NFT Subgraph Workshop at Eth Amsterdam

• Contract to index
• Google Slides for NFT Subgraph Development Workshop
• Questions: twitter.com/schmid_si

Prerequisites

• Install graph-cli: yarn global add @graphprotocol/graph-cli

First Steps

• Find the contract on Etherscan

• Find the contract creation transaction for startBlock

• Download the ABI

• Run this command to initialise the subgraph with events:

graph init \
    --studio \
    --protocol ethereum \
    --from-contract 0xc2c747e0f7004f9e8817db2ca4997657a7746928 \
    --index-events \
    --contract-name Hashmasks \
    --network mainnet \
    hashmasks hashmasks-subgraph

• Inspect the source
• Change startblock:

source:
    address: "0xc2c747e0f7004f9e8817db2ca4997657a7746928"
    abi: Hashmasks
    startBlock: 11743743

– Create new subgraph on Subgraph Studio named "Hashmasks"

• graph auth --studio ...
• yarn deploy

Remove unused Entities and Events

# schema.graphql
type Transfer @entity {
  id: ID!
  from: Bytes! # address
  to: Bytes! # address
  tokenId: BigInt! # uint256
}

Extend events

Make them immutable for performance improvements

type Transfer @entity(immutable: true) {
  id: ID!
  from: Bytes! # address
  to: Bytes! # address
  tokenId: BigInt! # uint256
  timestamp: BigInt!
  blockNumber: BigInt!
}

Use event.transaction.hash.toHex() + "-" + event.logIndex.toString() as the id for events

export function handleTransfer(event: TransferEvent): void {
  let entity = new Transfer(
    event.transaction.hash.toHex() + "-" + event.logIndex.toString()
  )
  entity.blockNumber = event.block.number;
  entity.timestamp = event.block.timestamp;
  entity.from = event.params.from
  entity.to = event.params.to
  entity.tokenId = event.params.tokenId
  entity.save()
}

Store logical entities

• Identify the important entities: Token, Owner, Contract
• Link them

type Transfer @entity(immutable: true) {
  id: ID!
  from: Owner!
  to: Owner!
  token: Token!
  timestamp: BigInt!
  blockNumber: BigInt!
}

type Token @entity {
  id: ID!
  owner: Owner
  uri: String
  transfers: [Transfer!]! @derivedFrom(field: "token")
  contract: Contract
}

type Owner @entity {
  id: Bytes! # Use bytes as ID
  ownedTokens: [Token!]! @derivedFrom(field: "owner")
  balance: BigInt
}

type Contract @entity {
  id: ID!
  name: String
  symbol: String
  totalSupply: BigInt
  mintedTokens: [Token!]! @derivedFrom(field: "contract")
}

Other resources

• https://github.com/Developer-DAO/resources
• https://dev.to/dabit3/the-complete-guide-to-full-stack-ethereum-development-3j13
• https://github.com/itsjerryokolo/CryptoPunks
• https://github.com/dabit3/building-a-subgraph-workshop
• https://thegraph.com/docs/developer/quick-start
• https://thegraph.com/discord