Generate runtime API from metadata

codegen/src/api/storage.rs

@@ -159,6 +159,7 @@ fn generate_storage_entry_fns(
     let pallet_name = &pallet.name;
     let storage_name = &storage_entry.name;
     let fn_name = format_ident!("{}", storage_entry.name.to_snake_case());
+    let fn_name_iter = format_ident!("{}_iter", fn_name);
     let storage_entry_ty = match storage_entry.ty {
         StorageEntryType::Plain(ref ty) => ty,
         StorageEntryType::Map { ref value, .. } => value,
@@ -189,10 +190,23 @@ fn generate_storage_entry_fns(
         }
     };
 
+    let client_iter_fn = if matches!(storage_entry.ty, StorageEntryType::Map { .. }) {
+        quote! (
+            pub async fn #fn_name_iter(
+                &self,
+                hash: ::core::option::Option<T::Hash>,
+            ) -> ::core::result::Result<::subxt::KeyIter<'a, T, #entry_struct_ident>, ::subxt::Error> {
+                self.client.storage().iter(hash).await
+            }
+        )
+    } else {
+        quote! ()
+    };
+
     let key_args = fields
         .iter()
         .map(|(field_name, field_type)| quote!( #field_name: #field_type )); // todo: [AJ] borrow non build-inf types?
-    let client_fn = quote! {
+    let client_fns = quote! {
         pub async fn #fn_name(
             &self,
             #( #key_args, )*
@@ -201,7 +215,9 @@ fn generate_storage_entry_fns(
             let entry = #constructor;
             self.client.storage().#fetch(&entry, hash).await
         }
+
+        #client_iter_fn
     };
 
-    (storage_entry_type, client_fn)
+    (storage_entry_type, client_fns)
 }

examples/fetch_all_accounts.rs

@@ -14,20 +14,35 @@
 // You should have received a copy of the GNU General Public License
 // along with subxt.  If not, see <http://www.gnu.org/licenses/>.
 
-use subxt::{
-    system::AccountStoreExt,
-    ClientBuilder,
-    DefaultNodeRuntime,
-};
+//! To run this example, a local polkadot node should be running.
+//!
+//! E.g.
+//! ```bash
+//! curl "https://github.com/paritytech/polkadot/releases/download/v0.9.11/polkadot" --output /usr/local/bin/polkadot --location
+//! polkadot --dev --tmp
+//! ```
+
+use subxt::ClientBuilder;
+
+#[subxt::subxt(runtime_metadata_path = "examples/polkadot_metadata.scale")]
+pub mod polkadot {}
 
 #[async_std::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     env_logger::init();
 
-    let client = ClientBuilder::<DefaultNodeRuntime>::new().build().await?;
-    let mut iter = client.account_iter(None).await?;
+    let api = ClientBuilder::new()
+        .build()
+        .await?
+        .to_runtime_api::<polkadot::RuntimeApi<polkadot::DefaultConfig>>();
+
+    let mut iter = api
+        .storage()
+        .system()
+        .account_iter(None).await?;
+
     while let Some((key, account)) = iter.next().await? {
-        println!("{:?}: {}", key, account.data.free);
+        println!("{}: {}", hex::encode(key), account.data.free);
     }
     Ok(())
 }

src/lib.rs

@@ -100,6 +100,7 @@ pub use crate::{
         SystemProperties,
     },
     storage::{
+        KeyIter,
         StorageEntry,
         StorageEntryKey,
         StorageMapKey,