Questions tagged [erc-721]

Relating to ERC-721, the standard for Non-Fungible Tokens (also known as Deeds)

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Modifying erc-721 transfer

Say I want to take a cut of an NFT each time the token is transferred. If I were to change the openzeppelin erc721 transfer function to transfer 1% of the NFTs holding to myself, can that standard ...
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Functions that are used for token transfers for ERC20 and ERC721 tokens

Let's suppose there is a contract address A of an erc721 token B. If I want to monitor all of its transfers from A to another address say C then should I only filter the Transfer function or should I ...
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35 views

Where can I find full ERC 721 example programs?

I am building a program with an ERC 721 token. My code runs without using the standard components provided by Open Zeppelin IERC721. Now I want to adapt it to the ERC 721 standard. Unfortunately the ...
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1answer
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Read and write private variable from child contract

I have a contract MyContract is ERC721. MyContract needs to concatenate a string with an existing token URI using this function: string(abi.encodePacked(_tokenURIs[_tokenId], _URI)); Problem is all ...
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Enforcing a limit on ERC721 tokens held by an account

We are providing a Gnosis multisig wallets to our users and a market place where users can purchase/sell/transfer ERC721 tokens with other users. The ERC721 contract will also have a Blacklist ...
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Passing constructor arguments from child contract to parent contract

The ERC721 standard contract requires a token name and symbol in its constructor. I have inheritance pattern that looks likes Contract A is B and Contract B is ERC721. If I want to set my token name ...
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1answer
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Why doesn't CryproKitties contract use Enumerable.sol?

I am going through the Cryptokitties code, which does not include the optional Enumerable contract, but the KittyBase contract basically declares equivalent indexation and functions. Why did ...
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1answer
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Identifying ERC-721, ERC-777, & ERC-223 Contracts in the EVM via eth.getTransactionReceipts(), etc

Is there any specific way of identifying ERC-721, ERC-777, & ERC-223 contract events under the EVM, specifically under the eth.getTransactionReceipt() function? I know there's a way for ERC-20 ...
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Possibilities of ERC721 image generation [closed]

What image generation techniques could you suggest for a DApp game that utilizes ERC721? I know that CrypoKitties has a unique DNA sequence and different pieces of the sequence correspond to the ...
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1answer
18 views

When and where do I set ERC721 tokens' data?

I am currently working on a smart contract to sell ERC721 tokens. I understand that my code should have a function that allows me (the owner) to mint a token and add it to a list which stores all the ...
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Does a symbol have to be unique in ERC721? How to find out a unique symbol?

As per the ERC-721 contract on OpenZeppelin, you can create a token with this constructor: constructor(string _name, string _symbol) public {} Does the "_symbol" have to be unique across the ...
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Obtaining ERC721 interface IDs

There's a related question here ERC721: Interface ID Registration but I couldn't get the answer I need from there. In the OpenZeppelin ERC721 basic implementation, there's this part: // Base URI ...
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How to query Cryptokitties metadata from Etherscan

I;m trying to query a Cryptokitties token metadata from Etherscan and I need to give two values: _tokenId (uint256) and _preferredTransport (string). What are possible value for _preferredTransport?
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How do exchanges work internally?

Because EVM cannot watch events, we cannot send a token to an exchange and immediately get back some other token (EVM just does not "know" when it was send a token). As far as I understand, this is ...
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ERC721 Token abstract contract or an interface and cannot be deployed

after reading many post i can't found the issues about this Smart contract who compile but it think i miss something about the inheritance and the Abstract contract. This is the SC : // solium-...
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3answers
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How to issue new ERC 721 tokens for each individuals with different name and symbol

I'm working with an app where different users can create their own ERC721 tokens by passing token, symbol total supply etc. Currently, the code is creating the token, but it has common name only. ...
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1answer
45 views

Which token standard should be use to create different tokens for different users?

I have read several differences between fungible and non fungible tokens. It cleared my few doubts though, I have few more remaining. I have requirement to create a platform on which users can ...
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1answer
68 views

Difference between ERC 20 and ERC 721 transaction receipt

I want to fetch certain transaction logs from a local ethereum node. For that, I need to identify how to differentiate between ERC 20 and ERC 721 transaction receipts. From what I saw on Etherscan, i ...
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1answer
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When to use nonfungible tokens and possibility to interchange tokens with different standards

I'm little bit familiar with Blockchain and ERC-20 standard. Now I started learning about ERC-721 and having a lot of confusion. Let's take an example of music artist token platform. Any music ...
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Difference between method id, event id and ABI signature for event

I am confused as to what is the difference between method id, event id and abi signature. I got the abi signature of a token transfer function according to the following web3js function const ...
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2answers
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ERC20 and/or ERC721

Consider the following scenario. A person owns a asset called "A". Now the asset is very high valued and unique but you can allow other persons to own a certain part of that asset. EDIT: Ownership ...
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Can an NFT (e.g. ERC721) simultaneously belong to two different entities, say an user Owner, as well as a user Custodian?

For example, on the blockchain say you own a ERC721 Car token at your wallet address, but you want to park it in the ERC998ERC721 top down composable Garage owned by your friend, while still retaining ...
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Smart Contract overview ERC-20 instead of ERC-721

I have created ERC-721 standard but on etherscan (Ropsten) it's still showing ERC-20 standard in overview Below are my contract code, please share your thought if I'm doing something wrong. contract ...
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1answer
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all erc 721 tokens being collectibles

Considering all NFTs are unique, are all erc 721 tokens collectibles? I'm asking this because on the Etherscan website some NFTs have the collectibles tag and some do not.
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Unable to invoke smart contract function from Web3j contract wrapper

I've been learning about interacting with smart contracts through Android and the Web3j framework but have run into an issue. I'm trying to mint an ERC721 token and send it to an address but it doesn'...
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Api to get total transfer count of an ERC-721 Token

I want to retrieve the total number of an erc 721 token's transfers/ transactions. I couldn't scrape the transfers value from etherscan as well e.g. given here https://etherscan.io/token/...
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1answer
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Confusion regarding total number of ERC-721 Tokens

I have two questions: 1) I want to retrieve the list of all ERC-721 tokens. The main block explorer for Ethereum which is Etherscan shows 2,883 ERC-721 tokens on its website https://etherscan.io/...
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ERC-721 - How to avoid that an updatable tokenURI becomes a vulnerability for token trust?

