Rework Subxt API to support offline and dynamic transactions (#593)

* WIP API changes

* debug impls

* Get main crate compiling with first round of changes

* Some tidy up

* Add WithExtrinsicParams, and have SubstrateConfig + PolkadotConfig, not DefaultConfig

* move transaction into extrinsic folder

* Add runtime updates back to OnlineClient

* rework to be 'client first' to fit better with storage + events

* add support for events to Client

* tidy dupe trait bound

* Wire storage into client, but need to remove static reliance

* various tidy up and start stripping codegen to remove bits we dont need now

* First pass updating calls and constants codegen

* WIP storage client updates

* First pass migrated runtime storage over to new format

* pass over codegen to generate StorageAddresses and throw other stuff out

* don't need a Call trait any more

* shuffle things around a bit

* Various proc_macro fixes to get 'cargo check' working

* organise what's exposed from subxt

* Get first example working; balance_transfer_with_params

* get balance_transfer example compiling

* get concurrent_storage_requests.rs example compiling

* get fetch_all_accounts example compiling

* get a bunch more of the examples compiling

* almost get final example working; type mismatch to look into

* wee tweaks

* move StorageAddress to separate file

* pass Defaultable/Iterable info to StorageAddress in codegen

* fix storage validation ne, and partial run through example code

* Remove static iteration and strip a generic param from everything

* fix doc tests in subxt crate

* update test utils and start fixing frame tests

* fix frame staking tests

* fix the rest of the test compile issues, Borrow on storage values

* cargo fmt

* remove extra logging during tests

* Appease clippy and no more need for into_iter on events

* cargo fmt

* fix dryRun tests by waiting for blocks

* wait for blocks instead of sleeping or other test hacks

* cargo fmt

* Fix doc links

* Traitify StorageAddress

* remove out-of-date doc comments

* optimise decoding storage a little

* cleanup tx stuff, trait for TxPayload, remove Err type param and decode at runtime

* clippy fixes

* fix doc links

* fix doc example

* constant address trait for consistency

* fix a typo and remove EncodeWithMetadata stuff

* Put EventDetails behind a proper interface and allow decoding into top level event, too

* fix docs

* tweak StorageAddress docs

* re-export StorageAddress at root for consistency

* fix clippy things

* Add support for dynamic values

* fix double encoding of storage map key after refactor

* clippy fix

* Fixes and add a dynamic usage example (needs new scale_value release)

* bump scale_value version

* cargo fmt

* Tweak event bits

* cargo fmt

* Add a test and bump scale-value to 0.4.0 to support this

* remove unnecessary vec from dynamic example

* Various typo/grammar fixes

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

* Address PR nits

* Undo accidental rename in changelog

* Small PR nits/tidyups

* fix tests; codegen change against latest substrate

* tweak storage address util names

* move error decoding to DecodeError and expose

* impl some basic traits on the extrinsic param builder

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

examples/examples/fetch_constants.rs

@@ -2,18 +2,17 @@
 // This file is dual-licensed as Apache-2.0 or GPL-3.0.
 // see LICENSE for license details.
 
-//! To run this example, a local polkadot node should be running. Example verified against polkadot 0.9.18-4542a603cc-aarch64-macos.
+//! To run this example, a local polkadot node should be running. Example verified against polkadot polkadot 0.9.25-5174e9ae75b.
 //!
 //! E.g.
 //! ```bash
-//! curl "https://github.com/paritytech/polkadot/releases/download/v0.9.18/polkadot" --output /usr/local/bin/polkadot --location
+//! curl "https://github.com/paritytech/polkadot/releases/download/v0.9.25/polkadot" --output /usr/local/bin/polkadot --location
 //! polkadot --dev --tmp
 //! ```
 
 use subxt::{
-    ClientBuilder,
-    DefaultConfig,
-    PolkadotExtrinsicParams,
+    OnlineClient,
+    PolkadotConfig,
 };
 
 // Generate the API from a static metadata path.
@@ -24,22 +23,14 @@ pub mod polkadot {}
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     tracing_subscriber::fmt::init();
 
-    // Upon connecting to the target polkadot node, the node's metadata is downloaded (referred to
-    // as the runtime metadata).
-    let api = ClientBuilder::new()
-        .build()
-        .await?
-        .to_runtime_api::<polkadot::RuntimeApi<DefaultConfig, PolkadotExtrinsicParams<DefaultConfig>>>();
+    // Create a client to use:
+    let api = OnlineClient::<PolkadotConfig>::new().await?;
 
-    // Constants are queried from the node's runtime metadata.
-    // Query the `ExistentialDeposit` constant from the `Balances` pallet.
-    let existential_deposit = api
-        // This is the constants query.
-        .constants()
-        // Constant from the `Balances` pallet.
-        .balances()
-        // Constant name.
-        .existential_deposit()?;
+    // Build a constant address to query:
+    let address = polkadot::constants().balances().existential_deposit();
+
+    // Look it up:
+    let existential_deposit = api.constants().at(&address)?;
 
     println!("Existential Deposit: {}", existential_deposit);