How to implement data input validation function in Dart using MySQL

How to implement data input validation function in Dart using MySQL

When developing web applications, data input validation is a very important part. MySQL is a commonly used relational database, and Dart is a popular web development language. This article will introduce how to use MySQL to implement data input validation in Dart.

1. Environment setup
First, we need to install the MySQL database and create a database and corresponding data table to store the data entered by the user. You can use the following SQL statement to create a data table:

CREATE TABLE users (

id INT AUTO_INCREMENT PRIMARY KEY,
username VARCHAR(50) NOT NULL,
email VARCHAR(50) NOT NULL,
password VARCHAR(50) NOT NULL

);

In Dart, we use the dart_mysql library to connect to the MySQL database. Add the following dependencies in the pubspec.yaml file:

dependencies:
mysql1: ^0.15.0

Then install the dependencies by running flutter pub get.

2. Connect to the MySQL database
In the Dart code, we first need to import the mysql1 library and create a connection to the database. The following is a sample code to connect to a MySQL database:

import 'package:mysql1/mysql1.dart';

Future connectToDatabase() async {
final settings = ConnectionSettings (

host: 'localhost',
port: 3306,
user: 'root',
password: 'password',
db: 'database_name',

);

final conn = await MySqlConnection.connect(settings);
return conn;
}

3. Data input verification
Before we process the data, we need to verify that the data entered by the user meets the requirements. The following is a sample code to verify whether the username is legal:

bool isUsernameValid(String username) {
// The username length must be between 4 and 20 characters
if (username.length < 4 || username.length > 20) {

return false;

}

// The username can only contain letters, numbers and underscores
final regex = RegExp(r'^ [a-zA-Z0-9_] $');
if (!regex.hasMatch(username)) {

return false;

}

return true;
}

Similarly, we can write other verification functions to verify email and password. For example, we can use regular expressions to verify the legitimacy of the email, use the string length to verify the strength of the password, etc.

4. Insert data into the MySQL database
Once we have verified the data entered by the user, we can insert it into the MySQL database. The following is a sample code to insert user data into the database:

Future insertUser(String username, String email, String password) async {
final conn = await connectToDatabase();

final sql = 'INSERT INTO users (username, email, password) VALUES (?, ?, ?)';
final values ​​= [username, email, password];

await conn. query(sql, values);

await conn.close();
}

When inserting data, we use "?" as a placeholder and then pass the actual value Give the second parameter to the query method. This avoids SQL injection attacks.

5. Complete sample code
The following is a complete sample code that demonstrates how to use MySQL to implement data input verification function in Dart.

import 'package:mysql1/mysql1.dart';

bool isUsernameValid(String username) {
// Logic of validating username
}

bool isEmailValid(String email) {
// Logic for verifying email
}

bool isPasswordValid(String password) {
// Logic for verifying password
}

Future connectToDatabase() async {
final settings = ConnectionSettings(

host: 'localhost',
port: 3306,
user: 'root',
password: 'password',
db: 'database_name',

);

final conn = await MySqlConnection.connect(settings);
return conn ;
}

Future insertUser(String username, String email, String password) async {
final conn = await connectToDatabase();

final sql = 'INSERT INTO users (username, email, password) VALUES (?, ?, ?)';
final values ​​= [username, email, password];

await conn.query(sql, values);

await conn.close();
}

void main() async {
final username = 'test';
final email = 'test@example.com ';
final password = 'password';

if (!isUsernameValid(username)) {

print('Invalid username');
return;

}

if (!isEmailValid(email)) {

print('Invalid email');
return;

}

if (!isPasswordValid(password)) {

print('Invalid password');
return;

}

await insertUser(username, email, password);

print('User inserted successfully');
}

6. Summary
This article introduces how to use MySQL to implement data input verification function in Dart. We first created a connection to the database and then wrote a validation function to validate the data entered by the user. Finally, the user data is inserted into the database. This example is just a simple example and can be extended and modified according to actual needs. Hope this article is helpful to you!

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