Questions tagged [chainlink]

Chainlink is a decentralized oracle network that enables blockchain smart contracts to securely access off-chain data feeds.

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Not receiving LINK from Chainlink kovan faucet

I attempted to get funds from kovan.chain.link to my metamask address and the money did not come through. I got some errors as seen here: https://kovan.etherscan.io/tx/...
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I had a error like : ParserError: Source file requires different compiler version , while using Chainlink&OpenZeppelin

I'm trying to implement PatrickAlpha NFT-mix implementation (Github link) . When I followed readme instructions, collectibles are minted correctly. But If I tried to change anything in the code , it ...
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How to return a Chainlink API Call to another contract?

I need to call a function that returns the uint value requested by the oracle from another contract function. I am trying the next... but I think I am going by the bad way. Any solution for that? The ...
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How to make a ChainLink solidity oracle asynchronous call?

I need to introduce a uint in my Ethereum contract. I am testing this code in Kovan in base to this example: https://docs.chain.link/docs/make-a-http-get-request/ pragma solidity ^0.6.0; import &...
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Why is this particular line of code stopping the smart contract from being deployed?

I am coding a smart contract which will be integrating ChainLink's decentralized oracles, however I've run into an issue that is preventing me from deploying the smart contract on Remix IDE. The ...
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How to build a decentralized bridge between two blockchains?

I am trying to build my own custom bridge between Ethereum and Binance Smart Chain so that people can transfer tokens and possibly some other assets from one chain to another and vice versa. For this ...
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2 answers
525 views

What is the best way for a smart contract to constantly listen to a price feed and execute immediately once the price is reached?

I have compiled a smart contract that is supposed to take bets from 2 addresses, a bet creator and a bet taker. The bet is on the price of ETH/USD (via ChainLink). What would be the best way to for ...
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how chainlink aggregates

How does chainlink result aggregation work? Are all oracle nodes that user-specified reports the results to the smart contract that chainlink is submitted on Ethereum? Is taking a median off ...
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How to detect false data feed from Chainlink oracles

I understand Chainlink uses explicit and implicit staking to enforce honest behavior. However, what is the mechanism used to catch the misbehavior of oracles (i.e., reporting wrong data)?
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Chainlink oracle vs node vs node operator

What are the differences or similarities betweent the chainlink oracle and node and node operator? Is oracle equal to node that runs on chainlink network?
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ChainlinkClient.sol v0.8.0 NOT working (request.add("get", "<url>"))

Im am relatively new to using ChainLinks ORACLE contract in solidity. I have recently managed to successfully integrate their VRFConsumerBase.sol in my consumer contract to generate random numbers. ...
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I am trying to use chain link using remix

I'm getting this error /* Internal exception in StandardCompiler::compile: /root/project/libsolidity/interface/CompilerStack.cpp(93): Throw in function solidity::frontend::CompilerStack::CompilerStack(...
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I am trying to use chainlink using remix and i followed the chainlink docs

I am facing this issue,What to do now? My Code pragma solidity ^0.6.7; import "https://github.com/smartcontractkit/chainlink/blob/master/evm-contracts/src/v0.6/interfaces/AggregatorV3Interface....
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Can I get price feed information directly from ChainLink oracles rather than from the aggregated contract?

I've been experimenting with ChainLink recently and am fascinated of what it can do. I already used the code provided here ChainLink Docs in Python and got it to work. However, I've been searching all ...
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price conversion using chainlink ETHUSD price

I'm storing a product's USD value in contract. mapping (string => uint256) productUSD; For example, if it's $52 I'd store it as productUSD[_product] = 52; Now, when people paying in ETH, I want to ...
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ERC20 token balance = 0 in MetaMask

While setting up a test ChainLink node on Rinkeby, I sent some test LINK to my address. The ChainLink web interface showed a balance of 0 LINK. So I checked EtherScan. The transaction succeeded and ...
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Issue with importing Chainlink & Openzeppelin

Currently trying to run a script and keep running into an error when trying to import chainlink and openzeppelin contracts. Not sure why, I looked at brownie pm list to make sure I have the correct ...
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4 votes
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How can I protect my Chainlink oracle fulfill method?

