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<Tabs queryString="typegen">
<Tab value="evm" label="squid-evm-typegen">
The squid-evm-typegen(1) tool generates TypeScript facades for EVM transactions, logs and eth_call queries. The generated facades are assumed to be used by squids indexing EVM data. The tool takes a JSON ABIs as an input. Those can be specified in three ways:
  1. as a plain JSON file(s): 
    npx squid-evm-typegen src/abi abi/erc20.json
    To include all files in ./abi and add an interface for the Multicall contract, run 
    npx squid-evm-typegen ./src/abi ./abi/*.json --multicall
    You can get JSON ABIs for explorer (Etherscan, Bscscan etc) verified contract by visiting the contract page, going to the “Contract” tab and scrolling down to the “Contract ABI” section. Do not use the “Export ABI” function! Copy the contents to the clipboard and paste them to a new JSON file.
  2. (requires an Etherscan API key) as a contract address. One can pass multiple addresses at once. 
    npx squid-evm-typegen --etherscan-api-key <your_key> src/abi 0xBB9bc244D798123fDe783fCc1C72d3Bb8C189413
Please check if your contract is a proxy when using this method. If it is, consult this page for guidance.
  1. as an arbitrary URL: 
    npx squid-evm-typegen src/abi https://example.com/erc721.json
In all cases typegen will use basename of the ABI as the root name for the generated files. You can change the basename of generated files using the fragment (#) suffix. 
squid-evm-typegen src/abi 0xBB9bc244D798123fDe783fCc1C72d3Bb8C189413#my-contract-name
Arguments:
output-diroutput directory for generated definitions
abiA contract address, an URL or a local path to the ABI file. Accepts multiple contracts.
Options:
--multicallgenerate a facade for the MakerDAO multicall contract. May significantly improve the performance of contract state calls by batching RPC requests
--etherscan-api <url>etherscan API to fetch contract ABI by a known address. By default, https://api.etherscan.io/
--cleandelete output directory before the run
-h, --helpdisplay help for command
The generated modules depend on @subsquid/evm-abi. Please add it to your package.json as a peer dependency if it’s not there already:
npm i @subsquid/evm-abi

​
Usage

The generated utility modules have three intended uses:
  1. Constants: EVM log topic0 values and sighashes for transactions. Example: 
    // generated by evm-typegen
import * as weth from './abi/weth'

const CONTRACT_ADDRESS = '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2'.toLowerCase()

const processor = new EvmBatchProcessor()
  .setPortal('https://portal.sqd.dev/datasets/ethereum-mainnet')
  .addLog({
    address: [CONTRACT_ADDRESS],
    topic0: [
      weth.events.Deposit.topic,
      weth.events.Withdrawal.topic
    ]
  })
  2. Decoding of EVM logs and transactions
  3. Direct chain state queries, including queries to multicall. 
</Tab>
<Tab value="substrate" label="squid-substrate-typegen">
The substrate typegen tool is a part of Squid SDK. It generates TypeScript wrappers for interfacing Substrate events and calls. Usage: 
npx squid-substrate-typegen typegen.json
If necessary, multiple config files can be supplied: 
npx squid-substrate-typegen typegen0.json typegen1.json ...
The structure of the typegen.json config file is best illustrated with an example: 
{
  "outDir": "src/types",
  "specVersions": "https://v2.archive.subsquid.io/metadata/kusama",
  "pallets": {
    // add one such section for each pallet
    "Balances": {
      "events": [
        // list of events to generate wrappers for
        "Transfer"
      ],
      "calls": [
        // list of calls to generate wrappers for
        "transfer_allow_death"
      ],
      "storage": [
        "Account"
      ],
      "constants": [
        "ExistentialDeposit"
      ]
    }
  }
}
The specVersions field is either
  • a metadata service endpoint URL, like
https: “//v2.archive.subsquid.io/metadata/{network}” 
or
- a path to a [`jsonl`](https://jsonlines.org) file generated by [`substrate-metadata-explorer(1)`](https://github.com/subsquid/squid-sdk/tree/master/substrate/substrate-metadata-explorer).


To generate all items defined by a given pallet, set any of the `events`, `calls`, `storage` or `constants` fields to `true`, e.g.

```json
{
"outDir": "src/types",
"specVersions": "kusamaVersions.jsonl",
"pallets": {
 "Balances": {
   // generate wrappers for all Balances pallet constants
   "constants": true
 }
}
}
In the rare cases when the typegen needs a types bundle, supply it alongside metadata:
{
  "outDir": "src/types",
  "specVersions": "westendVersions.jsonl",
  "typesBundle": "westendTypes.json",
  ...
}

​
TypeScript wrappers

Wrappers generated by the typegen command can be found in the specified outDir (src/types by convention). Assuming that this folder is imported as types (e.g. with import * as types from './types'), you’ll be able to find the wrappers at:
  • for events: “types.events.$\{palletName\}.$\{eventName\}”
  • for calls: “types.calls.$\{palletName\}.$\{callName\}”
  • for storage items: “types.storage.$\{palletName\}.$\{storageItemName\}”
  • for constants: “types.constants.$\{palletName\}.$\{constantName\}”
All identifiers (pallet name, call name etc) are lowerCamelCased. E.g. the constant Balances.ExistentialDeposit becomes types.events.balances.existentialDeposit and the call Balances.set_balance becomes types.calls.setBalance.

​
Usage

  1. Item name constants (e.g. events.balances.transfer.name).
  2. Runtime versioning-aware decoding.
  3. Chain storage queries
  4. Runtime constants: 
    import \{constants\} from './types'
// ...
processor.run(new TypeormDatabase(), async ctx => {
  for (let block of ctx.blocks) {
    if (constants.balances.existentialDeposit.v1020.is(block.header)) {
      let c = new constants.balances.existentialDeposit.v1020.get(block.header)
ctx.log.info(Balances.ExistentialDeposit (runtime version V1020): "$\{c\})” } } }) 

```mdx-code-block
</Tab>
<Tab value="ink" label="squid-ink-typegen">
Use squid-ink-typegen to generate facade classes for decoding ink! smart contract data from JSON ABI metadata. Usage: 
npx squid-ink-typegen --abi abi/erc20.json --output src/abi/erc20.ts
The generated source code exposes the decoding methods, some useful types and a class for performing wrapped RPC queries, using @subsquid/ink-abi under the hood 
</Tab>
</Tabs>