Linked Questions

0 votes
0 answers

Smart Contracts and BigchainDB

How can I access data stored in blockchain database like BigchainDB using a smart contract in Ethereum?
Suvam Tamang's user avatar
0 votes
1 answer

How to pass NFT property value to smart contract

I have an NFT staking contract that issues rewards based on the property rarity of the NFT staked. The four property tiers are 1,2,3 and 4. When a user clicks stakeNFT(tokenId, nftTier), I use the ...
John Smith's user avatar
0 votes
0 answers

How to get "dna" from the metadata file of a ERC721 token in Solidity

here is the context, I would like to be able to burn n ERC721 token based on the "dna" and the attributes "type" in the metadata (see below): { "dna": "602472F&...
Remzzer's user avatar
  • 25
0 votes
0 answers

How do i get the price of an erc20 token from solidity smart contract [duplicate]

I'm building a dapp, i'm trying to get the erc20 token price in usd from my smart contract how do i go about this? this is very necessary as smart contracts cannot read from outside networks. I don't ...
Benjamin's user avatar
5 votes
3 answers

Can we use block hash as verifiable randomness for the off-chain lottery?

My team is writing a discord lottery bot, we want to use the block hash of some block in the future as a seed for the random generator. We want to allow lottery participants to independently verify ...
Artem Bernatskyi's user avatar
1 vote
1 answer

Retrieve Uniswap tx data in my solidity smart contract

As the title says, I have my Solidity smart contract and I am trying to import in ti some public data from the Uniswap contract. In particular I would like to have the tx data stored in my contract (...
4NDR34's user avatar
  • 61
10 votes
3 answers

Flash loan security considerations and attacks

What do developers need to be aware of to make their contracts and systems safe against flash loans? What do they have to think about and protect against?
eth's user avatar
  • 85.8k
1 vote
1 answer

Getting stock market data from API or other means?

I'm trying to make a contract that interacts with a market price or a market out come : e.g APPL drops below X or NFLX > Y ... Is it possible in Solidity to call an external API during this ...
user491880's user avatar
2 votes
3 answers

Decentralized database for ethereum?

I'm looking for a way to store data in a decentralized way such that I can access any record from within the smart contract, probably through oracles I guess? I've been looking into gundb but not ...
Sc4R's user avatar
  • 75
6 votes
3 answers

What is the Oracle Problem definition exactly and briefly?

What is the Oracle Problem definition exactly and briefly? Does it mean "trusting on a centralized Oracle" ? Or "How to reach a consensus between a group of Oracles" ? Is the matter "centralization" ...
Questioner's user avatar
  • 2,670
5 votes
4 answers

Can I make 'wait n seconds' statement in solidity function? [duplicate]

I want to write a solidity function like function func(uint n, parameters*) payable public { ""wait n seconds"" other statements } Is it possible? It seems that delay parameter in ...
Guldam Kwak's user avatar
3 votes
2 answers

How to set dynamic buy and sell price for my token?

I have built a simple erc-20 token. I used the code given on code as a reference. There they have talked about setting the price of my token. But how do I set it dynamically, as in ...
sushantmit's user avatar
5 votes
2 answers

Is there a way to get the *current* price of ETH in solidity function?

Is it possible to get the current price of ETH in USD in a buyTokens function of a deployed solidity smart contract? For instance, every time GETH starts up is determines the price of ETH during ...
wardsback's user avatar
  • 399
4 votes
1 answer

How to find out the rate of ETH in USD in the contract?

I have a function which can rate ETH in USD. How can I find out the rate of ETH in USD in automatic mode? Can this be done in Solidty? Or do I have to use a third-party language, for example, ...
blanry's user avatar
  • 93
19 votes
2 answers

How to access external knowledge / data in a smart contract

let’s say a contract wants to execute on knowledge contained outside the blockchain (e.g. whats the price of gold, what was the avg windspeed in NYC, how many people moved to portland in the last ...
dougvk's user avatar
  • 293

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