Background: I'm writing a contract that inherits ChainlinkClient in order to make an API request via an oracle job: function fetch() private returns (bytes32 requestId) { Chainlink.Request memory ...
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ERROR: null value in column "next_nonce" violates not-null constraint (SQLSTATE 23502)

I am using this command to run my chainlink node: docker run --name chainlink-kovan --network host -p 6688:6688 -v ~/.chainlink-kovan:/chainlink -it --env-file=.env smartcontract/chainlink:0.10.3 ...
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What is best approach for generating random NFTs?

I am thinking of developing small DApp where user would collect cards (NFT). Each card would have some image and value associated with it. User collects cards by purchasing Pack of Five Cards which ...
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OZ ERC20 & Chainlink solc compatibility problem

I apologize for the basic question, but I failed to find an answer via websearch & discord. I'm trying to inherit from Open Zeppelin ERC20 which uses solc 0.7. I also need to use Chainlink alarm ...
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2 votes
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400 views

Chainlink node not initializing, failed to initialize ORM: initializeORM#NewORM: unable to init DB: unable to open postgresql

I am trying to setup a chainlink node on my machine. After setting all the .env variables, I am running the docker command to start the node, cd ~/.chainlink-kovan && docker run -p 6688:6688 -...
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Is chain link a stand alone blockchain?

Is chain link a stand alone blockchain or is it a series of smart contracts on the ethereum blockchain?
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Price feed of multiple coins in a single GET request

I have used Chainlink oracle to get the price feed of a single coin. But I want to fetch the latest price of 100s of coins from the smart contract using oracle. Is it possible to get the price of ...
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Chainlink Price Feed - function fails when price not hard-coded but correctly displays in console

I'm experiencing a challenge and hoping for some guidance/help/assist... I've been working on implementing price feed. Testing locally with hardcoded return price works like a charm, no issues. When ...
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Chainlink Alarm Clock fullfill method never called?

Working with the Chainlink Alarm Clock, my fulfill() method seems to never get called. So for the docs example (below), votingLive is never set back to false after time is up. Everything else works ...
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271 views

Can a chain link node listen to ethereum smart contracts events?

Can a chain link node listen to ethereum smart contracts events? Let’s say I want to provide data to a node from a smart contract. Can a I link a chain link node and use a smart contract as an oracle?
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Testing requestRandomness with a unit testing plugin by Remix

when I test rollDice which executes requestRandomness function rollDice(uint256 userProvidedSeed, address roller) public onlyOwner returns (bytes32) { require(wagered.get(roller) > 0, "...
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2 votes
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445 views

fulfillRandomness in Chainlink VRF?

After executing the requestRandomness function function getRandomNumber(uint256 userProvidedSeed) public returns (bytes32 requestId) { require(LINK.balanceOf(address(this)) >= fee, "Not ...
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3 votes
2 answers
414 views

How to run Chainlink Project using eth-brownie python

I had installed eth-brownie using command pip install eth-brownie after Brownie installed.I had bake existing Brownie project into a new directory. mkdir MyChainlinkProject cd MyChainlinkProject/ ...
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How to run a chainlink Node on Mac using chainlink source code

I had followed these setups Install Go 1.14, and add your GOPATH's bin directory to your PATH Example Path for macOS export PATH=$GOPATH/bin:$PATH & export GOPATH=/Users/$USER/go Install NodeJS ...
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Acceptable response types with using Chainlink client contract

I want to consume a Github API via the Chainlink Client Contract, the API returns an array of objects wanted to know can that be handled or I need to write a handler?
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Can you recieve inaccurate data from chainlink?

Can you receive inaccurate data from Chainlink blockchain oracles? What if the incentive to distort the data is more than the cost?
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Event data has insufficient length | What does this mean?

