README.md

Migratable

This project is a library used to have pallet-contracts-like migration schema for Substrate pallets.

Setup

1. Add the following statements:

   • #[migratable::pallet] in the pallet's module.
   • #[migratable::config] in the pallet's configuration.
   • #[migratable::hooks] in the pallet's hooks.

2. Declare the pallet's hooks impl block. There's no need to implement any function.

3. Make sure you add the corresponding storage version with the #[pallet::storage_version()] statement.

#[migratable::pallet]
#[frame_support::pallet]
pub mod pallet {
    // -- snip --

    #[migratable::config]
    #[pallet::config]
    pub trait Config: frame_system::Config {
        // -- snip --
    }

    const STORAGE_VERSION: StorageVersion = StorageVersion::new(1);

    #[pallet::pallet]
    #[pallet::storage_version(STORAGE_VERSION)]
    pub struct Pallet<T>(_);

    #[migratable::hooks]
    #[pallet::hooks]
    impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {}
}

4. When instantiating the pallet, make sure to add the migrations that apply. Some examples here.

impl my_pallet::Config for Runtime {
   // -- snip --
    
    type Migrations = (
        my_pallet::migration::v2::Migration<Self>,
        my_pallet::migration::v3::Migration<Self>,
        my_pallet::migration::v4::Migration<Self>,
        // add as many as needed
    );
}

5. Add the pallet's Migration struct to Executive:

pub type Executive = frame_executive::Executive<
   Runtime,
   Block,
   frame_system::ChainContext<Runtime>,
   Runtime,
   AllPalletsWithSystem,
   // make sure to add here the migration
   (
      my_pallet::pallet::Migration<Runtime>,
   ),
>;