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Integration
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Security
Using Tellor
Updating Values
Checking Last Update
Before calling a function to update your values, you should first just check if it's already there! Tellor values, once onchain, are free for anyone to read. This means that if someone else just updated the value, you can use it free of charge!
To check when the value was last updated, you can run the following usingTellor function:
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function getCurrentValue(bytes32 _queryId) public view returns (bool _ifRetrieve, bytes _value, uint256 _timestampRetrieved);
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The last returned value is the most recently updated timestamp.
Adding a Tip
If the time the value was last updated is not sufficient, you can add a tip to your queryId in order to get it reported.
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function tipQuery(bytes32 _queryId, uint256 _tip, bytes memory _queryData)
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Tellor works by allowing any reporter to submit for any queryId. Each staked reporter just has to wait 12 hours after submitting in order to submit again. It stands to reason that, in order for a reporter to want to submit data, they have to be able to cover their gas costs and then earn a little more on top of that. When adding a tip, you should consider how much a reporter will have to pay in gas to report the data. You can get the current reward for a queryId with the following function, which returns the tip amount first, and then the time based reward:
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function getCurrentReward(bytes32 _queryId) public view returns(uint256, uint256)
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Monitoring Values and Disputing
Once values are on-chain, we recommend you don't just take them right away. Tellor has a robust network of reporters and watchdogs that are valiantly checking and ensuring accuracy, but the best person to know if your data is correct is you.
You can monitor values and submit disputes by reading the value on-chain:
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function getCurrentValue(bytes32 _queryId) public view returns (bool ifRetrieve, bytes value, uint256 _timestampRetrieved);
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function beginDispute(bytes32 _queryId, uint256 _timestamp) external
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Dispute fees may be costly, but are returned (along with a stake reward) if the dispute is valid.
Once the dispute goes through, be sure to request your data again so the reporters have another chance to push through a valid price.
Parsing Bytes
All Tellor oracle values are stored in
bytes format. If you need your data in uint256 format, you can parse bytes using a function like the one below:1
function _sliceUint(bytes memory _b) public pure returns (uint256 _x) {
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uint256 _number = 0;
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for (uint256 _i = 0; _i < _b.length; _i++) {
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_number = _number * 2**8;
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_number = _number + uint8(_b[_i]);
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}
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return _number;
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}
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If you need data parsed in a different way, see this article or reach out to the Tellor team for guidance.
Full Example
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// SPDX-License-Identifier: MIT
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pragma solidity 0.8.3;
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import "usingtellor/contracts/UsingTellor.sol";
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contract ExampleContract is UsingTellor {
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// _tellorAddress is the address of the Tellor oracle
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constructor(address payable _tellorAddress) UsingTellor(_tellorAddress) {}
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function getBtcSpotPrice() external view returns(uint256) {
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bytes memory _queryData = abi.encode("SpotPrice", abi.encode("btc", "usd"));
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bytes32 _queryId = keccak256(_queryData);
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// Tip: Use UsingTellor's getDataBefore(bytes32 _queryId, uint256 _timestamp)
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// function with a buffer time (1 hour for example) to allow time for a bad value
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// to be disputed
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(bool ifRetrieve, bytes memory _value, ) =
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getDataBefore(_queryId, block.timestamp - 1 hours);
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if (!ifRetrieve) return 0;
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return _sliceUint(_value);
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}
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// All Tellor oracle values are stored in bytes format. If you need your data
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// in uint256 format, you can parse bytes using a function like the one below
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function _sliceUint(bytes memory _b) internal pure returns (uint256 _x) {
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uint256 _number = 0;
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for (uint256 _i = 0; _i < _b.length; _i++) {
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_number = _number * 2**8;
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_number = _number + uint8(_b[_i]);
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}
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return _number;
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}
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}
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Automating Jobs
To automate adding a tip on a certain query ID by time or volatility, as well as scheduling other Tellor related tasks, we recommend (and use) Buidlhub.
Last modified 1mo ago