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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What is the verification process of nodes on chainLink?

chainLink is a decentralized system similar to Ethereum, which can help smart contracts execute get requests and return the results. The result of chainLink execution also needs to be verified by ...
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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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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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3 votes
2 answers
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Generating random number in Solidity without Chainlink

Hello I'm well aware there are plenty of threads around discussing different methods. Just curious and wanted to ask directly here because feel like the situation might be different. Essentially I'm ...
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Advantage of Chainlink's VRF over commitment scheme chain

News Chainlink announced a randomness oracle via VRF: https://blog.chain.link/verifiable-random-functions-vrf-random-number-generation-rng-feature/. Question What is the advantage of an VRF over a ...
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2 votes
1 answer
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Solidity timeout error Remix Chainlink interface Rinkeby

I am following Patrick Collin's smart contract course on youtube and am stuck at the 2hr 46min mark (FundMe.sol) ETH/USD Chainlink price feed on rinkeby. The code from the video compiles ok but when i ...
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155 views

Need help for extracting historical prices using chainlink api

This is my first time i am using a api call for implementing on project for predicting the avalanche price feed for machine learning to get the historical data for 2 years. I want api call from ...
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18 views

Basic function returns 0x0000000000000

I'm trying to learn Soliity and started with a basic api. I pass the parameters of the function (from here I got the format of the parameters https://market.link/nodes/5fcd7b71-33aa-4679-bc70-...
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Best way to get notified when fallback arrived

When you request random number, the Chainlink VRF2 returns it by calling following function. function fulfillRandomWords( uint256, /* requestId */ uint256[] memory randomWords ) ...
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Chain Link oracle : Fail with error 'First word must be requestId'

I just span up an oracle contract using "@chainlink/contracts/src/v0.7/Operator.sol"; I am using Operator.sol specifically for the fulfillRequest2 function since i need to return data in the ...
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Chainlink Oracle : Fail with error 'Must have a valid requestId'

Facing a slight issue with my Oracle.sol that I deployed for my Naas node. whenever its fulfilling the request back to the contract, it throws this error. I deployed the contract using "@...
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Chainlink: how to get an array of random numbers?

I'm using Chainlink VRF and its function to get an array of random numbers: function expand(uint256 randomValue, uint256 n) public pure returns (uint256[] memory expandedValues) { expandedValues = ...
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How to put msg.sender into a string?

In my smart contract I need to put the sender's eth address (msg.sender) into a string. I have this request code (I'm using Chainlink): request.add("get", "https://APIURL/functions/...
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Specifying `path` for multi-variable responses with Chainlink

I am trying to understand the documentation for making multi-variable requests with Chainlink (docs), and something that is unclear is how to specify how the multiple values are queried. With the ...
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how to enable local connection of chainlink?

I have a custom API running on http://127.0.0.1:8080 and I have my own chainlink node running on http://127.0.0.1:6688. I get the error saying "Connections to local/private and multicast networks ...
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How can I make multiple keeper feeds?

Since we have more than one keeper model, we have keeper to feed these keepers. This keeper feeds himself at the same time. When determining the keeper balance, we set it as "x" multiple the ...
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Chainlink job returning previous pipelines to external initiator after bridge call

I have a job in my chainlink node that is described as follows: type = "webhook" schemaVersion = 1 name = "essevai2" externalJobID = "xxxxxxx" observationSource = "&...
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137 views

VSCode and parser not recognizing import statements

When I try to use brownie to compile my solidity code on VS Code using brownie compile, it throws an error, saying my contract should be labeled as an abstract. However, the parser is not recognizing ...
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Chainlink node setup - "Failed to run migration 0003_eth_logs_table"

When I try running cd ~/.chainlink-rinkeby && docker run -p 6688:6688 -v ~/.chainlink-rinkeby:/chainlink -it --env-file=.env smartcontract/chainlink:0.10.14 local n I receive the following ...
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Chainlink job not working with external bridge, it is giving an error "Error: UnprocessableEntityError"

I have created an external adapter and hosted it on AWS server as it required to get data from third part URL with authentication headers. I have also hosted a chainlink node and added this AWS ...
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57 views

How to walk down an API when making a chainlink get request?

Am trying to make a chainlink Get>Bool httpget request on the fantasy premierleague API but keep getting a false response. my code is: ''' function getGwstaus() public returns (bytes32 requestId) ...
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Locally test Chainlink VRF call from another contract in Waffle/Hardhat

Locally testing Chainlinks VRF While trying to locally test a contract that calls a Chainlink VRF contract, I'm experiencing some difficulties in setting up the contract balances. I have a ...
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2 answers
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Chainlink historical price for AggregatorV3Interface

Similar to this question How to get all the historical data from chainlink price feeds? I would like to retrieve the historical data of a particular price feed to be used off-chain for a large number ...
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1 answer
664 views

How to validate the Chainlink price feed at a specific time

Suppose that in my solidity contract, I need to see the price of ETH in terms of USD at a specific time, say on January 1, 2021. I would like to use the Historical Price Data Feed from chainlink (URL ...
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170 views

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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98 views

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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1 answer
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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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15 views

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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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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59 views

Unable to get response back from chainlink node using truffle console

I am trying to fetch close prices of a property deployed on a server running on a chainlink node. Here's what a snippet from my contract (RealEstateAPIConsumer.sol) looks like : function ...
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event from ChainLinkClient does not emit properly

The events emitted from the requestRobotUrlBytes function which is directly called by me seems to work fine but those emitted from fulfillBytes which is called by the oracle are not emitted. I'm using ...
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Is there a way to get history of transaction of specific smart contract using chainlink?

