Crate sqlx_models

sqlx-models

sqlx-modes is a work in progress implementation for a sql migration management tool for applications using sqlx. Beware, this is still under development, and some API’s may be broken in the future.

Basic Tutorial

install the CLI by running the following command:

$ cargo install sqlx-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

We now can create the database running the command:

$ sqlx database create

This command will have created an sqlite file called database.db. You can now derive the Model trait on your structures, and sqlx-models will manage the migrations for you. For example, write at src/main.rs:

#![allow(dead_code)]
use sqlx_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)]
    #[primary_key(post_id)]
    user_id: i32,
    #[foreign_key(Post.id)]
    post_id: i32,
}
 
#[derive(Model)]
struct CommentLike {
    #[foreign_key(User.id)]
    #[primary_key(comment)]
    user: i32,
    #[foreign_key(Comment.id)]
    comment: i32,
    #[default(false)]
    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.

$ sqlx migrate 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 commit this migrations you can execute the following command:

sqlx migrate run

The output should look like this:

Applied: migrations/1632280793452 user (569.208µs)
Applied: migrations/1632280793459 post (328.75µs)
Applied: migrations/1632280793465 postlike (436.542µs)
Applied: migrations/1632280793471 comment (288.625µs)
Applied: migrations/1632280793476 commentlike (318.208µs)

If we later modify those structures in our application, we can generate new migrations to update the tables.

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)] // if 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(hash)]
    user_id: String,
    post_id: i32,

This is equivalent to

    UNIQUE (user_id, post_id),

Derive Macros

Model