 100644
--- a/hugolib/rss_test.go
+++ b/hugolib/rss_test.go
@@ -55,6 +55,9 @@ func TestRSSOutput(t *testing.T) {
 	if c != rssLimit {
 		t.Errorf("incorrect RSS item count: expected %d, got %d", rssLimit, c)
 	}
+
+	// Encoded summary
+	th.assertFileContent(filepath.Join("public", rssURI), "<?xml", "description", "A &lt;em&gt;custom&lt;/em&gt; summary")
 }
 
 // Before Hugo 0.49 we set the pseudo page kind RSS on the page when output to RSS.
diff --git a/hugolib/site_test.go b/hugolib/site_test.go
index 21575072d..5912abbc9 100644
--- a/hugolib/site_test.go
+++ b/hugolib/site_test.go
@@ -586,6 +586,7 @@ date = "2012-01-01"
 publishdate = "2012-01-01"
 my_param = "baz"
 my_date = 2010-05-27T07:32:00Z
+summary = "A _custom_ summary"
 categories = [ "hugo" ]
 +++
 Front Matter with Ordered Pages 4. This is longer content`