Add templating functions for working with URLs (#4625)

* Add safeUrl to mark URL strings as safe

Signed-off-by: Ruben Simons <[email protected]>

* Add urlUnescape to allow for reversing of escaped URL strings

Signed-off-by: Ruben Simons <[email protected]>

---------

Signed-off-by: Ruben Simons <[email protected]>
Co-authored-by: Ben Kochie <[email protected]>

Author: StopMotionCuber

docs/notifications.md

@@ -93,6 +93,8 @@ templating.
 | reReplaceAll | pattern, replacement, text | [Regexp.ReplaceAllString](http://golang.org/pkg/regexp/#Regexp.ReplaceAllString) Regexp substitution, unanchored. |
 | join | sep string, s []string | [strings.Join](http://golang.org/pkg/strings/#Join), concatenates the elements of s to create a single string. The separator string sep is placed between elements in the resulting string. (note: argument order inverted for easier pipelining in templates.) |
 | safeHtml | text string | [html/template.HTML](https://golang.org/pkg/html/template/#HTML), Marks string as HTML not requiring auto-escaping. |
+| safeUrl | text string | [html/template.URL](https://golang.org/pkg/html/template/#URL), Marks string as URL not requiring auto-escaping. |
+| urlUnescape | text string | [url.QueryUnescape](https://pkg.go.dev/net/url#QueryUnescape), unescapes a URL with % encoding |
 | stringSlice | ...string | Returns the passed strings as a slice of strings. |
 | date | string, time.Time | Returns the text representation of the time in the specified format. For documentation on formats refer to [pkg.go.dev/time](https://pkg.go.dev/time#pkg-constants). |
 | tz | string, time.Time | Returns the time in the timezone. For example, Europe/Paris. |

template/template.go

@@ -188,6 +188,10 @@ var DefaultFuncs = FuncMap{
 	"safeHtml": func(text string) tmplhtml.HTML {
 		return tmplhtml.HTML(text)
 	},
+	"safeUrl": func(text string) tmplhtml.URL {
+		return tmplhtml.URL(text)
+	},
+	"urlUnescape": url.QueryUnescape,
 	"reReplaceAll": func(pattern, repl, text string) string {
 		re := regexp.MustCompile(pattern)
 		return re.ReplaceAllString(text, repl)

template/template_test.go

@@ -367,11 +367,28 @@ func TestTemplateExpansion(t *testing.T) {
 			html:  true,
 			exp:   "<b>",
 		},
+		{
+			title: "URL template with escaping",
+			in:    `<a href="/search?{{ "q=test%20foo" }}"></a>`,
+			html:  true,
+			exp:   `<a href="/search?q%3dtest%2520foo"></a>`,
+		},
+		{
+			title: "URL template using safeUrl",
+			in:    `<a href="/search?{{ "q=test%20foo" | safeUrl }}"></a>`,
+			html:  true,
+			exp:   `<a href="/search?q=test%20foo"></a>`,
+		},
 		{
 			title: "Template using reReplaceAll",
 			in:    `{{ reReplaceAll "ab" "AB" "abcdabcda"}}`,
 			exp:   "ABcdABcda",
 		},
+		{
+			title: "Template using urlUnescape",
+			in:    `{{ "search?q=test%20foo" | urlUnescape }}`,
+			exp:   "search?q=test foo",
+		},
 		{
 			title: "Template using stringSlice",
 			in:    `{{ with .GroupLabels }}{{ with .Remove (stringSlice "key1" "key3") }}{{ .SortedPairs.Values }}{{ end }}{{ end }}`,