Struct frame_support::migrations::RemovePallet

pub struct RemovePallet<P: Get<&'static str>, DbWeight: Get<RuntimeDbWeight>>(_);

RemovePallet is a utility struct used to remove all storage items associated with a specific pallet.

This struct is generic over two parameters:

• P is a type that implements the Get trait for a static string, representing the pallet’s name.
• DbWeight is a type that implements the Get trait for RuntimeDbWeight, providing the weight for database operations.

On runtime upgrade, the on_runtime_upgrade function will clear all storage items associated with the specified pallet, logging the number of keys removed. If the try-runtime feature is enabled, the pre_upgrade and post_upgrade functions can be used to verify the storage removal before and after the upgrade.

Examples:

construct_runtime! {
	pub enum Runtime
	{
		System: frame_system::{Pallet, Call, Storage, Config<T>, Event<T>} = 0,

		SomePalletToRemove: pallet_something::{Pallet, Call, Storage, Event<T>} = 1,
		AnotherPalletToRemove: pallet_something_else::{Pallet, Call, Storage, Event<T>} = 2,

		YourOtherPallets...
	}
};

parameter_types! {
		pub const SomePalletToRemoveStr: &'static str = "SomePalletToRemove";
		pub const AnotherPalletToRemoveStr: &'static str = "AnotherPalletToRemove";
}

pub type Migrations = (
	RemovePallet<SomePalletToRemoveStr, RocksDbWeight>,
	RemovePallet<AnotherPalletToRemoveStr, RocksDbWeight>,
	AnyOtherMigrations...
);

pub type Executive = frame_executive::Executive<
	Runtime,
	Block,
	frame_system::ChainContext<Runtime>,
	Runtime,
	Migrations
>;

WARNING: RemovePallet has no guard rails preventing it from bricking the chain if the operation of removing storage for the given pallet would exceed the block weight limit.

If your pallet has too many keys to be removed in a single block, it is advised to wait for a multi-block scheduler currently under development which will allow for removal of storage items (and performing other heavy migrations) over multiple blocks (see https://github.com/paritytech/substrate/issues/13690).

Trait Implementations

impl<P: Get<&'static str>, DbWeight: Get<RuntimeDbWeight>> OnRuntimeUpgrade for RemovePallet<P, DbWeight>

fn on_runtime_upgrade() -> Weight

See Hooks::on_runtime_upgrade.

fn pre_upgrade() -> Result<Vec<u8>, TryRuntimeError>

See Hooks::pre_upgrade.

fn post_upgrade(_state: Vec<u8>) -> Result<(), TryRuntimeError>

See Hooks::post_upgrade.

fn try_on_runtime_upgrade(checks: bool) -> Result<Weight, TryRuntimeError>

The expected and default behavior of this method is to handle executing pre_upgrade -> on_runtime_upgrade -> post_upgrade hooks for a migration.