How can I get lists of ERC20, ERC721 and ERC827 tokens in a particular Ethereum wallet address? Also I would like to be able to get the name, symbol, logo, and balance from the main net.
ERC-721 includes an optional interface (optional means the contract implementor can choose if they want to implement it) to enumerate tokens owned by a specific account.
Su Squares implements this feature, but few other contracts do it.
You can use tools like Etherscan, Enjinx Blockchain Explorer or write your own interface to a Ethereum JSON RPC host to collect the data.
I don't think you can do a total data dive per address. I think you have to go the other way around, meaning looking if a contract contains a certain token. For the major tokens like EOS, this should be easy with MEW.
But if you're looking for some obscure tokens such as the ones below, you probably have to add them to MEW manually to check:
Crap Coin (CRP)
Ingrid Is a Horrible Human Coin (iHH)
Banana Coin
Related
I am planning to issue erc20 token on ethereum and I want to use it as a payment for dapps on polygon.
How may I estublish the interaction between the contracts? A potential answer to that question might be bridging. But I tried to look for every platform to understand, how can I use my coin tokens after bridging, but failed to find any definite answer.
so my question is, if two contracts are on the same chain-
IERC20 token = IERC20(some_address);
We use the above line to call our coin token from our dapp. Since, our coin token is on different ethereum chain, after bridging, how do we call it feom a contract that will be deployed on polygon?
Will the above line of code work? Will I get a new address on polygon for my token contract?
(Recently I have seen a technique, but couldn't understand the underlying mechanism. So, there is a website called Coinvise, they let you deploy your coin airdrop contract on polygon and let you set the nft address (to know if user holds that particular nft) as eligibility condition that is deployed on ethereum. They do it on chain using something called 'sub-graph'. I do not know what this is but I'd like to know if it helps in my case.)
I am new to blockchain, please help
I'm building a DeFi application on Ethereum, and I would like to implement the Deposit function. Everything works fine between ETH and a ERC20 token that I built, but I would like to add some tokens like aToken for AAVE or cTokens for Compound that the user will receive after a Deposit call.
So the question is: is it possible to add a function in my smart contract to create multiple tokens without creating a smart contract for each of them? If not, I have to create a different contract for each token I want to add in my app or there is a best method to do it?
Yes this is possible. You can transfer the tokens to the user's address after the Compound Protocol mint operation. This can be made generic using the ERC-20 transfer interface. Be sure to account the amounts users are due and beware of the reentrancy vulnerability.
Can NFT's be used as a mean of authentication? The scenario is a user buys an NFT (ERC721) now he visits the site that uses this Token for authentication, so am guessing the web3.js on the site checks the users wallet if he has the token in wallet then can access the site....but what about server side calls...the server can check the ledger to see who owns the token, but how can it know if the person making the call is the owner..address can be spoofed so sending it with call is out of question. Also the case if users sells his token now a new user owns it
Am thinking something like digital signature but how to get the owners public key and is requiring users to sign messages a hassle...am noob to solidity what do I know but SO requires me to try to answer my question before asking for an answer also some code a requirement for every posts
pragma solidity ^0.4.22;contract helloWorld {
function renderHelloWorld () public pure returns (string) {
return 'helloWorld';
}
}
Checking that the viewer has an address that owns the token is not enough. You would need to confirm that the viewer controls the address by asking them to sign a message.
One system like this is called MetaKey.
If you want to coordinate sessions with a backend, you need to do additional work because the NFT could be transferred. You would need to revoke the session key when the NFT is transferred, which requires that you monitor the blockchain for transfer events.
I don't recommend building sign in infrastructure around an NFTs though. It will be extremely difficult or impossible to avoid security flaws. Better to authenticate people using a wallet signature. There are many tutorials online for building this flow, for example here.
If you are using the ERC-721 standard, what is the prefer method determining which tokens the address owns in a DAPP.
Currently I'm request all the Transfer Events for an address and basically sorting them into transfer in and transfer out, and then using that to determine which tokens the user owns.
Is there a simpler way I missed.
Transfer events may be emitted also by contracts that are not ERC-721 tokens, or some noname tokens that you might not be interested in.
The actual token ownership is stored in the tokens contracts (and not the DAPP contract).
So your current approach is pretty much as straightforward as it can get, if you want to automatically keep track of all tokens that the address currently owns (and some false positives as well).
Note: This is also similar to the approach of Etherscan, which listens to all Transfer event logs and if the sender contract is listed in their database of tokens, they use the event log data to update balances of the sender and recipient.
If you're willing/able to create and maintain a list of tokens that you want to follow, I'd recommend a simpler approach:
Define the list of followed token contract addresses (e.g. ECF or RARI)
For each of these token contracts, call balanceOf(<your_dapp_address>) that returns amount of tokens that the <your_dapp_address> currently owns.
Everyone can create ethereum token by solidity codes but don't know how can this token integrate as payment gateway in ecommerce website.
For real project . This token need frontend web wallet /android wallet and integration to every website as payment.
Plz suggest me .how can find this way.
What need more to study.
Token is not a payment gateway. If i understand your question correctly, you are asking, how can you interact with a token that you have created through Solidity from frontend. One use case would be how people can use the token that you have created to purchase some item. For this the users should already be holding the tokens. This can be bought from an ICO or from an exchange. Basically there's a couple of functions in ERC20 token i.e., approve() and transfer() that will approve apps like exchanges to perform transactions on behalf of the owner of the token. Once the users have those tokens they can purchase items from it. Again, you have to write the logic how and what you expect users to do.
ERC20 Token is works likes Currency.And solidity is a programming language. which we used for write the smart contract. if you want to invoke your function then you need to create wallet account ,after that you can do transaction using with web3js. you can get ether for testing purpose from faucet.Basically these are functions in ERC20 token i.e., approve() and transfer() that will perform transactions
I don't suggest using ERC20 tokens as payment method.
Ethereum network is not fast enough,you need 30 confirmations to make sure you received the token, some times the delay can be 1 day
Cost is high, when you transfer token ,usually you have a smart contract, it costs lots of gas
Ether price is not stable, it drops 90% of value from Jan 2018 to Dec 2018. it will be hard for estore to maintain profit.
However if you still want to do that, yes, you can create your own gateway using tokens as your accepted currency.