# surrealdb_migration_engine

[![crates.io](https://img.shields.io/crates/v/surrealdb_migration_engine.svg)](https://crates.io/crates/surrealdb_migration_engine)
[![License: MIT](https://img.shields.io/badge/license-MIT-purple.svg)](https://opensource.org/licenses/MIT)

A simple and powerful migration engine for [SurrealDB](https://github.com/surrealdb/surrealdb). All you need to get it working is the following:
```rust
#[derive(rust_embed::RustEmbed)]
#[folder = "migrations"]
struct MigrationFiles;

#[derive(rust_embed::RustEmbed)]
#[folder = "schema"]
struct SchemaFiles;

async fn main() {
    // create surealdb `client`

    surrealdb_migration_engine::run::<MigrationFiles,SchemaFiles>(&client).await?;

    // the rest of your code
}
```
## How It Works
`surrealdb_migration_engine` works on two concepts **Migrations** and **Schemas**. Migrations are queries (changes) to an apply to an existing schema. Schemas are queries that set up the db structure. Schemas and migrations reside in their own directory with each file being numbered in order e.g. `0001_add_age_to_user_table.surql`. Each of these directories is compiled with your binary with the help of the `rust_embed` crate. This means that the appropriate migrations or schema creation will happen at runtime. All migrations and schema changes are done in a single transaction, so if one fails, they all fail.

`surrealdb_migration_engine` creates a `migrations` table inside your database to track which migrations have ran. The logic flow works like this: 
- If the `migrations` table does not exist, run only the schema files, create a `migrations` table and add all of the current migration files to the table.
- If the `migrations` table does exist, run any migration files that are not in the `migrations` table and insert those migrations in the `migrations` table.

Simple yet very expressive!

## Uses
- Include `surrealdb_migration_engine` in your application so whenever you run your application, the schema is always up to date.
- Include `surrealdb_migration_engine` in a barebones executable that runs the necessary migrations or schema creation whenever you want them to occur.