ERC1155

Source: examples/erc1155/

Indexes ERC1155 multi-token events: TransferSingle, TransferBatch, and URI. Demonstrates batch event processing and iterating over arrays in event parameters.

Schema

type Token @entity {
  id: ID!
  uri: String
  totalSupply: BigInt!
}

type Transfer @entity {
  id: ID!
  operator: Bytes!
  from: Bytes!
  to: Bytes!
  tokenId: BigInt!
  value: BigInt!
  blockNumber: BigInt!
  transactionHash: Bytes!
}

Handlers

TransferSingle: Single token transfer — straightforward.

#![allow(unused)]
fn main() {
#[handler]
pub fn handle_transfer_single(event: &ERC1155TransferSingleEvent, ctx: &graphite::EventContext) {
    let id = format!("{}-{}", hex(&ctx.tx_hash), hex(&ctx.log_index));
    Transfer::new(&id)
        .set_operator(event.operator.to_vec())
        .set_from(event.from.to_vec())
        .set_to(event.to.to_vec())
        .set_token_id(event.id.clone())
        .set_value(event.value.clone())
        .set_block_number(ctx.block_number.clone())
        .set_transaction_hash(ctx.tx_hash.to_vec())
        .save();
}
}

TransferBatch: Iterates over the ids and values arrays in the event:

#![allow(unused)]
fn main() {
#[handler]
pub fn handle_transfer_batch(event: &ERC1155TransferBatchEvent, ctx: &graphite::EventContext) {
    for (i, (token_id, value)) in event.ids.iter().zip(event.values.iter()).enumerate() {
        let id = format!("{}-{}-{}", hex(&ctx.tx_hash), hex(&ctx.log_index), i);
        Transfer::new(&id)
            .set_operator(event.operator.to_vec())
            .set_from(event.from.to_vec())
            .set_to(event.to.to_vec())
            .set_token_id(token_id.clone())
            .set_value(value.clone())
            .set_block_number(ctx.block_number.clone())
            .set_transaction_hash(ctx.tx_hash.to_vec())
            .save();
    }
}
}

URI: Updates the token's metadata URI:

#![allow(unused)]
fn main() {
#[handler]
pub fn handle_uri(event: &ERC1155URIEvent, _ctx: &graphite::EventContext) {
    let token_id = hex(&event.id);
    let token = Token::load(&token_id).unwrap_or_else(|| Token::new(&token_id));
    token.set_uri(event.value.clone()).save();
}
}

Key Points

• Array parameters in ERC1155 TransferBatch (ids[], values[]) are decoded as Vec<Vec<u8>> — each inner Vec<u8> is a little-endian BigInt.
• Loop index i in the batch handler is used to disambiguate entity IDs within a single transaction log.
• Token::load(...).unwrap_or_else(|| Token::new(...)) is the idiomatic pattern for upsert when you want to preserve existing fields.

cd examples/erc1155
cargo test