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Template Engine

Previously, we mentioned several methods for returning template content as follows:

func (r *Response) WriteTpl(tpl string, params ...gview.Params) error 
func (r *Response) WriteTplDefault(params ...gview.Params) error 
func (r *Response) WriteTplContent(content string, params ...gview.Params) error

By default, the template directory is resource/template.

  • WriteTpl parses and returns the content of the template file located relative to resource/template.
  • WriteTplDefault parses and returns the default template located at resource/template/index.html.
  • WriteTplContent parses and returns the template string.

The commonly used method is WriteTpl, while the other two methods are for simple understanding.

func (c *Controller) Tpl(req *ghttp.Request) {
    req.Response.WriteTplDefault() // Parses and returns the default template file content
    // Parses and returns the template string
    req.Response.WriteTplContent("<h1>Hello, {{.name}} welcome to learn {{.lang}}</h1>", g.Map{"name": "Wang Daochang", "lang": "GoFrame"})
}

Simple Usage Example​

resource/template/hello/index.html

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>

    <div>
        <h1>Hello, {{.name}}</h1>
        <h2>Welcome to the {{.lesson}} course</h2>
        <p>This course has {{.num}} lessons. Currently learning {{.what}}</p>
    </div>

</body>
</html>

controller

func (c *Controller) Tpl(req *ghttp.Request) {
    data := g.Map{
        "name":   "Wang Yaodao",
        "lesson": "Introduction to GoFrame",
        "num":    5,
        "what":   "Template engine usage example",
    }

    req.Response.WriteTpl("hello/index.html", data)
}

Template Configuration​

In general, the default configuration is sufficient for template usage. If modifications are needed, they can be made in manifest/config/config.yaml.

viewer: # Template configuration
  paths: ["resource/template", "/www/template"] # Template path configuration, can configure multiple paths
  defaultFile: "index.hmtl" # File parsed by WriteTplDefault
  delimiters: ["${", "}"] # Template engine variable delimiters, default is ["{{", "}}"]

Static Resources​

Static resources are not part of the template engine content, but they are often needed in template files. Therefore, here is some additional information.

Static resources typically refer to JS/CSS/image files or static HTML files. In GoFrame projects, these files are placed in resource/public. To reference these resources in template files, you need to enable static resource serving. There are two ways to do this:

  • Configuration file

manifest/config/config.yaml

server:
  serverRoot:  "resource/public"
  indexFolder: true # This can be omitted, here for understanding
  • Enable via code

internal/cmd/cmd.go

s := g.Server()
s.SetServerRoot("resource/public")
s.SetIndexFolder(true)

The serverRoot configures the root directory for static resources (resource/public). Resource URLs are relative to resource/public.

For example, if resource/public/resource/css/bootstrap.css contains a file, it is referenced as follows:

<link rel="stylesheet" href="/resource/css/bootstrap.css">

Conditional Statements​

Conditional statements can be used in templates to display different content based on whether conditions are met. The syntax is as follows:

{{if .condition}}
Display content when condition is true
{{else}}
Display content when condition is false
{{end}}

You can nest and chain multiple {{else if .condition}} statements. The condition is false if .condition is empty (0, "", nil, etc.), otherwise true.

Example:

resource/template/hello/index.html

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="/resource/css/bootstrap.css">
    <title>Document</title>
</head>
<body>

   {{if .name}}
   <h1>Value of name: {{.name}}</h1>
   {{else}}
   <h1>Value of name is false/""/0/nil, etc.</h1>
   {{end}}

</body>
</html>

controller

func (c *Controller) Tpl(req *ghttp.Request) {
    data := g.Map{
        "name":   "Wang Yaodao",
        "lesson": "Introduction to GoFrame",
        "num":    5,
        "what":   "Template engine usage example",
    }

    req.Response.WriteTpl("hello/index.html", data)
}

Comparison Operators

Direct use of >, <, ==, etc., for comparison is not supported in templates. Instead, use conditional functions:

FunctionEquivalent
eq==
ne!=
lt<
le<=
gt>
ge>=

Usage example:

{{if eq 5 .num}}
<h1>num == 5</h1>
{{else if lt 5 .num}}
<h1>num > 5</h1>
{{else}}
<h1>num < 5</h1>
{{end}}

There are additional uses for these functions, but we cover the basics here.

Logical Operators

Logical operators and, or, not can be used for logical operations in templates:

{{if and (gt .num 0) (lt .num 5)}}    if num > 0 && num < 5
{{if or (eq .num 0) (eq .num 5)}}    if num == 0 || num == 5
{{if not (eq .num 0)}}    if num != 0

Loops​

range ... end

Looping through slices

controller/hello.go

data := g.Map{
    "slice": g.Array{1, 2, 3, "Zhang Chulan", "Zhuge Qing"},
}

req.Response.WriteTpl("hello/index.html", data)

index.html

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="/resource/css/bootstrap.css">
    <title>Document</title>
</head>
<body>

   {{range .slice}}
   <span>{{.}}</span> 
   {{end}}

   {{range $index, $value := .slice}}
   <p>index = {{$index}}, value = {{$value}}</p>
   {{end}}


</body>
</html>

Using map data

controller/hello.go

func (c *Controller) Tpl(req *ghttp.Request) {
    data := g.Map{
        "mp": g.Map{
            "name":   "Feng Baobao",
            "gender": "Female",
            "age":    100,
            "hobby":  "Burying people",
        },
    }

    req.Response.WriteTpl("hello/index.html", data)
}

index.html

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="/resource/css/bootstrap.css">
    <title>Document</title>
</head>
<body>

   <div class="container">
    <p>Name: {{.mp.name}}</p>
    <p>Gender: {{.mp.gender}}</p>
    <p>Age: {{.mp.age}}</p>
    <p>Hobby: {{.mp.hobby}}</p>


    {{range .mp}}
    <p>{{.}}</p>
    {{end}}

    {{range $key, $value := .mp}}
    <p>{{$key}}: {{$value}}</p>
    {{end}}

    </div>


</body>
</html>