Struct UserMapper

pub struct UserMapper<SA, A = CurrentStorage>
where
    SA: StorageMapperApi,
    A: StorageAddress<SA>,
{ /* private fields */ }

Very widely used mapper, that manages the users of a smart contract. It holds a bi-directional map, from addresses to ids and viceversa. This is so we can easily iterate over all users, using their ids. Also holds the user count in sync. This is also necessary for iteration.

This particular implementation of a user mapper doesn’t contain any additional user data other than address/id.

It also doesn’t allow removing users. Once in, their ids are reserved forever.

Implementations

impl<SA, A> UserMapper<SA, A>

where SA: StorageMapperApi, A: StorageAddress<SA>,

pub fn get_user_id(&self, address: &ManagedAddress<SA>) -> usize

Yields the user id for a given address. Will return 0 if the address is not known to the contract.

pub fn get_user_address(&self, id: usize) -> Option<ManagedAddress<SA>>

Yields the user address for a given id, if the id is valid.

pub fn get_user_address_unchecked(&self, id: usize) -> ManagedAddress<SA>

Yields the user address for a given id. Will cause a deserialization error if the id is invalid.

pub fn get_user_address_or_zero(&self, id: usize) -> ManagedAddress<SA>

Yields the user address for a given id, if the id is valid. Otherwise returns the zero address (0x000…)

pub fn get_user_count(&self) -> usize

Number of users.

pub fn get_all_addresses(&self) -> ManagedVec<SA, ManagedAddress<SA>>

Loads all addresses from storage and places them in a ManagedVec. Can easily consume a lot of gas.

impl<SA> UserMapper<SA, CurrentStorage>

where SA: StorageMapperApi,

pub fn get_or_create_users<AddressIter, F>( &self, address_iter: AddressIter, user_id_lambda: F, )

where AddressIter: Iterator<Item = ManagedAddress<SA>>, F: FnMut(usize, bool),

Tries to insert a number of addresses. Calls a lambda function for each, with the new user id and whether of nor the user was already present.

pub fn get_or_create_user(&self, address: &ManagedAddress<SA>) -> usize

Yields the user id for a given address, or creates a new user id if there isn’t one. Will safely keep the user count in sync.

Trait Implementations

impl<SA> StorageMapper<SA> for UserMapper<SA>

where SA: StorageMapperApi,

fn new(base_key: StorageKey<SA>) -> Self

Will be called automatically by the #[storage_mapper] annotation generated code.

impl<SA> StorageMapperFromAddress<SA> for UserMapper<SA, ManagedAddress<SA>>

where SA: StorageMapperApi,

fn new_from_address( address: ManagedAddress<SA>, base_key: StorageKey<SA>, ) -> Self

Will be called automatically by the #[storage_mapper_from_address] annotation generated code.

impl<SA> TopEncodeMulti for UserMapper<SA, CurrentStorage>

where SA: StorageMapperApi,

Behaves like a MultiResultVec

when an endpoint result, and lists all users addresses.

fn multi_encode_or_handle_err<O, H>( &self, output: &mut O, h: H, ) -> Result<(), H::HandledErr>

where O: TopEncodeMultiOutput, H: EncodeErrorHandler,

Version of top_encode that can handle errors as soon as they occur. For instance in can exit immediately and make sure that if it returns, it is a success. By not deferring error handling, this can lead to somewhat smaller bytecode.

fn multi_encode<O>(&self, output: &mut O) -> Result<(), EncodeError>

where O: TopEncodeMultiOutput,

Attempt to serialize the value to ouput.

impl<SA> TypeAbi for UserMapper<SA, CurrentStorage>

where SA: StorageMapperApi,

Behaves like a MultiResultVec when an endpoint result.

type Unmanaged = UserMapper<SA>

fn type_name() -> TypeName

fn type_name_rust() -> TypeName

fn type_names() -> TypeNames

fn provide_type_descriptions<TDC: TypeDescriptionContainer>( accumulator: &mut TDC, )

A type can provide more than its own name. For instance, a struct can also provide the descriptions of the type of its fields. TypeAbi doesn’t care for the exact accumulator type, which is abstracted by the TypeDescriptionContainer trait.

impl<SA> TypeAbiFrom<UserMapper<SA>> for MultiValueEncoded<SA, ManagedAddress<SA>>

where SA: StorageMapperApi,

impl<SA> TypeAbiFrom<UserMapper<SA>> for UserMapper<SA, CurrentStorage>

where SA: StorageMapperApi,