Struct pallet_example_offchain_worker::pallet::Pallet

pub struct Pallet<T>(_);

The pallet implementing the on-chain logic.

Implementations

impl<T: Config> Pallet<T>

A public part of the pallet.

pub fn submit_price(
    origin: OriginFor<T>,
    price: u32
) -> DispatchResultWithPostInfo

Submit new price to the list.

This method is a public function of the module and can be called from within a transaction. It appends given price to current list of prices. In our example the offchain worker will create, sign & submit a transaction that calls this function passing the price.

The transaction needs to be signed (see ensure_signed) check, so that the caller pays a fee to execute it. This makes sure that it’s not easy (or rather cheap) to attack the chain by submitting excesive transactions, but note that it doesn’t ensure the price oracle is actually working and receives (and provides) meaningful data. This example is not focused on correctness of the oracle itself, but rather its purpose is to showcase offchain worker capabilities.

pub fn submit_price_unsigned(
    origin: OriginFor<T>,
    _block_number: T::BlockNumber,
    price: u32
) -> DispatchResultWithPostInfo

Submit new price to the list via unsigned transaction.

Works exactly like the submit_price function, but since we allow sending the transaction without a signature, and hence without paying any fees, we need a way to make sure that only some transactions are accepted. This function can be called only once every T::UnsignedInterval blocks. Transactions that call that function are de-duplicated on the pool level via validate_unsigned implementation and also are rendered invalid if the function has already been called in current “session”.

It’s important to specify weight for unsigned calls as well, because even though they don’t charge fees, we still don’t want a single block to contain unlimited number of such transactions.

This example is not focused on correctness of the oracle itself, but rather its purpose is to showcase offchain worker capabilities.

pub fn submit_price_unsigned_with_signed_payload(
    origin: OriginFor<T>,
    price_payload: PricePayload<T::Public, T::BlockNumber>,
    _signature: T::Signature
) -> DispatchResultWithPostInfo

impl<T: Config> Pallet<T>

pub fn prices() -> Vec<u32>

A vector of recently submitted prices.

This is used to calculate average price, should have bounded size.

impl<T: Config> Pallet<T>

pub fn next_unsigned_at() -> T::BlockNumber

Defines the block when next unsigned transaction will be accepted.

To prevent spam of unsigned (and unpayed!) transactions on the network, we only allow one transaction every T::UnsignedInterval blocks. This storage entry defines when new transaction is going to be accepted.

Trait Implementations

impl<T: Config> Callable<T> for Pallet<T>

type Call = Call<T>

impl<T> Clone for Pallet<T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for Pallet<T>

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Config> GetStorageVersion for Pallet<T>

fn current_storage_version() -> StorageVersion

Returns the current storage version as supported by the pallet.

fn on_chain_storage_version() -> StorageVersion

Returns the on-chain storage version of the pallet as stored in the storage.

impl<T: Config> Hooks<<T as Config>::BlockNumber> for Pallet<T>

fn offchain_worker(block_number: T::BlockNumber)

Offchain Worker entry point.

By implementing fn offchain_worker you declare a new offchain worker. This function will be called when the node is fully synced and a new best block is succesfuly imported. Note that it’s not guaranteed for offchain workers to run on EVERY block, there might be cases where some blocks are skipped, or for some the worker runs twice (re-orgs), so the code should be able to handle that. You can use Local Storage API to coordinate runs of the worker.

fn on_finalize(_n: BlockNumber)

The block is being finalized. Implement to have something happen.

fn on_idle(_n: BlockNumber, _remaining_weight: u64) -> u64

This will be run when the block is being finalized (before on_finalize). Implement to have something happen using the remaining weight. Will not fire if the remaining weight is 0. Return the weight used, the hook will subtract it from current weight used and pass the result to the next on_idle hook if it exists.

fn on_initialize(_n: BlockNumber) -> u64

The block is being initialized. Implement to have something happen.

fn on_runtime_upgrade() -> u64

Perform a module upgrade.

fn pre_upgrade() -> Result<(), &'static str>

Execute some pre-checks prior to a runtime upgrade.

fn post_upgrade() -> Result<(), &'static str>

Execute some post-checks after a runtime upgrade.

fn integrity_test()

Run integrity test.

impl<T: Config> IntegrityTest for Pallet<T>

fn integrity_test()

Run integrity test.

impl<T: Config> ModuleErrorMetadata for Pallet<T>

fn metadata() -> &'static [ErrorMetadata]

impl<T: Config> OffchainWorker<<T as Config>::BlockNumber> for Pallet<T>

fn offchain_worker(n: <T as Config>::BlockNumber)

This function is being called after every block import (when fully synced).

impl<T: Config> OnFinalize<<T as Config>::BlockNumber> for Pallet<T>

fn on_finalize(n: <T as Config>::BlockNumber)

The block is being finalized. Implement to have something happen.

impl<T: Config> OnGenesis for Pallet<T>

fn on_genesis()

Something that should happen at genesis.

impl<T: Config> OnIdle<<T as Config>::BlockNumber> for Pallet<T>

fn on_idle(n: <T as Config>::BlockNumber, remaining_weight: Weight) -> Weight

The block is being finalized. Implement to have something happen in case there is leftover weight. Check the passed remaining_weight to make sure it is high enough to allow for your pallet’s extra computation.

impl<T: Config> OnInitialize<<T as Config>::BlockNumber> for Pallet<T>

fn on_initialize(n: <T as Config>::BlockNumber) -> Weight

The block is being initialized. Implement to have something happen.

impl<T: Config> OnRuntimeUpgrade for Pallet<T>

fn on_runtime_upgrade() -> Weight

Perform a module upgrade.

fn pre_upgrade() -> Result<(), &'static str>

Execute some pre-checks prior to a runtime upgrade.

fn post_upgrade() -> Result<(), &'static str>

Execute some post-checks after a runtime upgrade.

impl<T: Config> PalletInfoAccess for Pallet<T>

fn index() -> usize

Index of the pallet as configured in the runtime.

fn name() -> &'static str

Name of the pallet as configured in the runtime.

impl<T> PartialEq<Pallet<T>> for Pallet<T>

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<T: Config> StorageInfoTrait for Pallet<T>

fn storage_info() -> Vec<StorageInfo>

impl<T: Config> ValidateUnsigned for Pallet<T>

fn validate_unsigned(
    _source: TransactionSource,
    call: &Self::Call
) -> TransactionValidity

Validate unsigned call to this module.

By default unsigned transactions are disallowed, but implementing the validator here we make sure that some particular calls (the ones produced by offchain worker) are being whitelisted and marked as valid.

type Call = Call<T>

The call to validate

fn pre_dispatch(call: &Self::Call) -> Result<(), TransactionValidityError>

Validate the call right before dispatch.

impl<T> Eq for Pallet<T>