@leovigna/web3-redux

Web3 Redux

Web3 Redux Library.

Roadmap

To Do

• Default NetworkId
  • ✅ Block (missing for reducer actions)
  • ✅ Contract (missing for reducer actions)
  • EthCall
  • Transaction
• Gas Price Fetch
• ✅ ContractEvent: Test filtering
• Accounts: balance, nonce
• Track latestBlock number in store
• ✅ ContractEvent: Separate entity in store to avoid Contract mutations
• Network add without id, fetch chainId with request
• Loading component/helper for initialization
• Error handling and test error handling
• Smoother Metamask Integration, Add Network RPC request
• Contract.send() rpc optimization (currently each send incurs a heavy penalty for 21 blocks making duplicate/unecessary getBlockByNumber and fetchReceipt calls). See https://web3js.readthedocs.io/en/v1.3.4/web3-eth.html?highlight=21%20blocks#transactionconfirmationblocks
• Mempool monitoring
• ImmutableJS

Completed

• ✅ @reduxjs/toolkit Actions
• ✅ ContractCall: Use regular web3 contract call as opposed to encoding/decoding (allows more flexibility)
• ✅ Usage with Metamask example: Use metamask as wallet provider + custom rpc
• ✅ Batched Multicall.js https://github.com/makerdao/multicall

Table of Contents

• Installing
• Getting Started
  • Initialize the Redux Store
  • Initialize Networks
    • Automatic
    • Manual
• Displaying React Components
• Syncing
  • Block Header Sync
  • Event Sync
  • Contract Call Sync
• Selectors
• Redux State
• Advanced
  • Optimizing Contract Call Sync
  • Custom Contract Call Sync
• Additional Documentation
• Built with
• License

Installing

npm install @leovigna/web3-redux

Getting Started

Initialize the Redux Store

web3-redux can be added to your existing Redux store. The web3Reducer MUST be stored at the web3Redux key in your store.

import { combineReducers, createStore, applyMiddleware } from 'redux';
import createSagaMiddleware from 'redux-saga';
import { web3Reducer, web3Saga } from '@leovigna/web3-redux';

const reducers = combineReducers({
    web3Redux: web3Reducer,
});

const sagaMiddleware = createSagaMiddleware();
const store = createStore(reducers, applyMiddleware(sagaMiddleware));
sagaMiddleware.run(web3Saga);

export default store;

Initialize Networks

To start web3-redux, you can either use the helper WEB3_REDUX/INITIALIZE action or manually add networks and block subscriptions. While a block subscription is optional, it is in most cases necessary to enable syncing the latest on-chain data for your smart contracts.

Usage with metamask

See Manual Network Initialization for more detail. Metamask can cause issues as the injected Web3 instance is mutable and changes as users change networks. To mitigate this, Networks can be initialized with 2 web3 instances, one for read-only calls (eg. Infura) and one for wallet signed send transactions (Metamask). This way, subcriptions and call syncs can continue to work even if a user changes networks.

Override the optional web3Sender parameter when initializing the Network and set it to the injected Web3 instance. The regular read-only web3 instance should

const web3Sender = window.web3; //Metamask wallet, used for send transactions
const web3ReadOnly = new Web3('ws://localhost:8545'); //Used for calls/subscriptions
store.dispatch(Network.create({ networkId: '1', web3: web3ReadOnly, web3Sender }));

Automatic

You can dispatch a WEB3_REDUX/INITIALIZE action to initialize multiple networks.

store.dispatch(Web3Redux.initialize());

A set of default ethereum networks will be initialized if an environment variable with the rpc endpoint value is set. We strongly recommend using a websocket rpc as otherwise subscriptions will not be possible. The following default networks are supported:

• Local: LOCAL_RPC (eg. ws://localhost:8545)
• Mainnet: MAINNET_RPC (eg. wss://mainnet.infura.io/ws/v3/<API_KEY>)
• Ropsten: ROPSTEN_RPC
• Kovan: KOVAN_RPC
• Rinkeby: RINKEBY_RPC
• Goerli: GOERLI_RPC

The environment variables are also supported with the prefixes REACT_APP_* and NEXT_PUBLIC_*.

