Transfer ERC20 token

The api is POST api: api/v3/transfer

You can also refer to js sdk: https://github.com/Loopring/loopring_sdk/blob/master/src/tests/transfer.test.ts#L110

Here are some main flow about how to transfer an ERC20 token in layer2.

1 get fee

GET api: api/v3/user/offchainFee

transfer: requestType is 3

header: 
X-API-KEY = bEef7a3Nzk7lgaHm85E0O1JO5ufu0iQ96p3bCmrsZz8TLGG83jTpPDYwcjUC0vlF

request:
https://uat2.loopring.io/api/v3/user/offchainFee?accountId=11329&requestType=3&tokenSymbol=0x0000000000000000000000000000000000000000&amount=2000000000000

response:
{
    "gasPrice": "2194508101",
    "fees": [{
        "token": "ETH",
        "fee": "1920000000000",
        "discount": 1
    }, {
        "token": "LRC",
        "fee": "4770000000000000",
        "discount": 0.8
    }, {
        "token": "USDT",
        "fee": "2190",
        "discount": 0.8
    }, {
        "token": "DAI",
        "fee": "2730000000000000",
        "discount": 1
    }]
}

2 get storageID

GET api: api/v3/storageId

header: 
X-API-KEY = bEef7a3Nzk7lgaHm85E0O1JO5ufu0iQ96p3bCmrsZz8TLGG83jTpPDYwcjUC0vlF

request:
https://uat2.loopring.io/api/v3/storageId?accountId=11329&sellTokenId=0

response:
{
    "orderId": 0,
    "offchainId": 1
}

3 submit transfer

POST api: api/v3/transfer

storageId: the response in get storageID

maxFee: the response in get fee

payeeId: set to 0 is ok

https://uat2.loopring.io/api/v3/transfer

header: 
X-API-KEY = bEef7a3Nzk7lgaHm85E0O1JO5ufu0iQ96p3bCmrsZz8TLGG83jTpPDYwcjUC0vlF
X-API-SIG = 0xf4f902bffcdc2e640efe8f86ef970b65bea4ad1312e8ab33b200852d87a0fd881a584e201b52d768f333eb39b084ccde42dfe110fb683b81319837c6e92fa2691c03

request:
{
    "ecdsaHash": "0xa8023b3765fc5aa05ef578645f9ec45d9208427ff34a57d40257d7c4403fe39c",
    "ecdsaSignature": "0xf4f902bffcdc2e640efe8f86ef970b65bea4ad1312e8ab33b200852d87a0fd881a584e201b52d768f333eb39b084ccde42dfe110fb683b81319837c6e92fa2691c03",
    "eddsaHash": "0x099301b1acb2634f1ea3f15e14ab078a054a1dee69c60b2f60ce7350eccd217b",
    "eddsaSignature": "0x200659c0a16e58e1fe5be034fd7e8f79e819c1464037f7b75c1e58b565e26f021bc97487c02411fbde4b320d06ea270c1b0fdf92e53a503ace5602939e6a786502b3c28766cfdedf7420a698fda48aa9899d5a518b15d3ff912d2a89942ecd07",
    "exchange": "0x2e76EBd1c7c0C8e7c2B875b6d505a260C525d25e",
    "maxFee": {
        "volume": "1920000000000",
        "tokenId": 0
    },
    "memo": "",
    "payeeAddr": "0x8656920c85342d646E5286Cb841F90209272ABec",
    "payeeId": 0,
    "payerAddr": "0x8656920c85342d646E5286Cb841F90209272ABeb",
    "payerId": 11329,
    "storageId": 1,
    "token": {
        "volume": "2000000000000",
        "tokenId": 0
    },
    "validUntil": 1644929199
}

response:
{
    "hash": "0x099301b1acb2634f1ea3f15e14ab078a054a1dee69c60b2f60ce7350eccd217b",
    "status": "processing",
    "isIdempotent": false
}