Models
Models is an implementation for a SQL migration management tool. It supports PostgreSQL, MySQL, and SQLite.
Quick Start
install the CLI by running the following command:
$ cargo install models-cli
Now run the following command to create an environment file with the DATABASE_URL variable set:
$ echo "DATABASE_URL=sqlite://database.db" > .env
Alternatively it can be set as a environment variable with the following command:
$ export DATABASE_URL=sqlite://database.db
We now can create the database running the following command:
$ models database create
This command will have created an SQLite file called database.db. You can now derive the Model trait on your structures, and models will manage the migrations for you. For example, write at src/main.rs:
#![allow(dead_code)]
use models::Model;
#[derive(Model)]
struct User {
#[primary_key]
id: i32,
#[unique]
email: String,
password: String,
#[default(0)]
is_admin: bool,
}
#[derive(Model)]
struct Post {
#[primary_key]
id: i32,
#[foreign_key(User.id)]
author: String,
#[default("<Untitled Post>")]
title: String,
content: String,
}
#[derive(Model)]
struct PostLike {
#[foreign_key(User.id, on_delete="cascade")]
#[primary_key(post_id)]
user_id: i32,
#[foreign_key(Post.id, on_delete="cascade")]
post_id: i32,
}
#[derive(Model)]
struct CommentLike {
#[foreign_key(User.id)]
#[primary_key(comment_id)]
user_id: i32,
#[foreign_key(Comment.id)]
comment_id: i32,
#[default(0)]
is_dislike: bool,
}
#[derive(Model)]
struct Comment {
#[primary_key]
id: i32,
#[foreign_key(User.id)]
author: i32,
#[foreign_key(Post.id)]
post: i32,
}
fn main() {}
If you now run the following command, your migrations should be automatically created.
$ models generate
The output should look like this:
Generated: migrations/1632280793452 user
Generated: migrations/1632280793459 post
Generated: migrations/1632280793465 postlike
Generated: migrations/1632280793471 comment
Generated: migrations/1632280793476 commentlike
You can check out the generated migrations at the migrations/ folder. To execute these migrations you can execute the following command:
models migrate run
The output should look like this:
Applied 1631716729974/migrate user (342.208µs)
Applied 1631716729980/migrate post (255.958µs)
Applied 1631716729986/migrate comment (287.792µs)
Applied 1631716729993/migrate postlike (349.834µs)
Applied 1631716729998/migrate commentlike (374.625µs)
If we later modify those structures in our application, we can generate new migrations to update the tables.
Reverting migration
Models can generate down migrations with the -r flag. Note that simple and reversible migrations cannot be mixed:
$ models generate -r
In order to revert the last migration executed you can run:
$ models migrate revert
If you later want to see which migrations are yet to be applied you can also excecute:
$ models migrate info
Avaibale Attributes
primary_key
It's used to mark the primary key fo the table.
#[primary_key]
id: i32,
for tables with multicolumn primary keys, the following syntax is used:
#[primary_key(second_id)]
first_id: i32,
second_id: i32,
This is equivalent to
PRIMARY KEY (first_id, second_id),
foreign_key
It is used to mark a foreign key constraint.
#[foreign_key(User.id)]
user: i32,
It can also specify on_delete and on_update constraints:
#[foreign_key(User.id, on_delete="cascade")]
user_id: i32,
This is equivalent to
FOREIGN KEY (user_id) REFERENCES user (id) ON DELETE CASCADE,
default
It can be used to set a default value for a column.
#[default(false)] // when using SQLite use 0 or 1
is_admin: bool,
#[default("")]
text: String,
#[default(0)]
number: i32,
unique
It is used to mark a unique constraint.
#[unique]
email: String,
For multicolumn unique constraints the following syntax is used:
#[unique(post_id)]
user_id: String,
post_id: i32,
This is equivalent to
UNIQUE (user_id, post_id),
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