Module polkadot_sdk_frame::traits

All traits often used in FRAME pallets.

Note that types implementing these traits can also be found in this module.

Modules

• defensive_prelude
  Prelude module for all defensive traits to be imported at once.
• dynamic_params
  Types and traits for dynamic parameters.
• schedule
  Traits and associated utilities for scheduling dispatchables in FRAME.
• tasks
  Contains the Task trait, which defines a general-purpose way for defining and executing service work, and supporting types.
• tokens
  Traits for working with tokens and their associated datastructures.

Macros

• parameter_types
  Create new implementations of the Get trait.

Structs

• AccountIdLookup
  A lookup implementation returning the AccountId from a MultiAddress.
• ActiveIssuanceOf
  A non-const Get implementation parameterised by a Currency impl which provides the result of active_issuance.
• AppendZerosInput
  Input that adds infinite number of zero after wrapped input.
• AsContains
  Adapter struct for turning an OrderedMembership impl into a Contains impl.
• AsEnsureOriginWithArg
• Backing
  Some amount of backing from a group. The precise definition of what it means to “back” something is left flexible.
• BadOrigin
  An error type that indicates that the origin is invalid.
• BlakeTwo256
  Blake2-256 Hash implementation.
• CallMetadata
  The function and pallet name of the Call.
• CheckedReduceBy
  A TryMorph implementation to reduce a scalar by a particular amount, checking for underflow.
• ClassCountOf
• ClearFilterGuard
  Guard type for clearing all pushed constraints from a FilterStack and reinstating them when dropped.
• ConstBool
  Const getter for a basic type.
• ConstI8
  Const getter for a basic type.
• ConstI16
  Const getter for a basic type.
• ConstI32
  Const getter for a basic type.
• ConstI64
  Const getter for a basic type.
• ConstI128
  Const getter for a basic type.
• ConstU8
  Const getter for a basic type.
• ConstU16
  Const getter for a basic type.
• ConstU32
  Const getter for a basic type.
• ConstU64
  Const getter for a basic type.
• ConstU128
  Const getter for a basic type.
• ConvertInto
  A structure that performs standard conversion using the standard Rust conversion traits.
• ConvertToValue
  Adapter which turns a Get implementation into a Convert implementation which always returns in the same value no matter the input.
• CrateVersion
  The version of a crate.
• EitherOf
  “OR gate” implementation of EnsureOrigin, Success type for both L and R must be equal.
• EitherOfDiverse
  “OR gate” implementation of EnsureOrigin allowing for different Success types for L and R, with them combined using an Either type.
• EnqueueWithOrigin
  Adapter type to transform an EnqueueMessage with an origin into a HandleMessage impl.
• EnsureOriginEqualOrHigherPrivilege
  EnsureOrigin implementation that checks that an origin has equal or higher privilege compared to the expected Origin.
• EqualPrivilegeOnly
  Implementation of PrivilegeCmp that only checks for equal origins.
• Equals
  An implementation of Contains which contains only equal members to T.
• EverythingBut
  A Contains implementation that contains everything except the values in Exclude.
• FilterStackGuard
  Guard type for pushing a constraint to a FilterStack and popping when dropped.
• Footprint
  The resource footprint of a bunch of blobs. We assume only the number of blobs and their total size in bytes matter.
• FromContains
  A ContainsPair implementation that has a Contains implementation for each member of the pair.
• FromContainsPair
  Converter struct to use a ContainsPair implementation for a Contains bound.
