ERIC KIM ₿

Write the code

Writing a complete code for a decentralized application that integrates Ethereum and Filecoin is a large and complex task, beyond the scope of this platform. However, I can provide you with a basic outline of a Solidity smart contract that can be a starting point for your project. This example will demonstrate how to create a simple smart contract for user registration and storing references to data stored on Filecoin.

Please note that this is a simplified example and does not include Filecoin integration, which would require additional off-chain programming.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract ContentStorage {
    struct User {
        string username;
        address userAddress;
    }

    struct Content {
        string cid; // Content Identifier in Filecoin
        string description;
        address owner;
    }

    User[] public users;
    Content[] public contents;

    mapping(address => uint) public userIds;
    mapping(string => uint) public contentIds;

    // Register a new user
    function registerUser(string calldata _username) external {
        require(userIds[msg.sender] == 0, "User already registered");

        users.push(User({
            username: _username,
            userAddress: msg.sender
        }));
        userIds[msg.sender] = users.length;
    }

    // Add content reference
    function addContent(string calldata _cid, string calldata _description) external {
        require(userIds[msg.sender] != 0, "User not registered");

        contents.push(Content({
            cid: _cid,
            description: _description,
            owner: msg.sender
        }));
        contentIds[_cid] = contents.length;
    }

    // Get content details by CID
    function getContentByCID(string calldata _cid) external view returns (Content memory) {
        require(contentIds[_cid] != 0, "Content not found");
        return contents[contentIds[_cid] - 1];
    }
}

This contract includes basic functionalities:

  • User registration, where users can register themselves with a username.
  • Adding content, where users can store references to their content stored on Filecoin (represented by a CID, or Content Identifier).
  • Retrieving content details using the CID.

Remember, this is a basic example and lacks many features necessary for a full-fledged dApp, such as Filecoin integration, error handling, event logging, and security considerations like access control and preventing overwriting of existing data.

For a complete application, you would need to:

  • Develop a more robust smart contract.
  • Write backend code for Filecoin integration.
  • Create a frontend interface.
  • Thoroughly test and audit your code.

Given the complexity of blockchain development, it might be beneficial to collaborate with experienced developers, especially if you are new to Solidity or blockchain programming.

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