Add state_queryStorageAt RPC (#2082)

* Add state_queryStorageAt RPC

* Add queryStorageAt rpc

* Clanup merge

packages/api/src/augment/rpc.ts

@@ -201,6 +201,10 @@ declare module '@polkadot/rpc-core/types.jsonrpc' {
        * Query historical storage entries (by key) starting from a start block
        **/
       queryStorage: AugmentedRpc<<T = Codec[]>(keys: Vec<StorageKey> | (StorageKey | string | Uint8Array | any)[], fromBlock?: Hash | Uint8Array | string, toBlock?: Hash | Uint8Array | string) => Observable<[Hash, T][]>>;
+      /**
+       * Query storage entries (by key) starting at block hash given as the second parameter
+       **/
+      queryStorageAt: AugmentedRpc<<T = Codec[]>(keys: Vec<StorageKey> | (StorageKey | string | Uint8Array | any)[], at?: Hash | Uint8Array | string) => Observable<T>>;
       /**
        * Retrieves the runtime version via subscription
        **/

packages/rpc-core/src/index.ts

@@ -188,7 +188,7 @@ export default class Rpc implements RpcInterface {
         map(([params, result]): any =>
           isRaw
             ? this.registry.createType('Raw', result)
-            : this.formatOutput(def, params, result)
+            : this.formatOutput(method, def, params, result)
         ),
         catchError((error): any => {
           logErrorMessage(method, def, error);
@@ -247,7 +247,7 @@ export default class Rpc implements RpcInterface {
               observer.next(
                 isRaw
                   ? this.registry.createType('Raw', result)
-                  : this.formatOutput(def, params, result)
+                  : this.formatOutput(method, def, params, result)
               );
             } catch (error) {
               observer.error(error);
@@ -317,7 +317,7 @@ export default class Rpc implements RpcInterface {
     return ['0x3a636f6465'].includes(key.toHex());
   }
 
-  private formatOutput (rpc: DefinitionRpc, params: Codec[], result?: any): Codec | Codec[] {
+  private formatOutput (method: string, rpc: DefinitionRpc, params: Codec[], result?: any): Codec | Codec[] {
     if (rpc.type === 'StorageData') {
       const key = params[0] as StorageKey;
 
@@ -331,10 +331,15 @@ export default class Rpc implements RpcInterface {
     } else if (rpc.type === 'StorageChangeSet') {
       return this.formatStorageSet(params[0] as Vec<StorageKey>, result.changes);
     } else if (rpc.type === 'Vec<StorageChangeSet>') {
-      return result.map(({ block, changes }: { block: string; changes: [string, string | null][] }): [Hash, Codec[]] => [
+      const mapped = result.map(({ block, changes }: { block: string; changes: [string, string | null][] }): [Hash, Codec[]] => [
         this.registry.createType('Hash', block),
         this.formatStorageSet(params[0] as Vec<StorageKey>, changes)
       ]);
+
+      // we only query at a specific block, not a range - flatten
+      return method === 'queryStorageAt'
+        ? mapped[0][1]
+        : mapped;
     }
 
     return createTypeUnsafe(this.registry, rpc.type, [result]);

packages/typegen/src/generate/rpc.ts

@@ -34,6 +34,8 @@ export default function generateRpcTypes (dest = 'packages/api/src/augment/rpc.t
             return createDocComments(6, [def.description]) + indent(6)(`getStorage: AugmentedRpc<<T = Codec>(key: ${StorageKeyTye}, block?: Hash | Uint8Array | string) => Observable<T>>;`);
           } else if (methodName === 'queryStorage') {
             return createDocComments(6, [def.description]) + indent(6)(`queryStorage: AugmentedRpc<<T = Codec[]>(keys: Vec<StorageKey> | (${StorageKeyTye})[], fromBlock?: Hash | Uint8Array | string, toBlock?: Hash | Uint8Array | string) => Observable<[Hash, T][]>>;`);
+          } else if (methodName === 'queryStorageAt') {
+            return createDocComments(6, [def.description]) + indent(6)(`queryStorageAt: AugmentedRpc<<T = Codec[]>(keys: Vec<StorageKey> | (${StorageKeyTye})[], at?: Hash | Uint8Array | string) => Observable<T>>;`);
           } else if (methodName === 'subscribeStorage') {
             return createDocComments(6, [def.description]) + indent(6)(`subscribeStorage: AugmentedRpc<<T = Codec[]>(keys: Vec<StorageKey> | (${StorageKeyTye})[]) => Observable<T>>;`);
           }

packages/types/src/interfaces/state/definitions.ts

@@ -268,9 +268,24 @@ export default {
           type: 'Vec<StorageKey>'
         },
         {
-          name: 'startBlock',
+          name: 'fromBlock',
           type: 'Hash'
         },
+        {
+          name: 'toBlock',
+          type: 'BlockHash',
+          isOptional: true
+        }
+      ],
+      type: 'Vec<StorageChangeSet>'
+    },
+    queryStorageAt: {
+      description: 'Query storage entries (by key) starting at block hash given as the second parameter',
+      params: [
+        {
+          name: 'keys',
+          type: 'Vec<StorageKey>'
+        },
         {
           name: 'at',
           type: 'BlockHash',