• GetDefault
  Implement Get by returning Default for any type that implements Default.
• Identity
  A structure that performs identity conversion.
• IdentityLookup
  A lookup implementation returning the input value.
• InsideBoth
  A Contains implementation which contains all members of These which are also members of Those.
• IsInVec
  Trivial utility for implementing Contains/OrderedMembership with a Vec.
• Keccak256
  Keccak-256 Hash implementation.
• LinearStoragePrice
  A storage price that increases linearly with the number of elements and their size.
• LookupError
  An error that indicates that a lookup failed.
• MapSuccess
  A derivative EnsureOrigin implementation. It mutates the Success result of an Original implementation with a given Mutator.
• MorphInto
  Implementation of Morph which converts between types using Into.
• MorphWithUpperLimit
  A TryMorph implementation to enforce an upper limit for a result of the outer morphed type.
• NeverEnsureOrigin
  EnsureOrigin implementation that always fails.
• NoStorageVersionSet
  Special marker struct used when storage_version is not defined for a pallet.
• NoopServiceQueues
  Services queues by doing nothing.
• PalletInfoData
  Information regarding an instance of a pallet.
• PhantomData
  Zero-sized type used to mark things that “act like” they own a T.
• QueueFootprint
  The resource footprint of a queue.
• ReduceBy
  Mutator which reduces a scalar by a particular amount.
• Replace
  Morpher to disregard the source value and replace with another.
• ReplaceWithDefault
  Morpher to disregard the source value and replace with the default of V.
• SignedExtensionMetadata
  Information about a SignedExtension for the runtime metadata.
• StorageInfo
  Metadata about storage from the runtime.
• StorageMapShim
  A shim for placing around a storage item in order to use it as a StoredValue. Ideally this wouldn’t be needed as StorageValues should blanket implement StoredValues, however this would break the ability to have custom impls of StoredValue. The other workaround is to implement it directly in the macro.
• StorageVersion
  The storage version of a pallet.
• TakeFirst
  Implementation of Morph to retrieve just the first element of a tuple.
• TheseExcept
  A Contains implementation that contains all members of These excepting any members in Except.
• TotalIssuanceOf
  A non-const Get implementation parameterised by a Currency impl which provides the result of total_issuance.
• TrackedStorageKey
  Storage key with read/write tracking information.
• TrailingZeroInput
  Input that adds infinite number of zero after wrapped input.
• TransformOrigin
  Transform the origin of an EnqueueMessage via C::convert.
• TryConvertInto
  A structure that performs standard conversion using the standard Rust conversion traits.
• TryDecodeEntireStorageError
  A value could not be decoded.
• TryMapSuccess
  A derivative EnsureOrigin implementation. It mutates the Success result of an Original implementation with a given Mutator, allowing the possibility of an error to be returned from the mutator.
• TryMorphInto
  Implementation of TryMorph which attempts to convert between types using TryInto.
• TryWithMorphedArg
• VariantCountOf
  Adapter for Get<u32> to access VARIANT_COUNT from trait pub trait VariantCount {.
• WithdrawReasons
  Reasons for moving funds out of an account.
• WrapperKeepOpaque
  A wrapper for any type T which implement encode/decode in a way compatible with Vec<u8>.
• WrapperOpaque
  A wrapper for any type T which implement encode/decode in a way compatible with Vec<u8>.

