Golang template usage tips guide: from beginner to advanced template development

Golang Template Development Guide: Tips for using templates from entry to mastery

Introduction:
In Golang, templates are a very convenient way to deal with data and generate text output. The Golang standard library provides two packages, html/template and text/template, for processing HTML and plain text templates. This article will introduce the usage skills of Golang templates from beginner to master, and provide specific code examples.

1. Template Basics
1.1 Template Creation
First, we need to create a template file, usually with .tmpl or .tpl as the suffix, such as hello.tmpl. In template files, we can use some specific syntax to mark and process templates.

1.2 Comments and whitespace
In template files, we can use comments to provide additional explanations and instructions. Comments are surrounded by {{/ and /}}, and the content in between will be ignored.

In templates, whitespace characters (spaces, tabs, newlines, etc.) are usually ignored. If you need to preserve whitespace characters in your template, you can use the whitespace-preserving tags {{- and -}}, for example {{- "Hello, World!" -}}.

1.3 Variables and functions
In templates, we can define and use variables. Variables are surrounded by {{ and }}. For example, {{.Title}} represents the value of the variable Title.

Template also supports function calling. Functions are surrounded by {{ and }}, followed by the function name. For example, {{len .Title}} means calling the len function to get the length of the Title variable.

2. Execution of templates
2.1 Parsing templates
In Golang, we need to use the Parse function of the template engine to parse the template file. The Parse function receives a file name as a parameter and returns a template object. The sample code is as follows:

package main

import (
    "html/template"
    "log"
)

func main() {
    // 解析模板
    tmpl, err := template.ParseFiles("hello.tmpl")
    if err != nil {
        log.Fatal(err)
    }

    // 执行模板
    err = tmpl.Execute(w, nil)
    if err != nil {
        log.Fatal(err)
    }
}

2.2 Execute the template
After parsing the template, we can use the Execute function to execute the template and output the results to the specified place. The Execute function accepts two parameters: a parameter of type io.Writer and a parameter to receive data. The sample code is as follows:

package main

import (
    "html/template"
    "log"
    "os"
)

func main() {
    // 解析模板
    tmpl, err := template.ParseFiles("hello.tmpl")
    if err != nil {
        log.Fatal(err)
    }

    // 执行模板
    err = tmpl.Execute(os.Stdout, nil)
    if err != nil {
        log.Fatal(err)
    }
}

3. Template data binding and control flow
3.1 Data binding
When executing the template, we can pass in some data to bind the variables in the template Certainly. These data can be of any type, such as strings, integers, structures, etc. The sample code is as follows:

package main

import (
    "html/template"
    "log"
    "os"
)

type Person struct {
    Name string
    Age  int
}

func main() {
    // 解析模板
    tmpl, err := template.ParseFiles("hello.tmpl")
    if err != nil {
        log.Fatal(err)
    }

    // 数据绑定
    data := Person{
        Name: "John",
        Age:  30,
    }

    // 执行模板
    err = tmpl.Execute(os.Stdout, data)
    if err != nil {
        log.Fatal(err)
    }
}

In the template file, we can use the period (.) to represent the current data context. For example {{.Name}} represents the Name field in the current data context.

3.2 Control flow
The template also supports some control flow statements, such as conditional judgments and loops. The if statement is used for conditional judgment and the range statement is used for looping. The sample code is as follows:

{{if .IsAdult}}
<p>Adult</p>
{{else}}
<p>Not adult</p>
{{end}}

{{range .Friends}}
<p>{{.Name}}</p>
{{end}}

4. Nesting and sharing of templates
4.1 Nesting of templates
In a template, we can use the {{template}} statement to reference other templates. This enables template nesting and code reuse. The sample code is as follows:

{{template "header"}}
<p>Page content</p>
{{template "footer"}}

4.2 Template Sharing
In order to facilitate the sharing of templates, we can define related templates in a file and use the {{define}} statement to define the template. The sample code is as follows:

{{define "header"}}
<p>Header content</p>
{{end}}

{{define "footer"}}
<p>Footer content</p>
{{end}}

5. Template security and performance optimization
5.1 Template security
When processing templates, we need to pay attention to the security of the template. In order to prevent XSS attacks, we can use the related functions provided by the html/template package to escape variables. The sample code is as follows:

{{.Title | html}}

5.2 Template performance optimization
In order to improve the performance of the template, we can cache the parsing results of the template. The sample code is as follows:

package main

import (
    "html/template"
    "log"
    "os"
)

var templates *template.Template

func init() {
    // 解析模板
    var err error
    templates, err = template.ParseGlob("*.tmpl")
    if err != nil {
        log.Fatal(err)
    }
}

func main() {
    // 执行模板
    err := templates.ExecuteTemplate(os.Stdout, "hello.tmpl", nil)
    if err != nil {
        log.Fatal(err)
    }
}

6. Summary
This article introduces the basic knowledge and usage skills of Golang templates, including template creation, parsing and execution, data binding and control flow, template nesting and sharing, as well as template security and performance optimization. Through learning and practice, we can better use templates to process data and generate text output, improving development efficiency and code quality. I hope this article is helpful to you, thank you for reading!

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