Struct Event 

pub struct Event<B, M, D> {
    pub filter: Filter,
    /* private fields */
}

Helper for managing the event filter before querying or streaming its logs

Fields

filter: Filter

The event filter’s state

Implementations

impl<B, M, D> Event<B, M, D>

where B: Borrow<M>, M: Middleware, D: EthLogDecode,

pub fn from_block<T>(self, block: T) -> Event<B, M, D>

where T: Into<BlockNumber>,

Sets the filter’s from block

pub fn to_block<T>(self, block: T) -> Event<B, M, D>

where T: Into<BlockNumber>,

Sets the filter’s to block

pub fn at_block_hash<T>(self, hash: T) -> Event<B, M, D>

where T: Into<H256>,

Sets the filter’s blockHash. Setting this will override previously set from_block and to_block fields.

pub fn topic0<T>(self, topic: T) -> Event<B, M, D>

where T: Into<ValueOrArray<Option<H256>>>,

Sets the filter’s 0th topic (typically the event name for non-anonymous events)

pub fn topic1<T>(self, topic: T) -> Event<B, M, D>

where T: Into<ValueOrArray<Option<H256>>>,

Sets the filter’s 1st topic

pub fn topic2<T>(self, topic: T) -> Event<B, M, D>

where T: Into<ValueOrArray<Option<H256>>>,

Sets the filter’s 2nd topic

pub fn topic3<T>(self, topic: T) -> Event<B, M, D>

where T: Into<ValueOrArray<Option<H256>>>,

Sets the filter’s 3rd topic

pub fn address(self, address: ValueOrArray<H160>) -> Event<B, M, D>

Sets the filter’s address.

impl<B, M, D> Event<B, M, D>

where B: Borrow<M>, M: Middleware, D: EthLogDecode,

pub async fn stream( &self, ) -> Result<EventStream<'_, FilterWatcher<'_, <M as Middleware>::Provider, Log>, D, ContractError<M>>, ContractError<M>>

Turns this event filter into Stream that yields decoded events.

This will first install a new logs filter via eth_newFilter using the configured filter object. See also FilterWatcher.

Once the filter is created, this will periodically call eth_getFilterChanges to get the newest logs and decode them.

Note: Compared to Self::subscribe, which is only available on PubsubClients, such as Websocket, this is a poll-based subscription, as the node does not notify us when a new matching log is available, instead we have to actively ask for new logs using additional RPC requests, and this is done on an interval basis.

Example

// The event we want to get
#[derive(Clone, Debug, EthEvent)]
pub struct Approval {
    #[ethevent(indexed)]
    pub token_owner: Address,
    #[ethevent(indexed)]
    pub spender: Address,
    pub tokens: U256,
}

let ev = contract.event::<Approval>().from_block(1337).to_block(2000);
let mut event_stream = ev.stream().await.unwrap();

 while let Some(Ok(approval)) = event_stream.next().await {
     let Approval{token_owner,spender,tokens} = approval;
}

pub async fn stream_with_meta( &self, ) -> Result<EventStream<'_, FilterWatcher<'_, <M as Middleware>::Provider, Log>, (D, LogMeta), ContractError<M>>, ContractError<M>>

As Self::stream, but does not discard Log metadata.

impl<B, M, D> Event<B, M, D>

where B: Borrow<M>, M: Middleware, <M as Middleware>::Provider: PubsubClient, D: EthLogDecode,

pub async fn subscribe( &self, ) -> Result<EventStream<'_, SubscriptionStream<'_, <M as Middleware>::Provider, Log>, D, ContractError<M>>, ContractError<M>>

Returns a subscription for the event

See also Self::stream().

pub async fn subscribe_with_meta( &self, ) -> Result<EventStream<'_, SubscriptionStream<'_, <M as Middleware>::Provider, Log>, (D, LogMeta), ContractError<M>>, ContractError<M>>

As Self::subscribe, but includes event metadata

impl<B, M, D> Event<B, M, D>

where B: Borrow<M>, M: Middleware, D: EthLogDecode,

pub async fn query(&self) -> Result<Vec<D>, ContractError<M>>

Queries the blockchain for the selected filter and returns a vector of matching event logs

pub async fn query_with_meta( &self, ) -> Result<Vec<(D, LogMeta)>, ContractError<M>>

Queries the blockchain for the selected filter and returns a vector of logs along with their metadata

Trait Implementations

impl<B, M, D> Debug for Event<B, M, D>

where B: Debug, M: Debug, D: Debug,

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

Formats the value using the given formatter.