Enums

• BalanceStatus
  Status of funds.
• Everything
  A Contains implementation that contains every value.
• ExecuteOverweightError
  Errors that can happen when attempting to execute an overweight message with ServiceQueues::execute_overweight().
• ExistenceRequirement
  Simple boolean for whether an account needs to be kept in existence.
• Nothing
  A Contains implementation that contains no value.
• PollStatus
• ProcessMessageError
  Errors that can happen when attempting to process a message with ProcessMessage::process_message().
• SafeModeError
  The error type for SafeMode.
• SameOrOther
  Return type used when we need to return one of two items, each of the opposite direction or sign, with one (Same) being of the same type as the self or primary argument of the function that returned it.
• SignedImbalance
  Either a positive or a negative imbalance.
• TransactionPauseError
  The error type for TransactionPause.
• TryStateSelect
  Which state tests to execute.
• UpgradeCheckSelect
  Select which checks should be run when trying a runtime upgrade upgrade.

Constants

• STORAGE_VERSION_STORAGE_KEY_POSTFIX
  The storage key postfix that is used to store the StorageVersion per pallet.

Traits

• AccountIdConversion
  This type can be converted into and possibly from an AccountId (which itself is generic).
• AccountTouch
  Trait for touching/creating an asset account with a deposit taken from a designated depositor specified by the client.
• AppVerify
  Means of signature verification of an application key.
• Applyable
  An “executable” piece of information, used by the standard Substrate Executive in order to enact a piece of extrinsic information by marshalling and dispatching to a named function call.
• AtLeast32Bit
  A meta trait for arithmetic.
• AtLeast32BitUnsigned
  A meta trait for arithmetic. Same as AtLeast32Bit, but also bounded to be unsigned.
• BeforeAllRuntimeMigrations
  Implemented by pallets, allows defining logic to run prior to any OnRuntimeUpgrade logic.
• BlindCheckable
  A “checkable” piece of information, used by the standard Substrate Executive in order to check the validity of a piece of extrinsic information, usually by verifying the signature. Implement for pieces of information that don’t require additional context in order to be checked.
• Block
  Something which fulfills the abstract idea of a Substrate block. It has types for Extrinsic pieces of information as well as a Header.
• BlockIdTo
  Something that can convert a BlockId to a number or a hash.
• BlockNumber
  Super trait with all the attributes for a block number.
• BlockNumberProvider
  Get current block number
• BuildGenesisConfig
  A trait to define the build function of a genesis config for both runtime and pallets.
• CallerTrait
  The trait implemented by the overarching enumeration of the different pallets’ origins. Unlike OriginTrait impls, this does not include any kind of dispatch/call filter. Also, this trait is more flexible in terms of how it can be used: it is a Parameter and Member, so it can be used as dispatchable parameters as well as in storage items.
• ChangeMembers
  Trait for type that can handle incremental changes to a set of account IDs.
• CheckEqual
  Something that can be checked for equality and printed out to a debug channel if bad.
• Checkable
  Extract the digest type for a block. A “checkable” piece of information, used by the standard Substrate Executive in order to check the validity of a piece of extrinsic information, usually by verifying the signature. Implement for pieces of information that require some additional context Context in order to be checked.
• CheckedAdd
  Performs addition that returns None instead of wrapping around on overflow.
• CheckedConversion
  Convenience type to work around the highly unergonomic syntax needed to invoke the functions of overloaded generic traits, in this case TryFrom and TryInto.
• CheckedDiv
  Performs division that returns None instead of panicking on division by zero and instead of wrapping around on underflow and overflow.
• CheckedMul
  Performs multiplication that returns None instead of wrapping around on underflow or overflow.
• CheckedShl
  Performs a left shift that returns None on shifts larger than or equal to the type width.
• CheckedShr
  Performs a right shift that returns None on shifts larger than or equal to the type width.
• CheckedSub
  Performs subtraction that returns None instead of wrapping around on underflow.
• Clear
  Trait for things that can be clear (have no bits set). For numeric types, essentially the same as Zero.
• Consideration
  Some sort of cost taken from account temporarily in order to offset the cost to the chain of holding some data Footprint in state.
• Contains
  A trait for querying whether a type can be said to “contain” a value.
• ContainsLengthBound
  A trait for querying bound for the length of an implementation of Contains
• ContainsPair
  A trait for querying whether a type can be said to “contain” a pair-value.
• Convert
  Infallible conversion trait. Generic over both source and destination types.
• ConvertBack
