state_getMetadata - Bittensor RPC Method
Get runtime metadata on Bittensor. Essential for decoding storage, building extrinsics, and discovering available pallets and calls on the decentralized machine intelligence network built around subnets, TAO staking, and validator-miner coordination.
Returns the runtime metadata for Bittensor as a SCALE-encoded hex string. Metadata describes all available pallets, storage items, calls, events, errors, and type definitions — everything needed to interact with the chain programmatically.
Why Bittensor? Build on the decentralized machine intelligence network built around subnets, TAO staking, and validator-miner coordination with Yuma Consensus, subnet-based specialization, dual Substrate and EVM surfaces, and onchain incentive coordination.
When to Use This Method
state_getMetadata is essential for AI/ML developers, subnet operators, and teams building decentralized machine learning applications:
- Runtime Introspection — Discover available pallets, calls, and storage items on Bittensor
- Extrinsic Building — Get call signatures and type information for constructing transactions for decentralized AI inference, subnet-specific AI models, TAO staking, and cross-subnet AI collaboration
- Storage Key Generation — Build correct storage keys from metadata type definitions
- Client Generation — Auto-generate typed APIs and SDKs from the runtime metadata
- Upgrade Awareness — Detect metadata changes after runtime upgrades
Code Examples
Common Use Cases
1. Discover Available Pallets and Calls
Explore what functionality is available on Bittensor:
async function explorePallets(api) {
const metadata = await api.rpc.state.getMetadata();
const pallets = metadata.asLatest.pallets;
for (const pallet of pallets) {
const name = pallet.name.toString();
const hasCalls = pallet.calls.isSome;
const hasStorage = pallet.storage.isSome;
const hasEvents = pallet.events.isSome;
console.log(`${name}: calls=${hasCalls} storage=${hasStorage} events=${hasEvents}`);
}
}2. Build Storage Keys from Metadata
Generate correct storage keys for querying chain state:
import { xxhashAsHex } from '@polkadot/util-crypto';
function buildStorageKey(palletName, storageName) {
const palletHash = xxhashAsHex(palletName, 128);
const storageHash = xxhashAsHex(storageName, 128);
return palletHash + storageHash.slice(2); // Concatenate without duplicate 0x
}
// Example: Build key for System.Account storage
const key = buildStorageKey('System', 'Account');
console.log('Storage prefix key:', key);3. Metadata Version Tracking
Track metadata changes across runtime upgrades on Bittensor:
async function compareMetadataVersions(api, blockA, blockB) {
const hashA = await api.rpc.chain.getBlockHash(blockA);
const hashB = await api.rpc.chain.getBlockHash(blockB);
const metaA = await api.rpc.state.getMetadata(hashA);
const metaB = await api.rpc.state.getMetadata(hashB);
const palletsA = new Set(metaA.asLatest.pallets.map(p => p.name.toString()));
const palletsB = new Set(metaB.asLatest.pallets.map(p => p.name.toString()));
const added = [...palletsB].filter(p => !palletsA.has(p));
const removed = [...palletsA].filter(p => !palletsB.has(p));
console.log('Added pallets:', added);
console.log('Removed pallets:', removed);
}Error Handling
| Error Code | Description | Solution |
|---|---|---|
| -32603 | Internal error | Node may be syncing — retry with backoff |
| -32602 | Invalid params | Verify block hash is valid hex with 0x prefix |
| -32601 | Method not found | Verify the node supports this RPC method |
| -32005 | Rate limit exceeded | Cache metadata locally — it only changes on runtime upgrades |
Related Methods
state_getRuntimeVersion— Get runtime version (check before re-fetching metadata)state_getStorage— Query storage using keys derived from metadatastate_call— Call runtime APIs described in metadata
state_getStorage
Read a storage value by key on Bittensor. Query account balances, pallet state, and any on-chain data using SCALE-encoded storage keys for decentralized AI inference, subnet-specific AI models, TAO staking, and cross-subnet AI collaboration.
state_getRuntimeVersion
Get the runtime version on Bittensor. Essential for compatibility checking, upgrade detection, and transaction construction on the decentralized machine intelligence network built around subnets, TAO staking, and validator-miner coordination.