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package util
import (
"errors"
"fmt"
"strings"
"github.com/flosch/pongo2"
)
// RenderTemplate renders a pongo2 template with nesting support.
// This supports up to 3 levels of nesting (to avoid loops).
func RenderTemplate(template string, ctx pongo2.Context) (string, error) {
// Prepare a custom set.
custom := pongo2.NewSet("render-template", pongo2.DefaultLoader)
// Block the use of some tags.
for _, tag := range []string{"extends", "import", "include", "ssi"} {
err := custom.BanTag(tag)
if err != nil {
return "", fmt.Errorf("Failed to configure custom pongo2 parser: Failed to block tag tag %q: %w", tag, err)
}
}
// Limit recursion to 3 levels.
for range 3 {
// Load template from string
tpl, err := custom.FromString("{% autoescape off %}" + template + "{% endautoescape %}")
if err != nil {
return "", err
}
// Get rendered template
ret, err := tpl.Execute(ctx)
if err != nil {
return ret, err
}
// Check if another pass is needed.
if !strings.Contains(ret, "{{") && !strings.Contains(ret, "{%") {
return ret, nil
}
// Prepare for another run.
template = ret
}
return "", errors.New("Maximum template recursion limit reached")
}
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