Api metadata

packages/api/src/Base.ts

@@ -107,7 +107,6 @@ export default abstract class ApiBase<CodecResult, SubscriptionResult> implement
     const thisProvider = options.source
       ? options.source._rpcBase._provider.clone()
       : options.provider;
-
     this._options = options;
     this._type = type;
     this._eventemitter = new EventEmitter();
@@ -361,7 +360,6 @@ export default abstract class ApiBase<CodecResult, SubscriptionResult> implement
 
           this.emit('ready', this);
         }
-
         healthTimer = setInterval(() => {
           this._rpcRx.system.health().toPromise().catch(() => {
             // ignore
@@ -374,14 +372,26 @@ export default abstract class ApiBase<CodecResult, SubscriptionResult> implement
   }
 
   private async loadMeta (): Promise<boolean> {
+    const {prebundles = {}} = this._options;
     // only load from on-chain if we are not a clone (default path), alternatively
     // just use the values from the source instance provided
     if (!this._options.source || !this._options.source._isReady) {
-      this._runtimeMetadata = await this._rpcBase.state.getMetadata();
-      this._runtimeVersion = await this._rpcBase.chain.getRuntimeVersion();
-      this._genesisHash = await this._rpcBase.chain.getBlockHash(0);
-
-      // get unique types & validate
+      [this._genesisHash, this._runtimeVersion] = await Promise.all([
+        this._rpcBase.chain.getBlockHash(0),
+        this._rpcBase.chain.getRuntimeVersion()
+      ]);
+      if (`${this._genesisHash}${(this._runtimeVersion as RuntimeVersion).specVersion}` in prebundles) {
+        try {
+          const rpcData = prebundles[`${this._genesisHash}${(this._runtimeVersion as RuntimeVersion).specVersion}`];
+          const metadata = new Metadata(rpcData);
+          this._runtimeMetadata = metadata;
+          this.runtimeMetadata.getUniqTypes(false);
+        } catch (e) {
+          this._runtimeMetadata = await this._rpcBase.state.getMetadata();
+        }
+      } else {
+        this._runtimeMetadata = await this._rpcBase.state.getMetadata();
+      }
       this.runtimeMetadata.getUniqTypes(false);
     } else {
       this._runtimeMetadata = this._options.source.runtimeMetadata;

packages/api/src/types.ts

@@ -132,6 +132,10 @@ export interface ApiOptions {
    * uses types not available in the base Substrate runtime.
    */
   types?: RegistryTypes;
+
+  prebundles?: {
+    [key: string]: string
+  };
 }
 
 export interface ApiInterface$Decorated<CodecResult, SubscriptionResult> {