Alternatively, you can pass your own set of networks with web3 instances to the initialize action:

store.dispatch(Web3Redux.initialize({ networks: [{ networkId: '1', web3 }] }));

Block Sync By default, the initialize action will also start a block sync for each network. You can disable this with:

store.dispatch(Web3Redux.initialize({ blockSubscribe: false }));

Or customize it with:

store.dispatch(Web3Redux.initialize({ blockSubscribe: [{ networkId: '1' }] }));

Manual

Add a network All entities in the web3-redux stored are indexed by networkId. web3-redux let's you sync multiple networks concurrently (eg. sync Mainnet & Ropsten blocks). To enable this however, you must first configure a network by adding it to the store and passing it a web3 instance.

store.dispatch(Network.create({ networkId: '1', web3 }));

Start a block subscription To sync with on-chain events, it's a good idea to start a block subscription as it can be used as a reference point to keep data fresh. This is recommended but not required as some apps might use a different refresh mechanism.

store.dispatch(Block.subscribe({ networkId: '1' }));

Add a contract

One you've add a network and started the block sync, add a contract and make a call.

store.dispatch(Contract.create({ networkId: '1', address: '0x000...', abi: ERC20ABI }));
store.dispatch(Contract.call({
    networkId: '1',
    address: '0x000...',
    method: 'balanceOf',
    args: ['0x111...'],
}));

const balance = Contract.selectContractCall(state, '1-0x000...', 'balanceOf', { args: ['0x0111...', from: web3.eth.defaultAccount ]})

//Alternatively, fetch things manually
const contract = Contract.selectSingle(state, '1-0x000...')
const balanceOf = contract.methods.balanceOf
const argsHash = Contract.callArgsHash({ args: ['0x111...'] }) //([0x111...]).call(latest,web3.eth.defaultAccount)
const value = balanceOf['([0x111...]).call(latest,0x222...)'].value

Displaying React Components

To display web3-redux data in your React components, you can either parse the raw state or use web3-redux's state selectors (recommended). See Selectors section for a description of all web3-redux selectors.

Below a short example component using the BlockSelector to display all blocks.

import React from 'react';
import { useSelector } from 'react-redux';
import { Block } from '@leovigna/web3-redux';

export default function Blocks() {
    const blocks: Block.Block[] = useSelector(BlockSelector.selectMany);
    return (
        <div>
            <h1>Blocks</h1>
            <div>{JSON.stringify(blocks)}</div>
        </div>
    );
}

For a more complete example React app checkout web3-redux-react-example.

Syncing

web3-redux comes with a built-in sync features.

Block Header Sync

This uses web3.eth.subscribe("newBlockHeaders"). Your web3 provider MUST support websocket subscriptions.

Dispatch a Block/SUBSCRIBE action to start a block sync. Only one active block sync per networkId is allowed, and duplicate actions will be ignored. Unsubscribe with a Block/UNSUBSCRIBE action.

//Subscribe blocks
store.dispatch(Block.subscribe({ networkId }));
//Unsubscribe blocks
store.dispatch(Block.unsubscribe({ networkId }));

Event Sync

This uses web3.eth.Contract.events.MyEvent(). Your web3 provider MUST support websocket subscriptions.

Before intiating an event sync you must first create a contract with a Contract/CREATE action:

store.dispatch(Contract.create({ networkId, address, abi});

Dispatch a Contract/EVENT_SUBSCRIBE action to start an event sync. Event syncs are unique by contract address and event name. Duplicate actions will be ignored. Unsubscribe with a Contract/EVENT_UNSUBSCRIBE action.

store.dispatch(Contract.eventSubscribe({ networkId, address, eventName }));

Contract Call Sync

web3-redux offers enhanced customizability of contract call syncing to avoid unecessary rpc calls. Contract call syncing is achieved by refreshing contract calls based on a set of parameters. To initiate contract call syncing, one must first dispatch a ContractCallAction.

