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Template

httpsrv provides view template rendering capabilities using Go's template engine. Templates are typically used in Web MVC's View (V) layer to render HTML pages.

Setting Up Template Path

Set template path when initializing Module:

func NewModule() *httpsrv.Module {
    mod := httpsrv.NewModule("ui")
    mod.SetTemplatePath("./views/ui")
    return mod
}

Basic Usage

Simple Template Rendering

type User struct {
    *httpsrv.Controller
}

func (c User) ProfileAction() {
    user := map[string]interface{}{
        "name": "John Doe",
        "email": "john@example.com",
    }
    
    c.Data["user"] = user
    c.Render("user/profile.tpl")
}

Template file user/profile.tpl:

<!DOCTYPE html>
<html>
<head>
    <title>User Profile</title>
</head>
<body>
    <h1>{{.user.name}}</h1>
    <p>Email: {{.user.email}}</p>
</body>
</html>

Rendering with Specific Module

// Render template from specific module
c.Render("user", "profile.tpl")

Template Syntax

Variables

{{.variable}}
{{.user.name}}
{{index .users 0}}

Conditional Statements

{{if .user.is_admin}}
    <p>Admin User</p>
{{else}}
    <p>Regular User</p>
{{end}}

Loops

{{range .users}}
    <div>{{.name}}</div>
{{end}}

With Context

{{with .user}}
    <p>{{.name}} - {{.email}}</p>
{{end}}

Template Inheritance

Base Template

<!-- layouts/base.tpl -->
<!DOCTYPE html>
<html>
<head>
    <title>{{block "title" .}}Default Title{{end}}</title>
</head>
<body>
    <header>{{block "header" .}}Default Header{{end}}</header>
    <main>
        {{block "content" .}}{{end}}
    </main>
    <footer>{{block "footer" .}}Default Footer{{end}}</footer>
</body>
</html>

Child Template

<!-- user/profile.tpl -->
{{template "layouts/base.tpl" .}}

{{define "title"}}User Profile{{end}}

{{define "header"}}
    <nav>My App Navigation</nav>
{{end}}

{{define "content"}}
    <h1>{{.user.name}}</h1>
    <p>{{.user.email}}</p>
{{end}}

Built-in Functions

String Functions

{{.name | upper}}      <!-- Uppercase -->
{{.name | lower}}      <!-- Lowercase -->
{{.name | trim}}       <!-- Trim whitespace -->
{{.name | htmlEscape}} <!-- HTML escape -->

Number Functions

{{.price | format "%.2f"}} <!-- Format number -->
{{.count | add 10}}       <!-- Add -->
{{.count | sub 5}}        <!-- Subtract -->

Date Functions

{{.created_at | date "2006-01-02"}}
{{.updated_at | datetime}}

Array Functions

{{len .items}}         <!-- Length -->
{{index .items 0}}      <!-- Get by index -->

Custom Functions

Register custom template functions:

func init() {
    httpsrv.GlobalService.Config.RegisterTemplateFunc("truncate", Truncate)
}

func Truncate(s string, length int) string {
    if len(s) <= length {
        return s
    }
    return s[:length] + "..."
}

Use in template:

{{.description | truncate 100}}

Practical Examples

User List

type User struct {
    *httpsrv.Controller
}

func (c User) ListAction() {
    users := []map[string]interface{}{
        {"id": 1, "name": "Alice", "email": "alice@example.com"},
        {"id": 2, "name": "Bob", "email": "bob@example.com"},
    }
    
    c.Data["users"] = users
    c.Data["title"] = "User List"
    c.Render("user/list.tpl")
}

Template:

{{template "layouts/base.tpl" .}}

{{define "title"}}{{.title}}{{end}}

{{define "content"}}
    <table>
        <thead>
            <tr>
                <th>ID</th>
                <th>Name</th>
                <th>Email</th>
            </tr>
        </thead>
        <tbody>
            {{range .users}}
            <tr>
                <td>{{.id}}</td>
                <td>{{.name}}</td>
                <td>{{.email}}</td>
            </tr>
            {{end}}
        </tbody>
    </table>
{{end}}

Form with Errors

func (c User) CreateAction() {
    if c.Request.Method == "GET" {
        c.Render("user/form.tpl")
        return
    }
    
    name := c.Params.Value("name")
    if name == "" {
        c.Data["error"] = "Name is required"
        c.Data["name"] = ""
        c.Render("user/form.tpl")
        return
    }
    
    // Create user...
}

Template:

<form method="POST" action="/user/create">
    {{if .error}}
        <div class="error">{{.error}}</div>
    {{end}}
    
    <div>
        <label>Name:</label>
        <input type="text" name="name" value="{{.name}}">
    </div>
    
    <button type="submit">Submit</button>
</form>

Auto Render

When c.AutoRender is true (default), system automatically searches for template:

type User struct {
    *httpsrv.Controller
}

// System will look for: user/index.tpl
func (c User) IndexAction() {
    c.Data["users"] = getUsers()
    // No need to call c.Render()
}

// System will look for: user/profile.tpl
func (c User) ProfileAction() {
    c.Data["user"] = getUser()
    // No need to call c.Render()
}

Template Path Rules

For Controller named User with Action ProfileAction:

  1. If c.Render("user/profile.tpl") → Look for user/profile.tpl in all template paths
  2. If c.Render("user", "profile.tpl") → Look for user/profile.tpl in all template paths
  3. If AutoRender → Look for user/profile.tpl in all template paths

Template search order:

  • First template path set in Module
  • Second template path set in Module
  • ...

Notes

  1. Template files use .tpl extension by default
  2. Template variables are passed through c.Data map
  3. Use {{block}} for template inheritance
  4. Use {{define}} to define reusable template blocks
  5. All built-in Go template functions are available