Templates

Template Rendering

Context#Render(code int, name string, data interface{}) error renders a template
with data and sends a text/html response with status code. Templates can be registered by setting Echo.Renderer, allowing us to use any template engine.

Example below shows how to use Go html/template:

  1. Implement echo.Renderer interface

    1.  type Template struct {
    2.      templates *template.Template
    3.  }
    5.  func (t *Template) Render(w io.Writer, name string, data interface{}, c echo.Context) error {
    6.      return t.templates.ExecuteTemplate(w, name, data)
    7.  }

  2. Pre-compile templates

    public/views/hello.html

    1.  {{define "hello"}}Hello, {{.}}!{{end}}
    1.  t := &Template{
    2.      templates: template.Must(template.ParseGlob("public/views/*.html")),
    3.  }

  3. Register templates

    1.  e := echo.New()
    2.  e.Renderer = t
    3.  e.GET("/hello", Hello)

  4. Render a template inside your handler

    1.  func Hello(c echo.Context) error {
    2.      return c.Render(http.StatusOK, "hello", "World")
    3.  }

Advanced - Calling Echo from templates

In certain situations it might be useful to generate URIs from the templates. In order to do so, you need to call Echo#Reverse from the templates itself. Golang’s html/template package is not the best suited for this job, but this can be done in two ways: by providing a common method on all objects passed to templates or by passing map[string]interface{} and augmenting this object in the custom renderer. Given the flexibility of the latter approach, here is a sample program:

template.html

  1. <html>
  2.     <body>
  3.         <h1>Hello {{index . "name"}}</h1>
  5.         <p>{{ with $x := index . "reverse" }}
  6.            {{ call $x "foobar" }} &lt;-- this will call the $x with parameter "foobar"
  7.            {{ end }}
  8.         </p>
  9.     </body>
  10. </html>

server.go

  1. package main
  3. import (
  4.     "html/template"
  5.     "io"
  6.     "log"
  7.     "net/http"
  9.     "github.com/labstack/echo"
  10. )
  12. // TemplateRenderer is a custom html/template renderer for Echo framework
  13. type TemplateRenderer struct {
  14.     templates *template.Template
  15. }
  17. // Render renders a template document
  18. func (t *TemplateRenderer) Render(w io.Writer, name string, data interface{}, c echo.Context) error {
  20.     // Add global methods if data is a map
  21.     if viewContext, isMap := data.(map[string]interface{}); isMap {
  22.         viewContext["reverse"] = c.Echo().Reverse
  23.     }
  25.     return t.templates.ExecuteTemplate(w, name, data)
  26. }
  28. func main() {
  29.   e := echo.New()
  30.   renderer := &TemplateRenderer{
  31.       templates: template.Must(template.ParseGlob("*.html")),
  32.   }
  33.   e.Renderer = renderer
  35.   // Named route "foobar"
  36.   e.GET("/something", func(c echo.Context) error {
  37.       return c.Render(http.StatusOK, "something.html", map[string]interface{}{
  38.           "name": "Dolly!",
  39.       })
  40.   }).Name = "foobar"
  42.   log.Fatal(e.Start(":8000"))
  43. }