[Go] Detailed explanation of Template application in go language

Table of contents

Detailed explanation of Template application in go language

2. A simple example to demonstrate how to use the text/template package

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Detailed explanation of Template application in go language

Templates in the Go language are widely used, and they are used to generate dynamic content, render HTML pages, generate text files, and so on. In Go language, we can use text/templateand html/templatepackage to deal with templates.

The following is a detailed explanation of template application in Go language:

1. Template syntax: The template syntax of the Go language uses double curly braces { {}}to represent template instructions. In templates, we can use variables, control structures and function calls etc. For example, { {.Name}}represents a variable placeholder that will be replaced by the actual value at execution time.

2. Creation of template objects: We can use template.New()methods to create a template object, and use Parse()methods to parse template strings or load templates from files. The parsed template object can be used to execute the template.

3. Data passing and rendering: We can pass data to the template for rendering. This can be done by passing the data as the second parameter to Execute()the or ExecuteTemplate()method. Data can be structs, maps, or custom types. In the template, we can .refer to the passed data by .

4. Control Structures: Templates support control structures such as conditional statements, loops, and branches. We can implement control structures using directives such as if-else, range, and . withThese directives allow us to control the rendering of templates based on the condition and structure of the data.

5. Function call: Built-in functions and custom functions can be called in the template. The built-in functions include common functions such as string processing, date and time processing, and type conversion. We can also Funcs()register custom functions via methods to be called in templates. You can use the pipe symbol |to call a function and pass the output of the previous instruction as an argument to the function.

6. Nested templates: Templates in the Go language support nesting of templates. By defining and calling sub-templates, we can realize the reuse of templates. Templates can be Define()defined using methods and then Template()invoked using methods.

7. Custom delimiters: By default, templates use double curly braces { {}}as identifiers. However, we can Delims()customize the separator using the method. This is useful for embedding template engines of other languages ​​in templates.

8. Security considerations: When using templates, we should pay attention to security. Especially when handling user input, you need to avoid injecting malicious content. Go packages html/templateautomatically escape special characters to provide stronger security.

The above are some detailed explanations of template application in Go language. By using templates, we can easily generate dynamic content and achieve code reusability and scalability.

2. Simple examples to demonstrate how to use text/templatethe package

package main

import (
	"os"
	"text/template"
)

type Person struct {
	Name string
	Age  int
}

func main() {
	person := Person{"Alice", 25}

	tmpl, err := template.New("person").Parse("Name: {
   
   {.Name}}, Age: {
   
   {.Age}}")
	if err != nil {
		panic(err)
	}

	err = tmpl.Execute(os.Stdout, person)
	if err != nil {
		panic(err)
	}
}

 In the above example, we defined a Personstruct, then created a template object and parsed the template string. The sums in the template string are placeholders { {.Name}}and { {.Age}}will be replaced by the actual values. Finally, we use Executethe method to apply the template to the struct and output the result to standard output.

Beyond this simple example, templates also support more complex operations, such as control flow constructs (conditional statements, loops, etc.), function calls, nested templates, and more. You can use the pipe symbol in templates |to call built-in or custom functions. You can also improve the reusability of templates by defining template fragments (partial) and template inheritance.

html/templatePackages text/templateare similar to packages, but specifically for generating HTML content, which automatically escapes special characters for stronger security.