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XDM was shared last time with a simple method used in the HTTP package in GO Web development, and finally there is a template, which is added here

Go straight to case

The template

  • We’ll write a server demo in **main.go **, using the template to write the winter data to an HTML file
  • Write an HTML file and set the data location for template injection

main.go

package main

import (
	"fmt"
	"html/template"
	"net/http"
)

var myTemp *template.Template

type Person struct {
	Name  string
	Title string
	Age   int
}

// Start processing data and responding
func userInfo(w http.ResponseWriter, req *http.Request) {
	defer req.Body.Close()

	var pp []Person
    // Simple simulation data
	p1 := Person{
		Name:  "XMT 1",
		Title: "Exhibit 1",
		Age:   18,
	}
	p2 := Person{
		Name:  "XMT 2",
		Title: "Exhibit 2",
		Age:   15,
	}
	p3 := Person{
		Name:  "XMT 3",
		Title: "Exhibit 3",
		Age:   29,
	}

	pp = append(pp, p1, p2, p3)

    // Write data to the template
	err := myTemp.Execute(w, pp)
	iferr ! =nil {
		fmt.Println("The Execute err; %v", err)
		return}}func main(a) {

	// Initialize the template
	var err error
	myTemp, err = template.ParseFiles("./index.html")
	iferr ! =nil {
		fmt.Println("ParseFiles err ；%v", err)
		return
	}

	// Register functions that process templates and enable listening
	http.HandleFunc("/", userInfo)
	err = http.ListenAndServe("0.0.0.0:9999".nil)
	iferr ! =nil {
		fmt.Println("ListenAndServe err ；%v", err)
		return}}Copy the code

index.html

<html>
    <head>

    </head>
    <body>
        <p>hello world</p>
        <table border="1" align="center" width="600px">
            <tr>
                <td>{{.Name}}</td> <td>{{.Age}}</td><td>{{.Title}}</td>
            </tr>
        </table>
    </body>
</html>

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The above code is also relatively simple, directly run main.go can start the server, we only need to access in the browser

http://localhost:8888/
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You can see the effect of our HTML display, the data is dynamic

Also, let’s take a look at the mysql database used in Go Web

Mysql

Connecting to a Database

Operation database, basically is the following several steps

  • Open the MySQL database and ping the MySQL database

  • To write mysql code, you must import this package _ “github.com/go-sql-driver/mysql”, you need to execute mysql init function first

  • Enter your own mysql password. If you cannot remember the password, set the password to 123456 for learning and practice

    package main

import (
	"database/sql"
	"fmt"

	_ "github.com/go-sql-driver/mysql" // Call the initialization function after the exception is commented out

)

func main(a) {
	// If you want to connect to the mysql database, you must ping the mysql database
	db, err := sql.Open("mysql"."Root: XXXXXX @ TCP/go_test (127.0.0.1:3306)? charset=utf8mb4")
	iferr ! =nil {
		fmt.Println("Open err : ", err)
		return
	}

	err = db.Ping()
	iferr ! =nil {
		fmt.Println("Ping err : ", err)
		return
	}
	db.Close()
}
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Here we can see charset= UTf8MB4, here we set the character encoding format to UTF8MB4, mainly used for

It should be noted that basically our mysql encoding is set to the UTF8MB4 character set because it supports 4-byte Unicode characters

In the early days, when Unicode was not perfect, UTF8 was used, requiring only up to three bytes to represent Unicode characters

increase

Do a data add operation to insert data into the database

  • Here we use placeholders to insert data
  • Fill in the standard SQL statement in the sqlInfo variable
func insertPiceInfo(db *sql.DB) {
	/ /? As a placeholder
	sqlInfo := "insert into user(name,age)values(? ,?) "
	ret, err := db.Exec(sqlInfo, "xxx".19)
	iferr ! =nil {
		fmt.Println("Exec err : ", err)
		return
	}

	// Insert the id of data
	id, err := ret.LastInsertId()
	iferr ! =nil {
		fmt.Println("LastInsertId err : ", err)
		return
	}

	fmt.Println("LastInsertId == ", id)

	// Number of rows affected by this operation
	rows, err := ret.RowsAffected()
	iferr ! =nil {
		fmt.Println("RowsAffected err : ", err)
		return
	}
	fmt.Println("rows == ", rows)

}
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After the insert statement is executed, you can obtain the ID of the successful data insertion and the number of rows affected by the data insertion according to the insert result

delete

Deleting data is easier, and again we can get the result of deleting data to get the number of rows that are affected and so on

func deletePiceInfo(db *sql.DB) {
	/ /? As a placeholder
	sqlInfo := "delete from user where id= xx "
	ret, err := db.Exec(sqlInfo)
	iferr ! =nil {
		fmt.Println("Exec err : ", err)
		return
	}

	// Number of rows affected by this operation
	rows, err := ret.RowsAffected()
	iferr ! =nil {
		fmt.Println("RowsAffected err : ", err)
		return
	}
	fmt.Println("rows == ", rows)

}
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Modify the

func updatePiceInfo(db *sql.DB) {
	/ /? As a placeholder
	sqlInfo := "update user set name='xxx' where id=xx"
	ret, err := db.Exec(sqlInfo)
	iferr ! =nil {
		fmt.Println("Exec err : ", err)
		return
	}

	// Number of rows affected by this operation
	rows, err := ret.RowsAffected()
	iferr ! =nil {
		fmt.Println("RowsAffected err : ", err)
		return
	}
	fmt.Println("rows == ", rows)

}
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See, modify operations and other add, delete operations similar, written basically the same, but also relatively simple

The query

Query operation, should be used in the database operation relatively more operations, go operation mysql query, simple there are two points to note:

  • The rows obtained after Query need to remember close
  • Remember to call the Scan method immediately after the query data is called, otherwise the database link held will not be released
type myInfo struct{
	id int
	name string
	age int
}

func selectInfo(db *sql.DB) {
	sqlInfo := "select * from user"
	rows, err := db.Query(sqlInfo)
	iferr ! =nil {
		fmt.Println("Exec err : ", err)
		return
	}
    // Very important: Close rows to release the database link held
	defer rows.Close()
	// Output the number of rows queried

	for rows.Next(){
		var u myInfo
		rows.Scan(&u.id,&u.name,&u.age)
		fmt.Printf("id = %d, name = %s, age = %d\n",u.id,u.name,u.age)
	}

}
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