I understand that one can use the tokenURI field to add the address for an endpoint that returns meta data for the given token. Let's imagine we create a unique asset with tokenId = "1" tokenURI = "...
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2answers
54 views

ERC standard: possible to set upper price limit for NFT?

Let's say I want to create a non-fungible token which represents a ticket to a venue. And I don't want ticket scalpers to buy tickets and resell these tickets for a higher price. It should only be ...
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3answers
66 views

Using a Non-Fungible token to gain access to a file

Please excuse me, I'm a layperson, not a programmer. At this time is there a way to issue NFT's to be used as a 'key' to gain access to a file on the internet? For example you create and sell an NFT ...
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109 views

How many projects are there which implement ERC1155 standard?

New ERC1155 standard which is thought to be an improved version of ERC721 and ERC20. But I see many projects still prefer ERC20 or ERC721 standards. If so, do you know any projects implementing ...
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163 views

Solidity bytecode not generated despite no errors

When does a compiler fail to generate bytecode for solidity? The code compiles entirely but both remix and solc js give proper abi but empty bytecode. The contract imports ERC721. Solidity contract: ...
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Cann't send token with looping function

Sorry, I'm a newbie on ERC721 token. Please help. I have deployed ERC721 contract in the localhost testnet. I use looping function for mint token and it works. But when I use looping function for ...
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1answer
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Can we send tokens with data input? [duplicate]

Can we send tokens with data input? I did a bit of research on erc20 but maybe this is quite complicated. Will erc 721 do this?
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107 views

Self-destructing NFT (ERC-721) token [closed]

What I want to achieve is self-destructing token. For example I'd like to have some updatable TTL value assigned to my token. If TTL is reached the token should be auto-burned. What are the best ...
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1answer
45 views

Are there any good ways to express conditional ownership on ERC20 or ERC721 tokens?

I'm currently looking for any good ways to express conditional ownership on tokens. I look into approve function of both ERC20/ERC721 but, it seems that function may be disapproved by the owner and ...
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2answers
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ERC721 - How to create many ERC721 tokens at a time

Is it possible to create many ERC721 tokens at a time? I saw this link. ERC721 - Create 1000 tokens in one function call But I don't get it. Please help me.
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149 views

gas required exceeds allowance when deploying ERC721token

I am trying to deploy Smart-contract(ERC721) on my private ethereum network. But I have this issue. Here is my genesis. { "config": { "chainId": 3333, "homesteadBlock": 1, ...
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ERC1410 Security Token

I am searching for an ERC1410 security token contract source code (must be tested) to implement in another contract, there is a github repo available but it is written in the beginning that the code ...
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1answer
227 views

Issue in ERC721 token transfer to contract address

I am using ERC721 implementation for NFT tokens. I am testing the transfer functionalities in ERC721. `transferFrom(address _from, address _to, uint256 _tokenId)` `safeTransferFrom(address ...
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2answers
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Is there a way to be notified when ERC721 is deposited?

We are coding a contract that will work with ERC721 tokens, basically a Plasma Root Chain contract. We need this contract to do some work whenever it receives a new ERC721 token from a ...
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2answers
343 views

ERC721 Token - Burn and mint again

I didn't try yet, but let's suppose the following: I have an ERC721 contract token with a total Supply of 101 My contract can mint and burn The first token has id 0 and the last one has id 100 I ...
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2answers
223 views

How to guarantee IPFS file access based on Non Fungible Token ownership (or security)?

The file is too big to be stored on the blockchain, so it is stored on IPFS. Only the person who owns a unique Non Fungible Token (or a Security Token) can access it. Of course I can encrypt the file ...
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1answer
229 views

Implementing ERC721 Marketplace

I'm working on a project where I need to implement an ERC721 marketplace. It doesn't work for some reason and wanted to know if I'm doing everything correctly. The way I approached this was: The ...
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1answer
79 views

ERC721TokenReceiver, assuming that transfer function exists?

When trying to find out if a contract implemented onERC721Received from safeTransferFrom function, are we just safely assuming the contract has all the erc721 related functionalities? such as transfer,...
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bytes data param in safeTransferFrom

In ERC721, safeTransferFrom has bytes data parameter. function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) public; how do I send data (is it in hex format?) and what ...
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1answer
35 views

What does mutability guarantees mean in erc721

Some functions from ERC-721 interface contain payable modifiers. function transferFrom(address _from, address _to, uint256 _tokenId) external payable; I was wondering why it is payable and found ...
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1answer
45 views

Is there a reason why minting is excluded in erc721 interface?

So the EIP-721 standard says, Creating of NFTs ("minting") and destruction NFTs ("burning") is not included in the specification. Your contract may implement these by other means. ...
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others accessing setApprovalForAll ERC721

While I was skimming through open zeppelin's ERC721BasicToken.sol I came across a problem. When setting the approval of a given operator function setApprovalForAll(address _to, bool _approved) ...
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ERC721Enumeration: DeclarationError for tokenOfOwnerByIndex(address owner, uint256 index)

I am new to the smart contract and please let me know why I have the error shown below. I compiled with the command, "truffle compile". I did not make any particular edits to the original contract ...