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// SPDX-License-Identifier: MIT
pragma solidity >=0.4.22 <0.9.0;
contract Persssist {
string public name = "Persssist";
uint256 public fileCount = 0;
// this mapping behaves as a "catalog"
// of files uploaded to the storage, we declare
// it as public in order to access it directly from the Frontend
mapping(uint256 => File) public files;
struct File {
uint256 fileId;
string filePath;
uint256 fileSize;
string fileType;
string fileName;
address payable uploader;
event FileUploaded(
uint256 fileId,
string filePath,
uint256 fileSize,
string fileType,
string fileName,
address payable uploader
// we upload the file metadata
// to the smart contract files
// mapping in order to persist
// the information.
function uploadFile(
string memory _filePath,
uint256 _fileSize,
string memory _fileType,
string memory _fileName
) public {
require(bytes(_filePath).length > 0);
require(bytes(_fileType).length > 0);
require(bytes(_fileName).length > 0);
require(msg.sender != address(0));
require(_fileSize > 0);
// since solidity mappings
// do not have a lenght attribute
// the simplest way to control the amount
// of files is using a counter
files[fileCount] = File(
// From the frontend application
// we can listen the events emitted from
// the smart contract in order to update the UI.
emit FileUploaded(
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