fetch limit order and dec

here, we provide a simple example to fetch limit orders of iZiSwap from an user’s address, and select one of them to decrease(or called cancel)

The full example code of this chapter can be spotted here.

1. fetch limit orders

const chain:BaseChain = initialChainTable[ChainId.BSC]
const rpc = 'https://bsc-dataseed2.defibit.io/'
const web3 = new Web3(new Web3.providers.HttpProvider(rpc))
const account =  web3.eth.accounts.privateKeyToAccount(privateKey)

const limitOrderAddress = '0x9Bf8399c9f5b777cbA2052F83E213ff59e51612B'
const limitOrderManager = getLimitOrderManagerContract(limitOrderAddress, web3)


const testAAddress = '0xCFD8A067e1fa03474e79Be646c5f6b6A27847399'
const testBAddress = '0xAD1F11FBB288Cd13819cCB9397E59FAAB4Cdc16F'

const testA = await fetchToken(testAAddress, chain, web3)
const testB = await fetchToken(testBAddress, chain, web3)
const fee = 2000 // 2000 means 0.2%

// fetch limit order
const {activeOrders, deactiveOrders} = await fetchLimitOrderOfAccount(
    chain, web3, limitOrderManager, '0xD0B1c02E8A6CA05c7737A3F4a0EEDe075fa4920C', [testA]
)

the code above is nearly the same as fetch limit order, you can view more detailed explains though this link

2. select an order and get calling of decrease

first, select an order or your own

const activeOrderAt2 = activeOrders[2]

second, get calling for decreasing the limit order

const orderIdx = activeOrderAt2.idx
const gasPrice = '5000000000'
// dec limit order of orderIdx
const {decLimOrderCalling, options} = getDecLimOrderCall(
    limitOrderManager,
    orderIdx,
    activeOrderAt2.sellingRemain,
    '0xffffffff',
    account.address,
    chain,
    gasPrice
)

3. estimate gas (optional)

of course you can skip this step if you don’t want to limit gas.

const gasLimit = await decLimOrderCalling.estimateGas(options)

4. finally, send transaction!

for metamask or other explorer’s wallet provider, you can easily write

await decLimOrderCalling.send({...options, gas: gasLimit})

otherwise, if you run codes in console, you could use following code

const signedTx = await web3.eth.accounts.signTransaction(
    {
        ...options,
        to: limitOrderAddress,
        data: decLimOrderCalling.encodeABI(),
        gas: new BigNumber(gasLimit * 1.1).toFixed(0, 2),
    },
    privateKey
)
// nonce += 1;
const tx = await web3.eth.sendSignedTransaction(signedTx.rawTransaction);

after this step, we have successfully decrease a limit order (if no revert occurred).