Example Oracle Rental Contract (Chainlink)

This is an example Solidity contract that simulates a simple rental use case using Chainlink nodes to fulfil oracle requests.

Use Case

A monthly rental amount of 0.01 ether will be payable on the 1st working day of every month (1WDOM). The 1WDOM is something a smart contract cannot determine itself, so it needs to communitate with an oracle (via a Chainlink node) to get this information. The node uses the Off Chain Data API for working day information.

Note

• By default, the contract wont burn ETH to simulate rental payments. If you want to change this behavior, then you must set the performBurn property to true.
• Rental payments are sent to a burner address.
• The contract must also be funded with LINK tokens to make payments to the oracle. Use this faucet to obtain Ropsten test LINK tokens.
• You can change the monthly rental amount by calling setRentalAmount()

Setup

• Clone this repository
• npm install
• truffle test

Deployment & Usage

• Run truffle-flattener contracts/RentalContract.sol > RentalContract.dist.sol and copy the contents of RentalContract.dist.sol to Remix.
• When deploying to Ropsten you can use then LINK and Oracle addresses listed in the comments of the contract's constructor.
• Below is an example of arguments to use in the call to checkDate(). The 1st argument is the Job Id which tells the node what data to return. You can use the Job Id listed in the comments of the checkDate() method.

Calling checkDate() will issue a request to the Oracle. Once the oracle returns data (which can take a few minutes), the fulfil() method will be called. If your requested date is a 1WDOM, the monthly rental amount will be deducted from the contract's balance.

• You can inspect what was returned by Oracle by looking at the businessDayOfMonth and paidDates member variables.

You will need to convert your date string to the Bytes32 version using a tool such as https://blockchangers.github.io/solidity-converter-online/

If you just want to play around with an already deployed contract, you can use the one found at this address 0x64d6a7d69d5121490a5f99daf6c17294b041675c