Go web form validation

One of the principles of developing the web is that you cannot trust any information entered by the user, so it is very important to validate and filter the information entered by the user

Required fields

if len(r.Form["username"][0])==0{
	// handle empty
}

number

getint,err:=strconv.Atoi(r.Form.Get("age"))
if err!=nil{
	//The number conversion is wrong, then it may not be a number
}

// Next, you can determine the size range of this number
if getint >100 {
	//too big
}

if m, _ := regexp.MatchString("^[0-9]+$", r.Form.Get("age")); !m {
	return false
}

Convert numbers and regular matches

For performance, avoid regulars, regulars will have a matching time, multiple matching speeds will be slow, but it does not matter if the server is strong.

match Chinese

if m, _ := regexp.MatchString("^\\p{Han}+$", r.Form.Get("realname")); !m {
	return false
}

match english

if m, _ := regexp.MatchString("^[a-zA-Z]+$", r.Form.Get("engname")); !m {
	return false
}

match email

if m, _ := regexp.MatchString(`^([\w\.\_]{2,10})@(\w{1,}).([az]{2,4})$`, r.Form.Get("email")); !m { //Matches 2 to 10 alphanumeric underscores and dots, plus @ and then matches at least one alphanumeric underscore, plus . matches the letters az (at least 2 to 4 bit)
	fmt.Println("no")
}else{
	fmt.Println("yes")
}

cellphone number

if m, _ := regexp.MatchString(`^(1[3|4|5|8][0-9]\d{4,8})$`, r.Form.Get("mobile")); !m {
	return false
}

Judgment of drop-down menu

slice:=[]string{"haha","ccc","bca"} //Create a slice

v := r.Form.Get("fruit")
for _, item := range slice {
	if item == v {
		return true
	}
}
return false

checkbox to select different

slice:=[]string{"football","basketball","tennis"}
a:=Slice_diff(r.Form["interest"],slice)
if a == nil{
	return true
}

return false

ID number

//Verify 15 ID cards, 15 digits are all numbers
if m, _ := regexp.MatchString(`^(\d{15})$`, r.Form.Get("usercard")); !m {
	return false
}

//Verify the 18-digit ID card, the first 17 digits of the 18 digits are numbers, and the last digit is the check digit, which may be a number or the character X.
if m, _ := regexp.MatchString(`^(\d{17})([0-9]|X)$`, r.Form.Get("usercard")); !m {
	return false
}