Attribute Macro genesis_build

#[genesis_build]

Allows you to define how the state of your pallet at genesis is built. This takes as input the GenesisConfig type (as self) and constructs the pallet’s initial state.

The fields of the GenesisConfig can in turn be populated by the chain-spec.

Example

#[frame_support::pallet]
pub mod pallet {
    #[pallet::genesis_config]
    #[derive(frame_support::DefaultNoBound)]
    pub struct GenesisConfig<T: Config> {
        foo: Vec<T::AccountId>
    }

    #[pallet::genesis_build]
    impl<T: Config> BuildGenesisConfig for GenesisConfig<T> {
        fn build(&self) {
            // use &self to access fields.
            let foo = &self.foo;
            todo!()
        }
    }
}

Former Usage

Prior to https://github.com/paritytech/substrate/pull/14306, the following syntax was used. This is deprecated and will soon be removed.

#[frame_support::pallet]
pub mod pallet {
    #[pallet::genesis_config]
    #[derive(frame_support::DefaultNoBound)]
    pub struct GenesisConfig<T: Config> {
		foo: Vec<T::AccountId>
	}

    #[pallet::genesis_build]
    impl<T: Config> GenesisBuild<T> for GenesisConfig<T> {
        fn build(&self) {
            todo!()
        }
    }
}

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Documentation for this macro can be found at frame_support::pallet_macros::genesis_build.