  Reversing infallible conversion trait. Generic over both source and destination types.
• Currency
  Abstraction over a fungible assets system.
• Defensive
  A trait to handle errors and options when you are really sure that a condition must hold, but not brave enough to expect on it, or a default fallback value makes more sense.
• DefensiveMax
  Defensively calculates the maximum of two values.
• DefensiveMin
  Defensively calculates the minimum of two values.
• DefensiveOption
  Subset of methods similar to Defensive that can only work for a Option.
• DefensiveResult
  Subset of methods similar to Defensive that can only work for a Result.
• DefensiveSaturating
  A variant of Defensive with the same rationale, for the arithmetic operations where in case an infallible operation fails, it saturates.
• DefensiveTruncateFrom
  Construct an object by defensively truncating an input if the TryFrom conversion fails.
• DisabledValidators
  Trait used to check whether a given validator is currently disabled and should not be participating in consensus (e.g. because they equivocated).
• Dispatchable
  A lazy call (module function and argument values) that can be executed via its dispatch method.
• EnqueueMessage
  Can enqueue messages for multiple origins.
• Ensure
• EnsureAdd
  Performs addition that returns ArithmeticError instead of wrapping around on overflow.
• EnsureAddAssign
  Performs self addition that returns ArithmeticError instead of wrapping around on overflow.
• EnsureDiv
  Performs division that returns ArithmeticError instead of wrapping around on overflow.
• EnsureDivAssign
  Performs self division that returns ArithmeticError instead of wrapping around on overflow.
• EnsureFixedPointNumber
  Extends FixedPointNumber with the Ensure family functions.
• EnsureFrom
  Similar to TryFrom but returning an ArithmeticError error.
• EnsureInherentsAreFirst
  A trait to ensure the inherent are before non-inherent in a block.
• EnsureInto
  Similar to TryInto but returning an ArithmeticError error.
• EnsureMul
  Performs multiplication that returns ArithmeticError instead of wrapping around on overflow.
• EnsureMulAssign
  Performs self multiplication that returns ArithmeticError instead of wrapping around on overflow.
• EnsureOp
  Meta trait that supports all immutable arithmetic Ensure* operations
• EnsureOpAssign
  Meta trait that supports all assigned arithmetic Ensure* operations
• EnsureOrigin
  Some sort of check on the origin is performed by this object.
• EnsureOriginWithArg
  Some sort of check on the origin is performed by this object.
• EnsureSub
  Performs subtraction that returns ArithmeticError instead of wrapping around on underflow.
• EnsureSubAssign
  Performs self subtraction that returns ArithmeticError instead of wrapping around on underflow.
• EstimateCallFee
  Something that can estimate the fee of a (frame-based) call.
• EstimateNextNewSession
  Something that can estimate at which block scheduling of the next session will happen (i.e when we will try to fetch new validators).
• EstimateNextSessionRotation
  Something that can estimate at which block the next session rotation will happen (i.e. a new session starts).
• ExecuteBlock
  Something that can execute a given block.
• Extrinsic
  Something that acts like an Extrinsic.
• ExtrinsicCall
  An extrinsic on which we can get access to call.
• ExtrinsicMetadata
  Implementor is an Extrinsic and provides metadata about this extrinsic.
• FilterDeprecated
• FilterStack
  Trait to add a constraint onto the filter.
• FindAuthor
  A trait for finding the author of a block header based on the PreRuntime digests contained within it.
• GenesisBuildDeprecated
  A trait to define the build function of a genesis config, T and I are placeholder for pallet trait and pallet instance.
• Get
  A trait for querying a single value from a type.
• GetBacking
  Retrieve the backing from an object’s ref.
• GetCallIndex
  Gets the function index of the Call.
• GetCallMetadata
  Gets the metadata for the Call - function name and pallet name.
• GetCallName
  Gets the function name of the Call.
• GetNodeBlockType
  A marker trait for something that knows the type of the node block.
• GetRuntimeBlockType
  A marker trait for something that knows the type of the runtime block.
• GetStorageVersion
  Provides information about a pallet’s storage versions.
• HandleLifetime
  A simple, generic one-parameter event notifier/handler.
• HandleMessage
  Handles incoming messages for a single origin.
• Hash
  Abstraction around hashing
• HashOutput
  Super trait with all the attributes for a hashing output.
• Header
  Something which fulfills the abstract idea of a Substrate header. It has types for a Number, a Hash and a Hashing. It provides access to an extrinsics_root, state_root and parent_hash, as well as a digest and a block number.
• Hooks
  The pallet hooks trait. This is merely an umbrella trait for:
• IdentifyAccount
  Some type that is able to be collapsed into an account ID. It is not possible to recreate the original value from the account ID.
• Imbalance
  A trait for a not-quite Linear Type that tracks an imbalance.
• Incrementable
