Nfts attribute read interface (#13349)

* feat: add custom and system attributes to Inspect

* feat: add nfts runtime api

* fix: pass std feature to runtime api

* fix: api copyright

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>

---------

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>

substrate/frame/nfts/runtime-api/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+name = "pallet-nfts-runtime-api"
+version = "4.0.0-dev"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+license = "Apache-2.0"
+homepage = "https://substrate.io"
+repository = "https://github.com/paritytech/substrate/"
+description = "Runtime API for the FRAME NFTs pallet."
+readme = "README.md"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.2.2", default-features = false, features = ["derive"] }
+frame-support = { version = "4.0.0-dev", default-features = false, path = "../../support" }
+pallet-nfts = { version = "4.0.0-dev", default-features = false, path = "../../nfts" }
+sp-api = { version = "4.0.0-dev", default-features = false, path = "../../../primitives/api" }
+
+[features]
+default = ["std"]
+std = [
+	"codec/std",
+    "frame-support/std",
+	"pallet-nfts/std",
+	"sp-api/std",
+]

substrate/frame/nfts/runtime-api/README.md

@@ -0,0 +1,3 @@
+RPC runtime API for the FRAME NFTs pallet.
+
+License: Apache-2.0

substrate/frame/nfts/runtime-api/src/lib.rs

@@ -0,0 +1,57 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2023 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Runtime API definition for the FRAME NFTs pallet.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use codec::{Decode, Encode};
+use frame_support::dispatch::Vec;
+
+sp_api::decl_runtime_apis! {
+	pub trait NftsApi<AccountId, CollectionId, ItemId>
+	where
+		AccountId: Encode + Decode,
+		CollectionId: Encode,
+		ItemId: Encode,
+	{
+		fn owner(collection: CollectionId, item: ItemId) -> Option<AccountId>;
+
+		fn collection_owner(collection: CollectionId) -> Option<AccountId>;
+
+		fn attribute(
+			collection: CollectionId,
+			item: ItemId,
+			key: Vec<u8>,
+		) -> Option<Vec<u8>>;
+
+		fn custom_attribute(
+			account: AccountId,
+			collection: CollectionId,
+			item: ItemId,
+			key: Vec<u8>,
+		) -> Option<Vec<u8>>;
+
+		fn system_attribute(
+			collection: CollectionId,
+			item: ItemId,
+			key: Vec<u8>,
+		) -> Option<Vec<u8>>;
+
+		fn collection_attribute(collection: CollectionId, key: Vec<u8>) -> Option<Vec<u8>>;
+	}
+}

substrate/frame/nfts/src/impl_nonfungibles.rs

@@ -50,18 +50,48 @@ impl<T: Config<I>, I: 'static> Inspect<<T as SystemConfig>::AccountId> for Palle
 	fn attribute(
 		collection: &Self::CollectionId,
 		item: &Self::ItemId,
-		namespace: &AttributeNamespace<<T as SystemConfig>::AccountId>,
 		key: &[u8],
 	) -> Option<Vec<u8>> {
 		if key.is_empty() {
 			// We make the empty key map to the item metadata value.
 			ItemMetadataOf::<T, I>::get(collection, item).map(|m| m.data.into())
 		} else {
+			let namespace = AttributeNamespace::CollectionOwner;
 			let key = BoundedSlice::<_, _>::try_from(key).ok()?;
 			Attribute::<T, I>::get((collection, Some(item), namespace, key)).map(|a| a.0.into())
 		}
 	}
 
+	/// Returns the custom attribute value of `item` of `collection` corresponding to `key`.
+	///
+	/// By default this is `None`; no attributes are defined.
+	fn custom_attribute(
+		account: &T::AccountId,
+		collection: &Self::CollectionId,
+		item: &Self::ItemId,
+		key: &[u8],
+	) -> Option<Vec<u8>> {
+		let namespace = Account::<T, I>::get((account, collection, item))
+			.map(|_| AttributeNamespace::ItemOwner)
+			.unwrap_or_else(|| AttributeNamespace::Account(account.clone()));
+
+		let key = BoundedSlice::<_, _>::try_from(key).ok()?;
+		Attribute::<T, I>::get((collection, Some(item), namespace, key)).map(|a| a.0.into())
+	}
+
+	/// Returns the system attribute value of `item` of `collection` corresponding to `key`.
+	///
+	/// By default this is `None`; no attributes are defined.
+	fn system_attribute(
+		collection: &Self::CollectionId,
+		item: &Self::ItemId,
+		key: &[u8],
+	) -> Option<Vec<u8>> {
+		let namespace = AttributeNamespace::Pallet;
+		let key = BoundedSlice::<_, _>::try_from(key).ok()?;
+		Attribute::<T, I>::get((collection, Some(item), namespace, key)).map(|a| a.0.into())
+	}
+
 	/// Returns the attribute value of `item` of `collection` corresponding to `key`.
 	///
 	/// When `key` is empty, we return the item metadata value.