Metadata V16: Implement support for Pallet View Functions (#1981)

* Support Pallet View Functions in Subxt * fmt * clippy * Move a little view function logic to subxt_core * clippy * Add back check that prob isnt needed * avoid vec macro in core * Add view funciton test and apply various fixes to get it working * Add test for dynamic view fn call and fix issues * clippy * fix test-runtime * fmt * remove export * avoid vec for nostd core * use const instead of fn for view fn call name * Update to support latest unstable metadata * Update metadata stripping tests for new v16 version
2026-06-14 01:41:09 +00:00 · 2025-04-24 14:42:07 +01:00
parent 21b3f52191
commit 4524590821
28 changed files with 875 additions and 108 deletions
@@ -0,0 +1,69 @@
+// Copyright 2019-2024 Parity Technologies (UK) Ltd.
+// This file is dual-licensed as Apache-2.0 or GPL-3.0.
+// see LICENSE for license details.
+
+//! Encode View Function payloads, decode the associated values returned from them, and validate
+//! static View Function payloads.
+
+pub mod payload;
+
+use crate::error::{Error, MetadataError};
+use crate::metadata::{DecodeWithMetadata, Metadata};
+use alloc::vec::Vec;
+use payload::Payload;
+
+/// Run the validation logic against some View Function payload you'd like to use. Returns `Ok(())`
+/// if the payload is valid (or if it's not possible to check since the payload has no validation hash).
+/// Return an error if the payload was not valid or something went wrong trying to validate it (ie
+/// the View Function in question do not exist at all)
+pub fn validate<P: Payload>(payload: &P, metadata: &Metadata) -> Result<(), Error> {
+    let Some(static_hash) = payload.validation_hash() else {
+        return Ok(());
+    };
+
+    let view_function = metadata
+        .view_function_by_query_id(payload.query_id())
+        .ok_or_else(|| MetadataError::ViewFunctionNotFound(*payload.query_id()))?;
+    if static_hash != view_function.hash() {
+        return Err(MetadataError::IncompatibleCodegen.into());
+    }
+
+    Ok(())
+}
+
+/// The name of the Runtime API call which can execute
+pub const CALL_NAME: &str = "RuntimeViewFunction_execute_view_function";
+
+/// Encode the bytes that will be passed to the "execute_view_function" Runtime API call,
+/// to execute the View Function represented by the given payload.
+pub fn call_args<P: Payload>(payload: &P, metadata: &Metadata) -> Result<Vec<u8>, Error> {
+    let mut call_args = Vec::with_capacity(32);
+    call_args.extend_from_slice(payload.query_id());
+
+    let mut call_arg_params = Vec::new();
+    payload.encode_args_to(metadata, &mut call_arg_params)?;
+
+    use codec::Encode;
+    call_arg_params.encode_to(&mut call_args);
+
+    Ok(call_args)
+}
+
+/// Decode the value bytes at the location given by the provided View Function payload.
+pub fn decode_value<P: Payload>(
+    bytes: &mut &[u8],
+    payload: &P,
+    metadata: &Metadata,
+) -> Result<P::ReturnType, Error> {
+    let view_function = metadata
+        .view_function_by_query_id(payload.query_id())
+        .ok_or_else(|| MetadataError::ViewFunctionNotFound(*payload.query_id()))?;
+
+    let val = <P::ReturnType as DecodeWithMetadata>::decode_with_metadata(
+        &mut &bytes[..],
+        view_function.output_ty(),
+        metadata,
+    )?;
+
+    Ok(val)
+}