Backport Iif (#31353)

2 files changed, 70 insertions, 2 deletions

diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index 94464fe628..330cbf8908 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -9,6 +9,7 @@ import (
 	"html"
 	"html/template"
 	"net/url"
+	"reflect"
 	"slices"
 	"strings"
 	"time"
@@ -237,8 +238,8 @@ func DotEscape(raw string) string {
 
 // Iif is an "inline-if", similar util.Iif[T] but templates need the non-generic version,
 // and it could be simply used as "{{Iif expr trueVal}}" (omit the falseVal).
-func Iif(condition bool, vals ...any) any {
-	if condition {
+func Iif(condition any, vals ...any) any {
+	if isTemplateTruthy(condition) {
 		return vals[0]
 	} else if len(vals) > 1 {
 		return vals[1]
@@ -246,6 +247,32 @@ func Iif(condition bool, vals ...any) any {
 	return nil
 }
 
+func isTemplateTruthy(v any) bool {
+	if v == nil {
+		return false
+	}
+
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Bool:
+		return rv.Bool()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return rv.Int() != 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return rv.Uint() != 0
+	case reflect.Float32, reflect.Float64:
+		return rv.Float() != 0
+	case reflect.Complex64, reflect.Complex128:
+		return rv.Complex() != 0
+	case reflect.String, reflect.Slice, reflect.Array, reflect.Map:
+		return rv.Len() > 0
+	case reflect.Struct:
+		return true
+	default:
+		return !rv.IsNil()
+	}
+}
+
 // Eval the expression and return the result, see the comment of eval.Expr for details.
 // To use this helper function in templates, pass each token as a separate parameter.
 //
diff --git a/modules/templates/helper_test.go b/modules/templates/helper_test.go
index 0cefb7a6b2..ea5da7be80 100644
--- a/modules/templates/helper_test.go
+++ b/modules/templates/helper_test.go
@@ -5,8 +5,11 @@ package templates
 
 import (
 	"html/template"
+	"strings"
 	"testing"
 
+	"code.gitea.io/gitea/modules/util"
+
 	"github.com/stretchr/testify/assert"
 )
 
@@ -65,3 +68,41 @@ func TestHTMLFormat(t *testing.T) {
 func TestSanitizeHTML(t *testing.T) {
 	assert.Equal(t, template.HTML(`<a href="/" rel="nofollow">link</a> xss <div>inline</div>`), SanitizeHTML(`<a href="/">link</a> <a href="javascript:">xss</a> <div style="dangerous">inline</div>`))
 }
+
+func TestTemplateTruthy(t *testing.T) {
+	tmpl := template.New("test")
+	tmpl.Funcs(template.FuncMap{"Iif": Iif})
+	template.Must(tmpl.Parse(`{{if .Value}}true{{else}}false{{end}}:{{Iif .Value "true" "false"}}`))
+
+	cases := []any{
+		nil, false, true, "", "string", 0, 1,
+		byte(0), byte(1), int64(0), int64(1), float64(0), float64(1),
+		complex(0, 0), complex(1, 0),
+		(chan int)(nil), make(chan int),
+		(func())(nil), func() {},
+		util.ToPointer(0), util.ToPointer(util.ToPointer(0)),
+		util.ToPointer(1), util.ToPointer(util.ToPointer(1)),
+		[0]int{},
+		[1]int{0},
+		[]int(nil),
+		[]int{},
+		[]int{0},
+		map[any]any(nil),
+		map[any]any{},
+		map[any]any{"k": "v"},
+		(*struct{})(nil),
+		struct{}{},
+		util.ToPointer(struct{}{}),
+	}
+	w := &strings.Builder{}
+	truthyCount := 0
+	for i, v := range cases {
+		w.Reset()
+		assert.NoError(t, tmpl.Execute(w, struct{ Value any }{v}), "case %d (%T) %#v fails", i, v, v)
+		out := w.String()
+		truthyCount += util.Iif(out == "true:true", 1, 0)
+		truthyMatches := out == "true:true" || out == "false:false"
+		assert.True(t, truthyMatches, "case %d (%T) %#v fail: %s", i, v, v, out)
+	}
+	assert.True(t, truthyCount != 0 && truthyCount != len(cases))
+}