# ergol
[](https://github.com/polymny/ergol/actions?query=workflow%3Abuild) [](https://docs.rs/ergol/) [Book](https://ergol-rs.github.io)
This crate provides the `#[ergol]` macro. It allows to persist the data in a
database. For example, you just have to write
```rust
use ergol::prelude::*;
#[ergol]
pub struct User {
#[id] pub id: i32,
#[unique] pub username: String,
pub password: String,
pub age: Option<i32>,
}
```
and the `#[ergol]` macro will generate most of the code you will need. You'll
then be able to run code like the following:
```rust
// Drop the user table if it exists
User::drop_table().execute(&client).await.ok();
// Create the user table
User::create_table().execute(&client).await?;
// Create a user and save it into the database
let mut user: User = User::create("thomas", "pa$$w0rd", Some(28)).save(&client).await?;
// Change some of its fields
*user.age.as_mut().unwrap() += 1;
// Update the user in the database
user.save(&client).await?;
// Fetch a user by its username thanks to the unique attribute
let user: Option<User> = User::get_by_username("thomas", &client).await?;
// Select all users
let users: Vec<User> = User::select().execute(&client).await?;
```
See [the book](https://ergol-rs.github.io) for more information.