Template

Rendering

In handler functions, we can use the context method Context#Render(code int, name string, data any) error to render our template files into HTML code and respond to the client. However, before doing so, we must register a template engine by setting the Slim instance property Slim#Renderer.

Slim allows us to use any template engine to implement template rendering functionality, as long as we implement the following interface:

Template engine interface

type Renderer interface {    Render(c slim.Context, w io.Writer, name string, data any) error}

The example below demonstrates how to implement a template engine using Go’s standard library html/template package:

Implement the interface slim.Renderer

Implement template engine

type Template struct {    templates *template.Template}func (t *Template) Render(c slim.Context, w io.Writer, name string, data any) error {    return t.templates.ExecuteTemplate(w, name, data)}

Pre-compile templates

views/hello.html

{{define "hello"}}Hello, {{.}}!{{end}}

Pre-compile templates

t := &Template{    templates: template.Must(template.ParseGlob("views/*.html")),}

 s := slim.New() s.Renderer = t s.GET("/hello", Hello)

Render template in handler

Render template

func Hello(c slim.Context) error {    return c.Render(http.StatusOK, "hello", "World")}

Enhancement

In some cases, it may be useful to generate URIs from templates. To do this, you need to call from the template itself. Golang’s standard library html/template is not well-suited for this task, but this can be accomplished in two ways: providing a common method on all objects passed to the template, or passing and enhancing this object in a custom renderer. Given the flexibility of the latter approach, here is an example program:

template.html

<html>  <body>    <h1>Hello {{index . "name"}}</h1>    <p>      {{ with $x := index . "reverse" }} {{ call $x "foobar" }} &lt;-- this will call the $x with parameter "foobar" {{      end }}    </p>  </body></html>

Our server code:

server.go

package mainimport (    "html/template"    "io"    "log"    "net/http"    "go-slim.dev/slim")// TemplateRenderer is a custom html/template renderer for Echo frameworktype TemplateRenderer struct {    templates *template.Template}// Render renders a template documentfunc (t *TemplateRenderer) Render(c slim.Context, w io.Writer, name string, data interface{}) error {    // Add global methods if data is a map    if viewContext, isMap := data.(map[string]interface{}); isMap {        viewContext["reverse"] = c.Slim().Reverse    }    return t.templates.ExecuteTemplate(w, name, data)}func main() {  s := slim.New()  renderer := &TemplateRenderer{      templates: template.Must(template.ParseGlob("*.html")),  }  s.Renderer = renderer  // Named route "foobar"  s.GET("/something", func(c slim.Context) error {      return c.Render(http.StatusOK, "template.html", map[string]any{          "name": "Dolly!",      })  }).Name = "foobar"  log.Fatal(s.Start(":8000"))}

Rendering

Enhancement

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