Connect to OceanBase Database by using SeaORM

cargo new sea-orm-oceanbase-demo
cd sea-orm-oceanbase-demo

[package]
name = "sea-orm-oceanbase-demo"
version = "0.1.0"
edition = "2021"

[dependencies]
tokio = { version = "1.0", features = ["full"] }
sea-orm = { version = "0.12", features = [
    "sqlx-mysql",
    "runtime-tokio-rustls",
    "macros",
    "with-json"
] }
sea-orm-migration = "0.12"
serde = { version = "1.0", features = ["derive"] }
dotenv = "0.15"
async-std = { version = "1.12", features = ["attributes"] }
chrono = "0.4"

DATABASE_URL=mysql://username:password@localhost:2881/database_name

// src/entities/mod.rs
pub mod user;

// src/entities/user.rs
use sea_orm::entity::prelude::*;
use serde::{Deserialize, Serialize};

#[derive(Clone, Debug, PartialEq, DeriveEntityModel, Serialize, Deserialize)]
#[sea_orm(table_name = "users")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: i32,
    pub name: String,
    pub email: String,
    pub created_at: DateTimeUtc,
    pub updated_at: DateTimeUtc,
}

#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
pub enum Relation {}

impl ActiveModelBehavior for ActiveModel {}

use sea_orm::*;
use std::env;
use dotenv::dotenv;

pub async fn establish_connection() -> Result<DatabaseConnection, DbErr> {
    dotenv().ok();
    let database_url = env::var("DATABASE_URL").expect("DATABASE_URL must be set");
    Database::connect(&database_url).await
}

use crate::entities::user;
use sea_orm::*;
use chrono::Utc;

pub struct UserService;

impl UserService {
    // Create a user
    pub async fn create_user(
        db: &DatabaseConnection,
        name: String,
        email: String,
    ) -> Result<user::Model, DbErr> {
        let new_user = user::ActiveModel {
            name: Set(name),
            email: Set(email),
            created_at: Set(Utc::now()),
            updated_at: Set(Utc::now()),
            ..Default::default()
        };

        new_user.insert(db).await
    }

    // Get a single user
    pub async fn get_user(
        db: &DatabaseConnection,
        id: i32,
    ) -> Result<Option<user::Model>, DbErr> {
        user::Entity::find_by_id(id).one(db).await
    }

    // Update a user
    pub async fn update_user(
        db: &DatabaseConnection,
        id: i32,
        name: Option<String>,
        email: Option<String>,
    ) -> Result<user::Model, DbErr> {
        let mut user: user::ActiveModel = user::Entity::find_by_id(id)
            .one(db)
            .await?
            .ok_or_else(|| DbErr::Custom("User not found".to_owned()))?
            .into();

        if let Some(name) = name {
            user.name = Set(name);
        }
        if let Some(email) = email {
            user.email = Set(email);
        }
        user.updated_at = Set(Utc::now());

        user.update(db).await
    }

    // Delete a user
    pub async fn delete_user(
        db: &DatabaseConnection,
        id: i32,
    ) -> Result<DeleteResult, DbErr> {
        let user: user::ActiveModel = user::Entity::find_by_id(id)
            .one(db)
            .await?
            .ok_or_else(|| DbErr::Custom("User not found".to_owned()))?
            .into();

        user.delete(db).await
    }

    // Get all users
    pub async fn get_all_users(
        db: &DatabaseConnection,
    ) -> Result<Vec<user::Model>, DbErr> {
        user::Entity::find().all(db).await
    }
}

mod entities;
mod db;
mod user_service;

use sea_orm::{DatabaseConnection, DbErr, Statement, ConnectionTrait};
use user_service::UserService;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Establish a database connection.
    println!("Connecting to database...");
    let db = db::establish_connection().await?;
    println!("Database connected successfully!");

    // Create tables (if they do not exist).
    println!("Creating tables if not exist...");
    create_tables(&db).await?;
    println!("Tables created successfully!");

    // Create users.
    println!("Inserting sample data...");

    let users_to_create = vec![
        ("Alice", "alice@example.com"),
        ("Bob", "bob@example.com"),
        ("Charlie", "charlie@example.com"),
    ];

    for (name, email) in users_to_create {
        println!("Creating user: {} <{}>", name, email);
        match UserService::create_user(
            &db,
            name.to_string(),
            email.to_string()
        ).await {
            Ok(user) => println!("Created user: {} <{}>", user.name, user.email),
            Err(e) => eprintln!("Error creating user: {}", e),
        }
    }

    // Retrieve and print all users.
    println!("\nCurrent users in database:");
    match UserService::get_all_users(&db).await {
        Ok(users) => {
            for user in users {
                println!("ID: {}, Name: {}, Email: {}, Created: {}, Updated: {}",
                    user.id, user.name, user.email, user.created_at, user.updated_at);
            }
        },
        Err(e) => eprintln!("Error fetching users: {}", e),
    }

    Ok(())
}

async fn create_tables(db: &DatabaseConnection) -> Result<(), DbErr> {
    let stmt = r#"
    CREATE TABLE IF NOT EXISTS users (
        id INT AUTO_INCREMENT PRIMARY KEY,
        name VARCHAR(255) NOT NULL,
        email VARCHAR(255) NOT NULL UNIQUE,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
    "#;

    db.execute(Statement::from_string(
        db.get_database_backend(),
        stmt.to_owned(),
    ))
    .await?;

    Ok(())
}

cargo run

Connecting to database...
Database connected successfully!
Creating tables if not exist...
Tables created successfully!
Inserting sample data...
Creating user: Alice <alice@example.com>
Creating user: Bob <bob@example.com>
Creating user: Charlie <charlie@example.com>

Current users in database:
ID: 1, Name: Alice, Email: alice@example.com, Created: 2025-05-27 09:47:01 UTC, Updated: 2025-05-27 09:47:01 UTC
ID: 2, Name: Bob, Email: bob@example.com, Created: 2025-05-27 09:47:01 UTC, Updated: 2025-05-27 09:47:01 UTC
ID: 3, Name: Charlie, Email: charlie@example.com, Created: 2025-05-27 09:47:01 UTC, Updated: 2025-05-27 09:47:01 UTC