v0.50.0: Integrate frame-decode, redo storage APIs and break up Error. (#2100)

* WIP integrating new frame-decode and working out new storage APIS

* WIP: first pass adding new storage things to subxt-core

* Second pass over Address type and start impl in Subxt

* WIP new storage APIs

* WIP New storage APIs roughly completed, lots of errors still

* Remove PlainorMap enum; plain and map values now use same struct to simplify usage

* Begin 'fixing' errors

* WIP splitting errors and tidying payload/address traits

* Get subxt-core compiling

* Small fixes in subxt-core and remove metadata mod

* subxt-core: cargo check --all-targets passes

* Fix test

* WIP starting to update subxt from subxt-core changes

* WIP splitting up subxt errors into smaller variants

* WIP errors: add DispatchError errors

* Port new Storage APIs to subxt-core

* cargo check -p subxt passes

* Quick-fix errors in subxt-cli (explore subcommand)

* fmt

* Finish fixing codegen up and start fixing examples

* get Subxt examples compiling and bytes_at for constants

* Add some arcs to limit lifetimes in subxt/subxt-core storage APIs

* A little Arcing to allow more method chaining in Storage APIs, aligning with Subxt

* Update codegen test

* cargo check --all-targets passing

* cargo check --features 'unstable-light-client' passing

* clippy

* Remove unused dep in subxt

* use published frame-decode

* fix wasm-example

* Add new tx extension to fix daily tests

* Remove unused subxt_core::dynamic::DecodedValue type

* Update book to match changes

* Update docs to fix more broken bits

* Add missing docs

* fmt

* allow larger result errs for now

* Add missing alloc imports in subxt-core

* Fix doc tests and fix bug getting constant info

* Fix V14 -> Metadata transform for storage & constants

* Fix parachain example

* Fix FFI example

* BlockLength decodes t ostruct, not u128

* use fetch/iter shorthands rather than entry in most storage tests

* Fix some integration tests

* Fix Runtime codegen tests

* Expose the dynamic custom_value selecter and use in a UI test

* Update codegen metadata

* Tidy CLI storage query and support (str,str) as a storage address

* Add (str,str) as valid constant address too

* Show string tuple in constants example

* Via the magic of traits, avoid needing any clones of queries/addresses and accept references to them

* clippy

subxt/examples/storage_iterating_dynamic.rs

@@ -1,23 +1,41 @@
 #![allow(missing_docs)]
-use subxt::{OnlineClient, PolkadotConfig, dynamic::Value};
+use subxt::ext::futures::StreamExt;
+use subxt::utils::AccountId32;
+use subxt::{
+    OnlineClient, PolkadotConfig,
+    dynamic::{At, Value},
+};
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     // Create a new API client, configured to talk to Polkadot nodes.
     let api = OnlineClient::<PolkadotConfig>::new().await?;
 
-    // Build a dynamic storage query to iterate account information.
-    // With a dynamic query, we can just provide an empty vector as the keys to iterate over all entries.
-    let keys: Vec<Value> = vec![];
-    let storage_query = subxt::dynamic::storage("System", "Account", keys);
+    // Build a dynamic storage query to access account information.
+    // here, we assume that there is one value to provide at this entry
+    // to access a value; an AccountId32. In this example we don't know the
+    // return type and so we set it to `Value`, which anything can decode into.
+    let storage_query = subxt::dynamic::storage::<(AccountId32,), Value>("System", "Account");
 
-    // Use that query to return an iterator over the results.
-    let mut results = api.storage().at_latest().await?.iter(storage_query).await?;
+    // Use that query to access a storage entry, iterate over it and decode values.
+    let client_at = api.storage().at_latest().await?;
+    let mut values = client_at.entry(storage_query)?.iter(()).await?;
 
-    while let Some(Ok(kv)) = results.next().await {
-        println!("Keys decoded: {:?}", kv.keys);
-        println!("Key: 0x{}", hex::encode(&kv.key_bytes));
-        println!("Value: {:?}", kv.value.to_value()?);
+    while let Some(kv) = values.next().await {
+        let kv = kv?;
+
+        // The key decodes into the first type we provided in the address. Since there's just
+        // one key, it is a tuple of one entry, an AccountId32. If we didn't know how many
+        // keys or their type, we could set the key to `Vec<Value>` instead.
+        let (account_id32,) = kv.key()?.decode()?;
+
+        // The value decodes into the second type we provided in the address. In this example,
+        // we just decode it into our `Value` type and then look at the "data" field in this
+        // (which implicitly assumes we get a struct shaped thing back with such a field).
+        let value = kv.value().decode()?;
+
+        let value_data = value.at("data").unwrap();
+        println!("{account_id32}:\n  {value_data}");
     }
 
     Ok(())