Simple Crowdsale

In this chapter we will hold a crowdsale using the contracts from Vevue's ICO. It is essentially an ERC20 token, with the addition of an buyTokens method. When a user sends money into the contract using buyTokens, tokens are minted and credited to the purchaser according to a fixed exchange rate.

The source code for this chapter is at qtumproject/qtumjs-vevue-ico.

There are a few hard codeed parameters in the token contract, and you could tweak them to suit your particular token design.

Some of the contract parameters are:

  • decimals: How "divisble" one unit token is.

    • 8 decimal places, to be as divisible as Bitcoin. The smallest unit is satoshi.
  • tokenTotalSupply: The maximum token supply.

    • 100M tokens in total.
  • saleAmount: amount of tokens to sell.

    • 40M tokens for sell
  • _initialExchangeRate: the exchange rate.

    • Set to 1 qtum for 100 tokens.

For simplicity, we disabled the start and end time of the crowdsale (specified in block number).

Without further ado, let's launch our crowdsale!

Create An Owner Address

Let's generate an address to be the owner of the contract. The crowdsale proceeds will go into this address.

qcli getnewaddress

qcli gethexaddress qJtdUF9ko4Hk95cqTzq7SDs18dapNwjRNS

Send some fund to the owner address pay for gas:

qcli sendtoaddress qJtdUF9ko4Hk95cqTzq7SDs18dapNwjRNS 1

Then we should configure solar to use this address when we deploy new contracts.

export QTUM_SENDER=qJtdUF9ko4Hk95cqTzq7SDs18dapNwjRNS

Deploy The Token Contract

Use solar to deploy the contract:

solar deploy VevueToken.sol --force

🚀  All contracts confirmed
   deployed VevueToken.sol => 09b97cc71a300f1bdad44711f4ce9f25bd404d8b

Verify that the contract owner is the QTUM_SENDER address that we've set before:

solar status

✅  VevueToken.sol
        txid: 08528ef006f05fdfe1d6eb3006bac7dfc21d6f854822081575b9ff8b61950cdd
     address: 09b97cc71a300f1bdad44711f4ce9f25bd404d8b
   confirmed: true
       owner: qJtdUF9ko4Hk95cqTzq7SDs18dapNwjRNS

Initial Crowdsale State

We can use the included qtumjs script to print out information about the crowdsale:

node index.js info

supply cap: 100000000.00000000
sales cap: 40000000.00000000
current token supply: 0.0
tokens sold: 0.0
  • Verify that the supply and sales cap are as specified

    • There are 8 decimal places
  • The current supply is 0

Buy Tokens

Let's generate another address and use it to receive the purchased tokens:

qcli getnewaddress
qcli gethexaddress qgMR2N4ANuswodFh8T4gYMD3a3VNAd11Jt

Now, spend 1 qtum to buy tokens (geting 100 tokens in return):

node index.js buy fa0775ed07771e390c5a3bd2f00cef05bc4185f2 1

After the tx confirms, the token's supply should have incremented by 100:

node index.js info

supply cap: 100000000.00000000
sales cap: 40000000.00000000
current token supply: 100.00000000
tokens sold: 100.00000000

We can also check that the particular address we bought the tokens for have received the correct balance:

node index.js balanceOf fa0775ed07771e390c5a3bd2f00cef05bc4185f2

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