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Build a Decentralized News Feed using Reactjs, TailwindCSS, Etherjs, IPFS & Solidity
//SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.0;
import "hardhat/console.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
contract NewsFeed {
uint256 totalFeeds;
using Counters for Counters.Counter;
Counters.Counter private _feedIds;
constructor() {
console.log("NewsFeed deployed");
}
/*
* I created a struct here named Feed.
* A struct is a custom datatype where we can customize what we want to hold inside it.
*/
struct Feed {
uint256 id;
string title;
string description;
string location;
string category;
string coverImageHash;
string date;
address author;
}
/*
* A little magic is known as an event in Solidity!
*/
event FeedCreated(
uint256 id,
string title,
string description,
string location,
string category,
string coverImageHash,
string date,
address author
);
/*
* I declare variable feeds that let me store an array of structs.
* This is what holds all the feeds anyone ever created.
*/
Feed[] feeds;
/*
* This function will be used to get all the feeds.
*/
function getAllFeeds() public view returns (Feed[] memory) {
/*
* This is a function that will return the length of the array.
* This is how we know how many feeds are in the array.
*/
return feeds;
}
/*
* This function will be used to get the number of feeds.
*/
function getTotalFeeds() public view returns (uint256) {
return totalFeeds;
}
/*
* This is a function that will be used to get a feed.
* It will take in the following parameters:
* - _id: The id of the feed
*/
function getFeed(uint256 _id) public view returns (Feed memory) {
/*
* We are using the mapping function to get the feed from the mapping.
* We are using the _id variable to get the feed from the mapping.
*/
return feeds[_id];
}
/*
* This function will be used to create a news feed.
* It will take in the following parameters:
* - _title: The title of the feed
* - _description: The description of the feed
* - _location: The location of the feed
* - _category: The category of the feed
* - _coverImageHash: The hash of the cover image of the feed
* - _date: The date of the feed
*/
function createFeed(
string memory _title,
string memory _description,
string memory _location,
string memory _category,
string memory _coverImageHash,
string memory _date
) public {
// Validation
require(bytes(_coverImageHash).length > 0);
require(bytes(_title).length > 0);
require(bytes(_description).length > 0);
require(bytes(_location).length > 0);
require(bytes(_category).length > 0);
require(msg.sender != address(0));
totalFeeds++;
/* Increment the counter */
_feedIds.increment();
/*
* We are using the struct Feed to create a news feed.
To create a news feed* We use the id, title, description, location, category, coverImageHash, date, and author variables.
*/
feeds.push(
Feed(
_feedIds.current(),
_title,
_description,
_location,
_category,
_coverImageHash,
_date,
msg.sender
)
);
/*
* We are using the event FeedCreated to emit an event.
To emit an event*, We use the id, title, description, location, category, coverImageHash, date, and author variables.
*/
emit FeedCreated(
_feedIds.current(),
_title,
_description,
_location,
_category,
_coverImageHash,
_date,
msg.sender
);
}
}
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