Template Data And Helpers

Set template data

Controllers pass data to templates with Set:

func (c *PostsController) Show(
    _ http.ResponseWriter,
    r *http.Request,
) error {
    post, ok := c.posts.Get(r.PathValue("post_id"))
    if !ok {
        return lazycontroller.Error(http.StatusNotFound, fmt.Errorf("post not found"))
    }

    c.Set("title", post.Title)
    c.Set("post", post)
    return nil
}

The view reads those values by name:

<h1>{{.title}}</h1>
<article>{{.post.Body}}</article>

Use built-in helpers

lazyapp registers route, asset, form, and Turbo helpers:

<a href="{{path_for "posts"}}">Posts</a>
{{stylesheet "/styles.css"}}
{{importmap "/assets/importmap.json"}}

Helpers return ordinary strings or trusted fragments, depending on what the helper renders.

Register app helpers

Application helpers are passed to lazyapp.New:

func RegisterHelpers() map[string]any {
    return map[string]any{
        "read_time": ReadTime,
    }
}

Wire them during startup:

func App() *lazyapp.App {
    return lazyapp.New(lazyapp.Config{
        Name:    "sample_app",
        Drawer:  Draw,
        Public:  app.Public,
        Views:   app.Views,
        Context: Context,
        Helpers: lazyapp.Helpers{helpers.RegisterHelpers()},
    })
}

Then call the helper from a template:

<p>{{read_time .post.Body}} min read</p>