There are 3 types of contract call syncing:

• No sync: Call contract method once
• Block sync (Contract/CALL_BLOCK_SYNC): Call contract and refresh every block.
• Transaction sync (Contract/CALL_TRANSACTION_SYNC): Call contract and refresh every time a block includes a transaction to the contract.

Note: Both block sync and transaction sync require an existing block subscription to be first created.

By default we use Transaction syncing. See Advanced/Optimising Contract Call Sync for more info.

Selectors

web3-redux exports a set of reselect selectors to let you easily read data from the store.

import { Block, Transaction, Contract } from '@leovigna/web3-redux';
import store from './store.ts';

const state = store.getState();

//Default Redux-ORM selectors
//Select full collections
const blocks: Block.BlockHeader[] = Block.selectMany(state);
const transactions: Transaction.Transaction[] = Transaction.selectMany(state);
const contracts: Contract.Contract[] = Contract.selectMany(state);

//Select single instance by id
const networkId = 1;
const block42: Block.BlockHeader = Block.selectSingle(state, [`${networkId}-42`]); //block 42 on networkId 1

//Select multiple instances by id
const networkId = 1;
const [block43, block44]: [Block.BlockHeader, Block.BlockHeader] = Block.selectMany(state, [
    `${networkId}-43`,
    `${networkId}-44`,
]);

//Custom selectors
//Select blocks with transactions (also works with id/[id] filtering)
const blocksWithTransactions: Block.BlockTransactionObject[] = Block.selectManyBlockTransaction(state);

Redux State

export interface Web3ReduxStore {
    Network: {
        itemsById: {
            [id: string]: Network; //`${networkId}`
        };
    };
    Block: {
        itemsById: {
            [id: string]: BlockHeader; //`${networkId}-${number}`
        };
    };
    Transaction: {
        itemsById: {
            [id: string]: Transaction; //`${networkId}-${hash}`
        };
    };
    Contract: {
        itemsById: {
            [id: string]: Contract; //`${networkId}-${address}`
        };
    };
    EthCall: {
        itemsById: {
            [id: string]: EthCall; //`${networkId}-${from}-${to}-${data}-${gas}-${gasPrice}`.
        };
    };
}

Advanced

Optimizing Contract Call Sync

By default, contracts use Transaction syncing but this can be customized for each specific contract call. This is can be a sub-optimal or even incorrect sync strategy.

Transaction syncing can be sub-optimal if a call's return value never changes. For example, an ERC20 token's name or symbol. In this case simply disable syncing with sync: false.

Transaction syncing assumes that the contract call values are only dependent on your contract's state and that this state is only changed by direct transactions to your contract. The basic logic for Transaction syncing is as follows: For each transaction in a new block, update contract call if tx.to == contract.address. Examples of cases where this assumption might be incorrect include:

• Contract call return value depends on block number
• Contract state can be changed by a call to some proxy contract

In these cases we recommend switching to Block syncing, which will poll the contract call at every block. For even better optimization, it might be interesting in some cases to use a custom block or transaction sync.

Custom Contract Call Sync

The interface of ContractCallBlockSync and ContractCallTransactionSync use a filter function returning whether a contract call should update. Customizing the filter function can help you create more optimized syncing depending on your use case.

export interface ContractCallBlockSync {
    type: typeof CALL_BLOCK_SYNC;
    filter: (block: BlockHeader) => boolean;
}

export interface ContractCallTransactionSync {
    type: typeof CALL_TRANSACTION_SYNC;
    filter: (transaction: Transaction) => boolean;
}

Example sync strategies:

• Sync every 5 blocks: (block) => block.number % 5 == 0
• Sync for transactions to contract or proxy: (tx) => tx.to === contract.address || tx.to === proxy.address

Additional Documentation

Additional documentation is available at leovigna.github.io/web3-redux

Built with

• reselect
• redux-orm
• web3.js

License

2021 Leo Vigna MIT License.