Golang and Template package: Build reusable HTML templates

Whether you are developing web applications, building websites or generating HTML reports, HTML templates are an indispensable part. Using templates allows you to dynamically insert data into predefined HTML structures, allowing us to easily create reusable page layouts and content.

In the Go language, the built-in html/template package provides a powerful and easy-to-use template engine. It supports template nesting, conditional judgment, loop iteration and other functions, allowing us to flexibly build complex HTML templates.

First, we need to import the html/template package:

import (
    "html/template"
    "os"
)

Then, we create a template object and can define some custom functions as needed:

t := template.New("example")

// 定義一個(gè)自定義的函數(shù)
t = t.Funcs(template.FuncMap{
    "formatDate": func(date time.Time) string {
        return date.Format("2006-01-02")
    },
})

In this example, we define a custom function named formatDate to format a date of type time.Time to "2006-01 -02" in string form.

Next, we can use the ParseFiles function to parse the template file:

t, err := t.ParseFiles("template.html")
if err != nil {
    log.Fatal(err)
}

Template file template.html can contain some placeholders, using For dynamically inserting data into HTML structures. For example, we can define a placeholder of {{.Title}} in the template file and pass in a corresponding value when executing the template:

data := struct {
    Title string
}{
    Title: "Golang和Template包",
}

err = t.Execute(os.Stdout, data)
if err != nil {
    log.Fatal(err)
}

In the above example , we pass a structure containing the Title field as data to the template. ExecuteThe function merges the data with the template and outputs the merged result to standard output.

In addition to passing data to the template, we can also use conditional judgment and loop iteration in the template. For example, we can use the {{if .IsAdmin}} and {{range .Users}} syntax to implement conditional judgment and loop iteration:

{{if .IsAdmin}}
    <h1>Welcome, Admin!</h1>
{{else}}
    <h1>Welcome, Guest!</h1>
{{end}}

<ul>
    {{range .Users}}
        <li>{{.Name}}</li>
    {{end}}
</ul>

above In the example, we use the .IsAdmin field to determine whether the user is an administrator, and display different welcome messages based on the determination results. At the same time, we iterate through the user list through the .Users field to display the name of each user.

Summary:

By using Golang’s built-in html/template package, we can easily build reusable HTML templates. Templates can be used to dynamically insert dynamic data into predefined HTML structures, allowing us to flexibly generate various types of page content. At the same time, the template also supports functions such as conditional judgment and loop iteration, allowing us to build complex page layouts and interactions.

Whether it is used to build web applications or generate HTML reports, the Template package is a powerful and easy-to-use tool in Golang. We hope that through the introduction and sample code of this article, readers can better understand and flexibly use the Template package to build their own HTML templates.

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