contract: simplify lifetimes

ethers-contract/src/contract.rs

@@ -44,18 +44,15 @@ where
         }
     }
 
-    /// Returns an `Event` builder for the provided event name. If there are
+    /// Returns an `Event` builder for the provided event name.
-    /// multiple functions with the same name due to overloading, consider using
+    pub fn event<D: Detokenize>(&self, name: &str) -> Result<Event<P, D>, Error> {
-    /// the `method_hash` method instead, since this will use the first match.
-    pub fn event<'b, D: Detokenize>(&'a self, name: &str) -> Result<Event<'a, 'b, P, D>, Error>
-    where
-        'a: 'b,
-    {
         // get the event's full name
         let event = self.abi.event(name)?;
         Ok(Event {
             provider: &self.client.provider(),
-            filter: Filter::new().event(&event.abi_signature()),
+            filter: Filter::new()
+                .event(&event.abi_signature())
+                .address(self.address),
             event: &event,
             datatype: PhantomData,
         })
@@ -113,14 +110,6 @@ where
         })
     }
 
-    pub fn address(&self) -> Address {
-        self.address
-    }
-
-    pub fn abi(&self) -> &Abi {
-        &self.abi
-    }
-
     /// Returns a new contract instance at `address`.
     ///
     /// Clones `self` internally
@@ -138,6 +127,21 @@ where
         this.client = client;
         this
     }
+
+    /// Returns the contract's address
+    pub fn address(&self) -> Address {
+        self.address
+    }
+
+    /// Returns a reference to the contract's ABI
+    pub fn abi(&self) -> &Abi {
+        &self.abi
+    }
+
+    /// Returns a reference to the contract's client
+    pub fn client(&self) -> &Client<P, S> {
+        &self.client
+    }
 }
 
 /// Utility function for creating a mapping between a unique signature and a

ethers-contract/src/event.rs

@@ -4,12 +4,12 @@ use ethers_providers::{JsonRpcClient, Provider};
 
 use ethers_core::{
     abi::{Detokenize, Event as AbiEvent, RawLog},
-    types::{BlockNumber, Filter, ValueOrArray, H256},
+    types::{BlockNumber, Filter, Log, ValueOrArray, H256},
 };
 
 use std::{collections::HashMap, marker::PhantomData};
 
-pub struct Event<'a, 'b, P, D> {
+pub struct Event<'a: 'b, 'b, P, D> {
     pub filter: Filter,
     pub(crate) provider: &'a Provider<P>,
     pub(crate) event: &'b AbiEvent,
@@ -17,7 +17,7 @@ pub struct Event<'a, 'b, P, D> {
 }
 
 // TODO: Improve these functions
-impl<'a, 'b, P, D: Detokenize> Event<'a, 'b, P, D> {
+impl<P, D: Detokenize> Event<'_, '_, P, D> {
     #[allow(clippy::wrong_self_convention)]
     pub fn from_block<T: Into<BlockNumber>>(mut self, block: T) -> Self {
         self.filter.from_block = Some(block.into());
@@ -39,28 +39,50 @@ impl<'a, 'b, P, D: Detokenize> Event<'a, 'b, P, D> {
         self.filter.topics[1] = Some(topic.into());
         self
     }
+
+    pub fn topic2<T: Into<ValueOrArray<H256>>>(mut self, topic: T) -> Self {
+        self.filter.topics[2] = Some(topic.into());
+        self
     }
 
-impl<'a, 'b, P, D> Event<'a, 'b, P, D>
+    pub fn topic3<T: Into<ValueOrArray<H256>>>(mut self, topic: T) -> Self {
+        self.filter.topics[3] = Some(topic.into());
+        self
+    }
+}
+
+impl<P, D> Event<'_, '_, P, D>
 where
     P: JsonRpcClient,
     D: Detokenize + Clone,
 {
     /// Queries the blockchain for the selected filter and returns a vector of matching
     /// event logs
-    pub async fn query(self) -> Result<Vec<D>, ContractError> {
+    pub async fn query(&self) -> Result<Vec<D>, ContractError> {
-        Ok(self.query_with_hashes().await?.values().cloned().collect())
+        let logs = self.provider.get_logs(&self.filter).await?;
+        let events = logs
+            .into_iter()
+            .map(|log| self.parse_log(log))
+            .collect::<Result<Vec<_>, ContractError>>()?;
+        Ok(events)
     }
 
