Expand description
The CheckMetadataHash
signed extension.
The extension for optionally checking the metadata hash. For information how it works and what
it does exactly, see the docs of CheckMetadataHash
.
§Integration
As any signed extension you will need to add it to your runtime signed extensions:
ⓘ
mod add_metadata_hash_extension {
frame_support::construct_runtime! {
pub enum Runtime {
System: frame_system,
}
}
/// The `SignedExtension` to the basic transaction logic.
pub type SignedExtra = (
frame_system::CheckNonZeroSender<Runtime>,
frame_system::CheckSpecVersion<Runtime>,
frame_system::CheckTxVersion<Runtime>,
frame_system::CheckGenesis<Runtime>,
frame_system::CheckMortality<Runtime>,
frame_system::CheckNonce<Runtime>,
frame_system::CheckWeight<Runtime>,
// Add the `CheckMetadataHash` extension.
// The position in this list is not important, so we could also add it to beginning.
frame_metadata_hash_extension::CheckMetadataHash<Runtime>,
);
/// In your runtime this will be your real address type.
type Address = ();
/// In your runtime this will be your real signature type.
type Signature = ();
/// Unchecked extrinsic type as expected by this runtime.
pub type UncheckedExtrinsic =
sp_runtime::generic::UncheckedExtrinsic<Address, RuntimeCall, Signature, SignedExtra>;
}
As the extension requires the RUNTIME_METADATA_HASH
environment variable to be present at
compile time, it requires a little bit more setup. To have this environment variable available
at compile time required to tell the substrate-wasm-builder
to do so:
ⓘ
fn enable_metadata_hash_in_wasm_builder() {
substrate_wasm_builder::WasmBuilder::init_with_defaults()
// Requires the `metadata-hash` feature to be activated.
// You need to pass the main token symbol and its number of decimals.
.enable_metadata_hash("TOKEN", 12)
// The runtime will be build twice and the second time the `RUNTIME_METADATA_HASH`
// environment variable will be set for the `CheckMetadataHash` extension.
.build()
}
As generating the metadata hash requires to compile the runtime twice, it is recommended to only enable the metadata hash generation when doing a build for a release or when you want to test this feature.
Structs§
- Extension for optionally verifying the metadata hash.