mvx-blockchain-data

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SKILL.md (first lines)

# MultiversX Blockchain Data — `self.blockchain()` API Reference

Complete reference for reading on-chain state in MultiversX smart contracts (SDK v0.64+).

## Caller & Account Info

| Method | Returns | Description |
|--------|---------|-------------|
| `.get_caller()` | `ManagedAddress` | Address that initiated the current call |
| `.get_sc_address()` | `ManagedAddress` | This contract's own address |
| `.get_owner_address()` | `ManagedAddress` | Contract owner address |
| `.check_caller_is_owner()` | `()` | Panics if caller != owner. Equivalent to `#[only_owner]`. |
| `.check_caller_is_user_account()` | `()` | Panics if caller is a smart contract (not an EOA). |
| `.is_smart_contract(address)` | `bool` | Check if an address is a smart contract |
| `.get_shard_of_address(address)` | `u32` | Get shard ID for an address |

```rust
// Owner-only guard (manual alternative to #[only_owner])
self.blockchain().check_caller_is_owner();

// Prevent contract-to-contract calls (anti-flash-loan)
self.blockchain().check_caller_is_user_account();

// Check if target is a SC before sending
let is_sc = self.blockchain().is_smart_contract(&target);
```

## Balances

| Method | Returns | Description |
|--------|---------|-------------|
| `.get_balance(address)` | `BigUint` | EGLD balance of any address |
| `.get_sc_balance(token_id, nonce)` | `BigUint` | This contract's balance of any token (EGLD or ESDT). `token_id` is `impl AsRef<TokenId>`. |
| `.get_esdt_balance(address, token_id, nonce)` | `BigUint` | ESDT balance of any address. `token_id` is `&EsdtTokenIdentifier`. |

```rust
// Check own EGLD balance
let egld = self.blockchain().get_balance(&self.blockchain().get_sc_address());

// Check own ESDT balance (simpler via get_sc_balance)
let balance = self.blockchain().get_sc_balance(&my_token_id, 0u64);
```

## Block Info

### Current Block

| Method | Returns | Description |
|--------|---------|-------------|
| `.get_block_timestamp_seconds()` | `TimestampSeconds` | Block timestamp in seconds (v0.63+) |
| `.get_block_timestamp_millis()` | `TimestampMillis` | Block timestamp in milliseconds (v0.63+) |
| `.get_block_nonce()` | `u64` | Block nonce (height) |
| `.get_block_round()` | `u64` | Block round |
| `.get_block_epoch()` | `u64` | Current epoch |
| `.get_block_round_time_millis()` | `DurationMillis` | Round duration in ms (v0.63+) |
| `.get_block_random_seed()` | `ManagedByteArray<48>` | 48-byte random seed |

### Previous Block

| Method | Returns | Description |
|--------|---------|-------------|
| `.get_prev_block_timestamp_seconds()` | `TimestampSeconds` | Previous block timestamp (seconds) |
| `.get_prev_block_timestamp_millis()` | `TimestampMillis` | Previous block timestamp (ms) |
| `.get_prev_block_nonce()` | `u64` | Previous block nonce |
| `.get_prev_block_round()` | `u64` | Previous block round |
| `.get_prev_block_epoch()` | `u64` | Previous epoch |
| `.get_prev_block_random_seed()` | `ManagedByteArray<48>` | Previous block random seed |

### Epoch Start Info

| Method | Returns | Description |
|--------|---------|-------------|
| `.get_epoch_start_block_timestamp_millis()` | `TimestampMillis` | When current epoch started |
| `.get_epoch_start_block_nonce()` | `u64` | Block nonce at epoch start |
| `.get_epoch_start_block_round()` | `u64` | Block round at epoch start |

### Deprecated Timestamp Methods (Do NOT Use)

| Deprecated | Replacement | Since |
|-----------|-------------|-------|
| `.get_block_timestamp()` | `.get_block_timestamp_seconds()` | v0.63 |
| `.get_block_timestamp_ms()` | `.get_block_timestamp_millis()` | v0.63 |
| `.get_prev_block_timestamp()` | `.get_prev_block_timestamp_seconds()` | v0.63 |
| `.get_prev_block_timestamp_ms()` | `.get_prev_block_timestamp_millis()` | v0.63 |
| `.get_block_round_time_ms()` | `.get_block_round_time_millis()` | v0.63 |
| `.epoch_start_block_timestamp_ms()` | `.get_epoch_start_block_timestamp_millis()` | v0.63 |
| `.epoch_start_block_timestamp_millis()` | `.get_epoch_start_block_timestamp_millis()` | v0.63.1 |
| `.epoch_start_block_nonce()` | `.get_epoch_start_block_nonce()` | v0.63.1 |
| `.epoch_start_block_round()` | `.get_epoch_start_block_round()` | v0.63.1 |

## Transaction Info

| Method | Returns | Description |
|--------|---------|-------------|
| `.get_tx_hash()` | `ManagedByteArray<32>` | Current transaction hash |
| `.get_gas_left()` | `u64` | Remaining gas |
| `.get_state_root_hash()` | `ManagedByteArray<32>` | State root hash |

## ESDT Token Metadata

| Method | Returns | Description |
|--------|---------|-------------|
| `.get_esdt_token_data(address, token_id, nonce)` | `EsdtTokenData` | Full token data (amount, attributes, creator, royalties, URIs, etc.) |
| `.get_esdt_token_type(address, token_id, nonce)` | `EsdtTokenType` | Token type enum (Fungible, NonFungible, SemiFungible, Meta) |
| `.get_token_attributes::<T>(token_id, nonce)` | `T: TopDecode` | Deserialized NFT/SFT attributes from this contract's account |
| `.get_current_esdt_nft_nonce(address, token_id)` | `u64` | Last minted nonce for a token on an address |

```rust
// EsdtTokenData fields:
pub struct EsdtTokenData<M: ManagedTypeApi> {
    pub token_type: EsdtTokenType,
    pub amount: BigUint<M>,
    pub frozen: bool,
    pub hash: ManagedBuffer<M>,
    pub name: ManagedBuffer<M>,
    pub attributes: ManagedBuffer<M>,  // raw bytes — use get_token_attributes for typed
    pub creator: ManagedAddress<M>,
    pub royalties: BigUint<M>,         // 0-10000 (basis points)
    pub uris: ManagedVec<M, ManagedBuffer<M>>,

From multiversx/mx-ai-skills, MIT.

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