xxx: Backup

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

examples/examples/tx_basic_light_client.rs

@@ -98,23 +98,23 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             let mut sub = api
                 .rpc()
                 .chainhead_unstable_body(sub_id.clone(), hash)
-                .await?
-                .take(5);
+                .await?;
 
-            while let Some(event) = sub.next().await {
+            if let Some(event) = sub.next().await {
                 let event = event?;
-
                 println!("  chainHead_body event: {event:?}");
             }
 
             // Fetch the block's header.
-            // let header = api
-            //     .rpc()
-            //     .chainhead_unstable_header(sub_id.clone(), hash)
-            //     .await?;
-            // let header = header.expect("RPC must have this header in memory; qed");
-
-            // println!("  chainHead_header: {header}");
+            let header = api
+                .rpc()
+                .chainhead_unstable_header(sub_id.clone(), hash)
+                .await?;
+            if let Some(header) = header {
+                println!("  chainHead_header: {header}");
+            } else {
+                println!("  chainHead_header: Header not in memory for {hash}");
+            }
 
             // Make a storage query.
             let account_id: AccountId32 = AccountKeyring::Alice.to_account_id().into();
@@ -124,12 +124,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             let mut sub = api
                 .rpc()
                 .chainhead_unstable_storage(sub_id.clone(), hash, &addr_bytes, None)
-                .await?
-                .take(5);
+                .await?;
 
-            while let Some(event) = sub.next().await {
+            if let Some(event) = sub.next().await {
                 let event = event?;
-
                 println!("  chainHead_storage event: {event:?}");
             }
         }

subxt/src/rpc/types.rs

@@ -507,15 +507,46 @@ pub enum FollowEvent<Hash> {
 /// The result of a chain head method.
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[cfg(feature = "experimental-light-client")]
+#[serde(try_from = "LightClientChainHeadResult<T>")]
 pub struct ChainHeadResult<T> {
     /// Result of the method.
     #[cfg(not(feature = "experimental-light-client"))]
     pub result: T,
     /// Result of the method.
+    ///
+    /// # Note
+    ///
+    /// `chainHead_body` returns a vector of values, while
+    /// `chainHead_storage` returns just one plain element.
     #[cfg(feature = "experimental-light-client")]
     pub value: Vec<T>,
 }
 
+/// The result of a chain head method.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
+#[serde(rename_all = "camelCase")]
+#[cfg(feature = "experimental-light-client")]
+pub struct LightClientChainHeadResult<T> {
+    /// Result of the method.
+    ///
+    /// # Note
+    ///
+    /// `chainHead_body` returns a vector of values, while
+    /// `chainHead_storage` returns just one plain element.
+    pub value: T,
+}
+
+impl<T> TryFrom<LightClientChainHeadResult<T>> for ChainHeadResult<T> {
+    type Error = &'static str;
+
+    fn try_from(light: LightClientChainHeadResult<T>) -> Result<Self, &'static str> {
+        Ok(Self {
+            value: vec![light.value],
+        })
+    }
+}
+
 /// The event generated by the body / call / storage methods.
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
 #[serde(rename_all = "camelCase")]