Fix deserialization failure of blockscout contract_source response

src/contract.rs

@@ -1,5 +1,5 @@
 use crate::{
-    serde_helpers::deserialize_stringified_u64,
+    serde_helpers::{deserialize_stringified_u64, deserialize_stringified_bool_or_u64},
     source_tree::{SourceTree, SourceTreeEntry},
     utils::{deserialize_address_opt, deserialize_source_code},
     Client, EtherscanError, Response, Result,
@@ -128,14 +128,15 @@ pub struct Metadata {
     pub compiler_version: String,
 
     /// Whether the optimizer was used. This value should only be 0 or 1.
-    #[serde(deserialize_with = "deserialize_stringified_u64")]
+    #[serde(deserialize_with = "deserialize_stringified_bool_or_u64")]
     pub optimization_used: u64,
 
     /// The number of optimizations performed.
-    #[serde(deserialize_with = "deserialize_stringified_u64")]
+    #[serde(deserialize_with = "deserialize_stringified_u64", alias="OptimizationRuns")]
     pub runs: u64,
 
     /// The constructor arguments the contract was deployed with.
+    #[serde(default)]
     pub constructor_arguments: Bytes,
 
     /// The version of the EVM the contract was deployed in. Can be either a variant of EvmVersion
@@ -144,13 +145,15 @@ pub struct Metadata {
     pub evm_version: String,
 
     // ?
+    #[serde(default)]
     pub library: String,
 
     /// The license of the contract.
+    #[serde(default)]
     pub license_type: String,
 
     /// Whether this contract is a proxy. This value should only be 0 or 1.
-    #[serde(deserialize_with = "deserialize_stringified_u64")]
+    #[serde(deserialize_with = "deserialize_stringified_bool_or_u64", alias="IsProxy")]
     pub proxy: u64,
 
     /// If this contract is a proxy, the address of its implementation.
@@ -162,6 +165,7 @@ pub struct Metadata {
     pub implementation: Option<Address>,
 
     /// The swarm source of the contract.
+    #[serde(default)]
     pub swarm_source: String,
 }
 

src/serde_helpers.rs

@@ -46,6 +46,34 @@ impl TryFrom<StringifiedNumeric> for U64 {
     }
 }
 
+
+#[derive(Deserialize)]
+#[serde(untagged)]
+enum BoolOrU64 {
+    #[serde(deserialize_with = "deserialize_stringified_u64")]
+    U64(u64),
+    Bool(String),
+}
+
+
+/// Supports parsing either a u64 or a boolean (which will then be converted to u64) 
+/// Implemented to binary fields such as "OptimizationUsed" which are formatted either as 0/1 or
+/// "true/"false" by different block explorers (e.g. etherscan vs blockscout)
+pub fn deserialize_stringified_bool_or_u64<'de, D>(deserializer: D) -> Result<u64, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let num = BoolOrU64::deserialize(deserializer)?;
+    match num {
+        BoolOrU64::Bool(b) => {
+            let b = b.parse::<bool>().map_err(serde::de::Error::custom)?;
+            let u = if b { 1 } else { 0 };
+            Ok(u)
+        }
+        BoolOrU64::U64(u) => Ok(u),
+    }
+}
+
 /// Supports parsing u64
 ///
 /// See <https://github.com/gakonst/ethers-rs/issues/1507>