  A trait representing an incrementable type.
• InitializeMembers
  Trait for type that can handle the initialization of account IDs at genesis.
• InspectLockableCurrency
  A inspect interface for a currency whose accounts can have liquidity restrictions.
• Instance
  An instance of a pallet in the storage.
• InstanceFilter
  Simple trait for providing a filter over a reference to some type, given an instance of itself.
• IntegerSquareRoot
  A trait implementing integer square root.
• IntegrityTest
  See Hooks::integrity_test.
• IsInherent
  A trait to check if an extrinsic is an inherent.
• IsMember
  Determine if a MemberId is a valid member.
• IsSubType
  Something that can be checked to be a of sub type T.
• IsType
  Trait to be used when types are exactly same.
• KeyOwnerProofSystem
  Something which can compute and check proofs of a historical key owner and return full identification data of that key owner.
• Lateness
  Trait to be used by block producing consensus engine modules to determine how late the current block is (e.g. in a slot-based proposal mechanism how many slots were skipped since the previous block).
• Lazy
  A lazy value.
• Len
  Anything that can have a ::len() method.
• LockableCurrency
  A currency whose accounts can have liquidity restrictions.
• Locker
  Trait to handle NFT locking mechanism to ensure interactions with the asset can be implemented downstream to extend logic of Uniques/Nfts current functionality.
• Lookup
  Means of changing one type into another in a manner dependent on the source type.
• MaybeConvert
  Fallible conversion trait returning an Option. Generic over both source and destination types.
• MaybeConvertBack
  Reversing fallible conversion trait returning an Option. Generic over both source and destination types.
• MaybeDisplay
  A type that implements Display when in std environment.
• MaybeEquivalence
  Definition for a bi-directional, fallible conversion between two types.
• MaybeFromStr
  A type that implements FromStr when in std environment.
• MaybeHash
  A type that implements Hash when in std environment.
• MaybeSerialize
  A type that implements Serialize when in std environment or serde feature is activated.
• MaybeSerializeDeserialize
  A type that implements Serialize, DeserializeOwned and Debug when in std environment or serde feature is activated.
• Member
  A type that can be used in runtime structures.
• Morph
  Extensible conversion trait. Generic over only source type, with destination type being associated.
• NamedReservableCurrency
• OffchainWorker
  Off-chain computation trait.
• OnFinalize
  See Hooks::on_finalize.
• OnGenesis
  A trait that will be called at genesis.
• OnIdle
  See Hooks::on_idle.
• OnInitialize
  See Hooks::on_initialize.
• OnKilledAccount
  The account with the given id was reaped.
• OnNewAccount
  Handler for when a new account has been created.
• OnPoll
  Periodically executes logic. Is not guaranteed to run within a specific timeframe and should only be used on logic that has no deadline.
• OnRuntimeUpgrade
  See Hooks::on_runtime_upgrade.
• OnTimestampSet
  A trait which is called when the timestamp is set in the runtime.
• OnUnbalanced
  Handler for when some currency “account” decreased in balance for some reason.
• One
  Defines a multiplicative identity element for Self.
• OneSessionHandler
  A session handler for specific key type.
• OpaqueKeys
  Opaque data type that may be destructured into a series of raw byte slices (which represent individual keys).
• OriginTrait
  Methods available on frame_system::Config::RuntimeOrigin.
• PalletError
  Trait indicating that the implementing type is going to be included as a field in a variant of the #[pallet::error] enum type.
• PalletInfo
  Provides information about the pallet itself and its setup in the runtime.
• PalletInfoAccess
  Provides information about the pallet itself and its setup in the runtime.
• PalletsInfoAccess
  Provide information about a bunch of pallets.
• PartialStorageInfoTrait
  Similar to StorageInfoTrait, a trait to give partial information about storage.
• Polling
• PostInherents
  Provides a callback to execute logic after the all inherents.
• PostTransactions
  Provides a callback to execute logic before the all transactions.
• PreInherents
  Provides a callback to execute logic before the all inherents.
• PreimageProvider
  A interface for looking up preimages from their hash on chain.
• PreimageRecipient
  A interface for managing preimages to hashes on chain.
• Printable
  Trait for things which can be printed from the runtime.
• PrivilegeCmp
  Something that can compare privileges of two origins.
• ProcessMessage
  Can process messages from a specific origin.
• QueryPreimage
  A interface for looking up preimages from their hash on chain.
• QueuePausedQuery
  Provides information on paused queues.
• Randomness
  A trait that is able to provide randomness.
• RankedMembers
  Ranked membership data structure.
• RankedMembersSwapHandler
  Handler that can deal with the swap of two members.
• ReservableCurrency
  A currency where funds can be reserved from the user.
• SafeMode
  Can put the runtime into a safe mode.
