Last time, xdm shared the simple method in the http package in GO web development, and there is a template at the end, I will add it here
Go directly to the case
template
- We write a server-side demo in main.go, and use templates to write winter data into html files
- Correspondingly, you need to write an html file and set the data location that needs 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 simulated data
p1 := Person{
Name: "xmt 1 No",
Title: "1 No. Visualizer",
Age: 18,
}
p2 := Person{
Name: "xmt 2 No",
Title: "2 No. Visualizer",
Age: 15,
}
p3 := Person{
Name: "xmt 3 No",
Title: "3 No. Visualizer",
Age: 29,
}
pp = append(pp, p1, p2, p3)
// write data to the template
err := myTemp.Execute(w, pp)
if err != nil {
fmt.Println("Execute err ；%v", err)
return
}
}
func main() {
//Initialize the template
var err error
myTemp, err = template.ParseFiles("./index.html")
if err != nil {
fmt.Println("ParseFiles err ；%v", err)
return
}
//Register a function that processes templates and enable listening
http.HandleFunc("/", userInfo)
err = http.ListenAndServe("0.0.0.0:9999", nil)
if err != nil {
fmt.Println("ListenAndServe err ；%v", err)
return
}
}
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>
The above code is also relatively simple. You can start the server by running main.go directly. We only need to access it in the browser.
http://localhost:8888/
You can see the effect of our html display, the data is dynamic
In addition, let's take a look at the mysql database used in go web
Mysql
Connect to the database
To operate the database, the basic steps are as follows
- First open, then ping, you must be able to connect to the MySQL database after the ping passes
- To write mysql code, you must import this package _ "github.com/go-sql-driver/mysql", you need to execute the init function in mysql first
Remember to fill in your mysql password here. If you think the password is hard to remember, you can set the password to 123456 for learning and practice
package main import ( "database/sql" "fmt" _ "github.com/go-sql-driver/mysql" // Exception after commenting out _ call initialization function ) func main() { //Open the mysql database to connect, you must ping to connect to the mysql database db, err := sql.Open("mysql", "root:xxxxxx@tcp(127.0.0.1:3306)/go_test?charset=utf8mb4") if err != nil { fmt.Println("Open err : ", err) return } err = db.Ping() if err != nil { fmt.Println("Ping err : ", err) return } db.Close() }
Here we can see charset=utf8mb4 , here is to set the character encoding format to utf8mb4 , mainly for
What needs to be said here is that basically our current mysql encoding settings are all set to utf8mb4 character set because it supports 4-byte Unicode characters
When Unicode was not perfect in the early days, UTF8 was used, which only needed a maximum of 3 bytes to represent Unicode characters
Increase
Do data addition operations and 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)
if err != nil {
fmt.Println("Exec err : ", err)
return
}
//The id of the inserted data
id, err := ret.LastInsertId()
if err != nil {
fmt.Println("LastInsertId err : ", err)
return
}
fmt.Println("LastInsertId == ", id)
//The number of rows affected by this operation
rows, err := ret.RowsAffected()
if err != nil {
fmt.Println("RowsAffected err : ", err)
return
}
fmt.Println("rows == ", rows)
}After executing the insert statement, you can get the id of the successfully inserted data and the number of rows affected by the inserted data through the inserted result
delete
Deleting data is relatively simple. Similarly, we can get the result of deleting data to obtain the number of rows affected by it, etc.
func deletePiceInfo(db *sql.DB) {
// ? as a placeholder
sqlInfo := "delete from user where id= xx "
ret, err := db.Exec(sqlInfo)
if err != nil {
fmt.Println("Exec err : ", err)
return
}
//The number of rows affected by this operation
rows, err := ret.RowsAffected()
if err != nil {
fmt.Println("RowsAffected err : ", err)
return
}
fmt.Println("rows == ", rows)
}Revise
func updatePiceInfo(db *sql.DB) {
// ? as a placeholder
sqlInfo := "update user set name='xxx' where id=xx"
ret, err := db.Exec(sqlInfo)
if err != nil {
fmt.Println("Exec err : ", err)
return
}
//The number of rows affected by this operation
rows, err := ret.RowsAffected()
if err != nil {
fmt.Println("RowsAffected err : ", err)
return
}
fmt.Println("rows == ", rows)
}Look, the modification operation is similar to other addition and deletion operations, and the writing method is basically the same, and it is relatively simple
Inquire
For query operations, there should be relatively more operations used in database operations. If go operates mysql queries, there are simply two points to note:
- The rows obtained after Query need to remember to close
- After calling the query data, you need to remember to call the Scan method immediately, otherwise the held database connection 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)
if err != nil {
fmt.Println("Exec err : ", err)
return
}
// VERY IMPORTANT: Closing rows releases held database connections
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)
}
}Welcome to like, follow and collect
Friends, your support and encouragement is my motivation to keep sharing and improve quality
Ok, that's it for this time
Technology is open, and our mentality should be even more open. Embrace change, live in the sun, and strive to move forward.
I am A Bing Yunyuan, welcome to like, follow and collect, see you next time~