Crate barrel [−] [src]
Powerful schema migration builder API in Rust.
Barrel is meant to make writing migrations for different databases as easy as possible. It has three primary models: the Migration which represents all changes and changes made on a database level, the Table and the Column.
When creating or altering tables a lambda which exposes &mut Table
is
provided for initialisation. Adding columns is then as easy as calling
add_column(...)
on the table.
Each column is statically typed and some types require some metadata in order
to compile the migration (for example Varchar(255)
). You can also provide
default types and override encodings, nullability or uniqueness of columns.
Some checks are performed at compile-time however most things (including)
correct default values) are only checked at runtime.
The following code is a simple example of how to get going with barrel
extern crate barrel; use barrel::*; use barrel::backend::Pg; fn main() { let mut m = Migration::new(); m.create_table("users", |t| { t.add_column("name", Type::Varchar(255)); t.add_column("age", Type::Integer); t.add_column("owns_plushy_sharks", Type::Boolean); }); }
barrel
also supports more advanced types, such as Foreign(...)
and Array(...)
however currently doesn't support nested Array types on
foreign keys (such as Array(Array(Foreign(...)))
). Each column addition
returns a Column object which can then be used to provide further
configuration.
To generate SQL strings you have two options. If you just want to run the
migration yourself simply run Migration::exec()
where you provide a
generic SqlGenerator
type according to your database backend
// Example for pgsql
m.make::<Pg>();
Alternatively, if you're a library developer and you want to more easily
embed barrel
into your library you can simply implement the
DatabaseExecutor
trait for a type of yours that knows how to execute SQL.
Running a migration with barrel
is then super easy.
m.execute(executor);
In this case executor
is your provided type which implements the required
trait. You can read more about this in the connectors
module docs.
Important: This crate is still early in development and the API might
change rapidely between pre-release versions. I will try as best I can to
include changes in the CHANGELOG
but can not guarantee perfect coverage.
Also, if there is missing or invalid documentation for this crate, PR's are always welcome 💚
Reexports
pub use table::Column; |
pub use table::Table; |
pub use table::TableMeta; |
pub use migration::Migration; |
Modules
backend |
A backend module which provides a few generic traits to implement SQL generation for different databases. |
connectors |
A simple module meant for library developers |
migration |
Core migration creation handler |
table |
A module that represents tables and columns |
Enums
DatabaseChange |
An enum set that represents a single change on a database |
TableChange |
An enum set that represents a single change on a table |
Type |
Type enum to specificy the |