• SafeModeNotify
  A trait to notify when the runtime enters or exits safe mode.
• SaturatedConversion
  Convenience type to work around the highly unergonomic syntax needed to invoke the functions of overloaded generic traits, in this case SaturatedFrom and SaturatedInto.
• Saturating
  Saturating arithmetic operations, returning maximum or minimum values instead of overflowing.
• Scale
  Multiply and divide by a number that isn’t necessarily the same type. Basically just the same as Mul and Div except it can be used for all basic numeric types.
• ServiceQueues
  Can service queues and execute overweight messages.
• SignaturePayload
  Something that acts like a SignaturePayload of an Extrinsic.
• SignedExtension
  Means by which a transaction may be extended. This type embodies both the data and the logic that should be additionally associated with the transaction. It should be plain old data.
• SimpleBitOps
  A meta trait for all bit ops.
• SortedMembers
  A trait for a set which can enumerate its members in order.
• StaticLookup
  Means of changing one type into another in a manner dependent on the source type. This variant is different to Lookup in that it doesn’t (can cannot) require any context.
• StorageInfoTrait
  A trait to give information about storage.
• StorageInstance
  An instance of a storage in a pallet.
• StorePreimage
  A interface for managing preimages to hashes on chain.
• StoredMap
  An abstraction of a value stored within storage, but possibly as part of a larger composite item.
• Task
  A general-purpose trait which defines a type of service work (i.e., work to performed by an off-chain worker) including methods for enumerating, validating, indexing, and running tasks of this type.
• Time
• TransactionPause
  Can pause specific transactions from being processed.
• TryCollect
  Try and collect into a collection C.
• TryConvert
  Fallible conversion trait which returns the argument in the case of being unable to convert. Generic over both source and destination types.
• TryConvertBack
  Reversing fallible conversion trait which returns the argument in the case of being unable to convert back. Generic over both source and destination types.
• TryDecodeEntireStorage
  Decode the entire data under the given storage type.
• TryDrop
  A type for which some values make sense to be able to drop without further consideration.
• TryMorph
  Extensible conversion trait. Generic over only source type, with destination type being associated.
• TryState
  Execute some checks to ensure the internal state of a pallet is consistent.
• TypedGet
  A trait for querying a single value from a type defined in the trait.
• UncheckedOnRuntimeUpgrade
  This trait is intended for use within VersionedMigration to execute storage migrations without automatic version checks. Implementations should ensure migration logic is safe and idempotent.
• UnfilteredDispatchable
  Type that can be dispatched with an origin but without checking the origin filter.
• UniqueSaturatedFrom
  Just like From except that if the source value is too big to fit into the destination type then it’ll saturate the destination.
• UniqueSaturatedInto
  Just like Into except that if the source value is too big to fit into the destination type then it’ll saturate the destination.
• UnixTime
  Trait to deal with unix time.
• ValidateUnsigned
  Provide validation for unsigned extrinsics.
• ValidatorRegistration
  Implementors of this trait provide information about whether or not some validator has been registered with them. The Session module is an implementor.
• ValidatorSet
  A trait for online node inspection in a session.
• ValidatorSetWithIdentification
  ValidatorSet combined with an identification.
• VariantCount
  Trait to get the number of variants in any enum.
• Verify
  Means of signature verification.
• VerifySeal
  A trait for verifying the seal of a header and returning the author.
• VestingSchedule
  A vesting schedule over a currency. This allows a particular currency to have vesting limits applied to it.
• VoteTally
• WhitelistedStorageKeys
  Allows a pallet to specify storage keys to whitelist during benchmarking. This means those keys will be excluded from the benchmarking performance calculation.
• Zero
  Defines an additive identity element for Self.

Functions

• checked_pow
  Raises a value to the power of exp, returning None if an overflow occurred.
• ensure_pow
  Raises a value to the power of exp, returning ArithmeticError if an overflow occurred.

Type Aliases

• AllowAllDeprecated
• BoundedInline
• DenyAllDeprecated
• DispatchInfoOf
  Shortcut to reference the Info type of a Dispatchable.
• EnsureOneOfDeprecated
  “OR gate” implementation of EnsureOrigin allowing for different Success types for L and R, with them combined using an Either type.
• FetchResult
• HashingFor
  Extract the hashing type for a block.
• LockIdentifier
  An identifier for a lock. Used for disambiguating different locks so that they can be individually replaced or removed.
• NumberFor
  Extract the number type for a block.
• PostDispatchInfoOf
  Shortcut to reference the PostInfo type of a Dispatchable.