Here is my use case I have a smart contract that emit an event . I am new to chainlink , so my question if someone know how I can track that event history with its data using chainlink. Thanks
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15 views

Can we have communications in a web-based dapp?

I want to create a ui with web3js for some etherium smart contracts. However, I like to enquire the wallet owners whether or not they will accept the transaction Is it possible to send them some sort ...
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Is there a way to import LinkToken, MockV3Aggregator, and all the other Chainlink mocks without adding the interface file?

I'm following the Solidity, Blockchain, and Smart Contract Course lessons from Free Code Camp and I noticed that Patrick sometimes seems to import mock Chainlink aggregators and mock token contracts ...
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30 views

How chainlink oracle works incase of state update?

I was trying to understand this pizza sample build by Patrick Collins. so my understanding is that when we send a transaction (for example store which stores a user provided number) all the nodes in ...
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1 answer
17 views

If Chainlinks price feeds are free to consume, what is the point of requesting data directly from node operators?

If Chainlinks price feeds are free to consume, what is the point of requesting data directly from node operators which would cost LINK? Do platforms such as DEXs or lending platforms like AAVE pay to ...
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Update last keeper when is triggered chainlink keepers

Have some troubles with chainlink keepers. I registered a keeper herehttps://keepers.chain.link/kovan/2974, but it`s not triggered and last keeper field is empty. I set the interval to checkUpkeep. ...
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1 answer
38 views

How to build Chainlink request so that the response will be sent to another contract?

I am currently exploring the Chainlink API Consumer smart contract that brings off-chain data to the smart contract through GET request. There is an understandable example of how to perform such task. ...
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1 answer
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How Chainlink VRF fulfillRandomWords() callback function works?

I am using Chainlink VRF2 where I receive random numbers via a callback to this function: function fulfillRandomWords( uint256, /* requestId */ uint256[] memory randomWords ) internal ...
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Can I get a hash of an HTTP response body through ChainLink Any API

ChainLink Any API docs tell me how to send GET requests and parse JSON results, then send a small part of the response to my contract. Is there a way to receive a hash of all the response body, or ...
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Returning structs from Chainlink oracle job

Is it possible to return struct from chainlink oracle job? I would like to return list of transactions from chainlink job to the contract. So far I've only seen examples where it's possible to return ...
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Getting " Gas estimation failed" error for pet project - "smart_lottery_contract" project

I am new to blockchain and I am following the tutorial by Patrick based on the project I have my code here at :https://github.com/shashankvivek/blockchain/tree/main/smartLottery_contract_revisited ...
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23 views

Opensea shows airdrop when randomnize token id

I'm minting the nft with random token but Opensea showing "airdrop" in transaction history. I want to keep this minted. help me please. function mint() public payable { require( ...
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SafeMint in fullfillrandomness function [Chainlink]

It's not working function mint() public payable { require( LINK.balanceOf(address(this)) >= fee, "Not enough LINK - fill contract with faucet" ); ...
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revert InvalidCalldata error VRFCoordinator

I am using a clone of the pancakeSwap lottery and attempting to use a write function. I keep getting an error in the BSC testnet VRFCoordinatorV2 contract saying revert InvalidCalldata();. The ...
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44 views

How to achieve verifiable randomness on Polygon, Avalanche, Arbitrum, etc...?

Chainlink VRF is only available on Ethereum and BSC so how does protocols on other chains achieve randomness?
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34 views

Questions about the fulfill function in the Chainlink API Call tutorial

I was going through the Chainlink tutorial on APIs and had some questions about the fulfill function in the contract below. From how I understand it, the third argument of request object inside the ...
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1 answer
30 views

Events in Chainlink Keepers checkUpkeep() not emited

I created a bare bone Chainlink keeper for testing purpose. In checkUpkeep, I set upkeepNeeded to true and emit an event. In performUpkeep, I increment a counter and emit another event. Surprisingly, ...
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1 answer
77 views

chainlink oracle http get request not returning value - taken from example but still is not working

I have my own oracle code that suddenly stopped returning any output. So I double checked with the official Chainlink oracle example on remix and that is also not returning any value... I have sent ...
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17 views

why chainlink job errored with jsonparse array of path

I'm trying to read information from an api using a chainlink node. However, I came across an error that I couldn't resolve. jsonparseError: could not resolve path ["assets.0.id"] in {"...
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