I've seen this warning from time to time when working with Brownie Event data has insufficient length This is after I made a call to a Chainlink node, calling a function like: function requestUsers()...
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Funding contract with LINK tokens revert error

When I try creating a Chainlink contract from "master contract" and fund it with LINK, I keep getting the error: "VM error: revert. revert The transaction has been reverted to the ...
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1 vote
1 answer
212 views

Compilation Error while using ChainLink

I am using Remix IDE for my smart contract development. I am using the following import line import "https://github.com/smartcontractkit/chainlink/blob/develop/evm-contracts/src/v0.6/...
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887 views

Make a GET Request over the Binance Smart Chain with a Chainlink Oracle

I am trying to call to an BSC Oracle to make an HTTP request according this ChainLink example. In my example I am goin to use the BSC mainnet 56 and a other JobID obviously: My steps: I created the ...
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2 votes
1 answer
269 views

Can I use chainlink on a private blockchain?

Can I use chainlink on a private blockchain built with Geth? I found that the online tutorials are basically about how to use chainlink on the Kovan test chain. I want to know whether chainlink can be ...
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How does the oracle judge whether the request has been attacked by a man in the middle

The oracle machine can initiate a request to the data source whose URL is the HTTP link address. How does the oracle machine determine whether the HTTP request has been attacked by a man-in-the-middle,...
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EthTx adapter won't respond in Chainlink job, fails with "transaction reverted on-chain"

We're using the standard truffle box (https://github.com/smartcontractkit/box) to deploy Chainlink contract ($LINK definition, Oracle, sample end-user contract, etc) on a private Ethereum testnet. ...
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Solidity finds eth price but its realy big

This script gives me some random like a number and not real eth price? the price that is outputting is 38598000000?! AggregatorInterface internal ref; // For ETH-USD on ropsten, input the address: ...
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9 votes
2 answers
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What are the costs of using Chainlink to generate a random number using VRF?

I'm doing some research about generating true randomness on the Ethereum blockchain. Of course I came across Chainlink and its VRF solution. Although there are many tutorials around, some from ...
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OAuth/BearerTokens in ChainLink

How to add an authentication header for ChainLink API requests? For example, this guide on connecting ChainLink to Twitter API to post a tweet doesn't implement anything of the sort, so how would it ...
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Chainlink - on-chain contract functioning

The on-chain aggregation smart contract for ETH/USD on the mainnet (https://data.chain.link/eth-usd) is at this address https://etherscan.io/address/0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419#code. If ...
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1 vote
1 answer
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Security implementation of a function in Solidity

I'm here for asking some tips on calling function from other contracts in solidity. Here is the function for generating a random number (which I need in the main contract) using the chainlink VRF. ...
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1 answer
261 views

How to pay an Oracle with Link token if I have payable with Ethereum values?

First of all, I'm new to this smart contract world, and so I would like to apology if it's a stupid question. I'm programming with Remix and with Solidity as programming language.I have 2 files: ...
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1 vote
1 answer
60 views

What is the largest number that can be returned from a Chainlink Price Feed?

Is it safe to assume that chainlink oracles have an upper bound on the price feed, eg it fits into uint96, or perhaps a smaller or larger number? It would be great to know the absolute largest number ...
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1 vote
1 answer
845 views

Do all Chainlink feeds return prices with 8 decimals of precision?

It looks like many Chainlink feed aggregators have 8 decimals of precision: ETH/USD, which returns 140330173736 = $1,403.30173736 BTC/USD, which returns 3696759888474 = $36,967.59888474 I found the ...
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2 votes
1 answer
159 views

Does Chainlink have an aggregator for its price aggregators?

I need a way to pass an arbitrary ERC-20 token symbol and get a price for it in return. The Solidity interface should look something like this: function getPrice(string memory symbol) external view ...
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2 answers
2k views

I sent Chainlink Link tokens to my ethereum address, how can I recover? [closed]

By mistake I sent Link tokens to my ethereum wallet (kraken) that can not receive them, can I recover those tokens? How? I think I had to swap them before sending, but I am new, and I think I made ...
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