-    /// Queries the blockchain for the selected filter and returns a vector of matching
+    /// Queries the blockchain for the selected filter and returns a hashmap of
-    /// event logs
+    /// txhash -> logs
-    pub async fn query_with_hashes(self) -> Result<HashMap<H256, D>, ContractError> {
+    pub async fn query_with_hashes(&self) -> Result<HashMap<H256, D>, ContractError> {
-        // get the logs
         let logs = self.provider.get_logs(&self.filter).await?;
-
         let events = logs
             .into_iter()
             .map(|log| {
+                let tx_hash = log.transaction_hash.expect("should have tx hash");
+                let event = self.parse_log(log)?;
+                Ok((tx_hash, event))
+            })
+            .collect::<Result<_, ContractError>>()?;
+        Ok(events)
+    }
+
+    fn parse_log(&self, log: Log) -> Result<D, ContractError> {
         // ethabi parses the unindexed and indexed logs together to a
         // vector of tokens
         let tokens = self
@@ -73,16 +95,8 @@ where
             .into_iter()
             .map(|param| param.value)
             .collect::<Vec<_>>();
-
         // convert the tokens to the requested datatype
-                Ok::<_, ContractError>((
+        Ok(D::from_tokens(tokens)?)
-                    log.transaction_hash.expect("should have tx hash"),
-                    D::from_tokens(tokens)?,
-                ))
-            })
-            .collect::<Result<HashMap<H256, D>, _>>()?;
-
-        Ok(events)
     }
 
     // TODO: Add filter watchers

ethers-contract/tests/contract.rs

@@ -1,5 +1,6 @@
 use ethers_contract::ContractFactory;
 use ethers_core::{
+    abi::{Detokenize, InvalidOutputType, Token},
     types::{Address, H256},
     utils::{GanacheBuilder, Solc},
 };
@@ -95,4 +96,48 @@ async fn deploy_and_call_contract() {
         .unwrap();
     assert_eq!(last_sender.clone().call().await.unwrap(), client.address());
     assert_eq!(get_value.clone().call().await.unwrap(), "hi2");
+
+    // and we can fetch the events
+    let logs: Vec<ValueChanged> = contract
+        .event("ValueChanged")
+        .unwrap()
+        .from_block(0u64)
+        .query()
+        .await
+        .unwrap();
+    assert_eq!(logs[0].new_value, "initial value");
+    assert_eq!(logs[1].new_value, "hi");
+    assert_eq!(logs[2].new_value, "hi2");
+
+    let logs: Vec<ValueChanged> = contract2
+        .event("ValueChanged")
+        .unwrap()
+        .from_block(0u64)
+        .query()
+        .await
+        .unwrap();
+    assert_eq!(logs[0].new_value, "initial value");
+    assert_eq!(logs.len(), 1);
+}
+
+// Note: We also provide the `abigen` macro for generating these bindings automatically
+#[derive(Clone, Debug)]
+struct ValueChanged {
+    author: Address,
+    old_value: String,
+    new_value: String,
+}
+
+impl Detokenize for ValueChanged {
+    fn from_tokens(tokens: Vec<Token>) -> Result<ValueChanged, InvalidOutputType> {
+        let author: Address = tokens[0].clone().to_address().unwrap();
+        let old_value = tokens[1].clone().to_string().unwrap();
+        let new_value = tokens[2].clone().to_string().unwrap();
+
+        Ok(Self {
+            author,
+            old_value,
+            new_value,
+        })
+    }
 }