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Building a Simple CRUD Contract with Solidity for Beginners

Sangza — Tue, 18 Apr 2023 10:44:47 +0000

If you're new to Solidity, the programming language used for writing smart contracts on the Ethereum blockchain, building a CRUD (Create, Read, Update, Delete) contract is a great way to get started. In this article, we will walk you through the process of building a basic CRUD contract using Solidity, along with some explanations of the key concepts and functions used in the code.

Introduction
Solidity is a statically-typed, contract-oriented programming language designed for developing smart contracts on the Ethereum blockchain.
CRUD operations are essential functionalities in any database-driven application. CRUD stands for:

Create: Inserting new data into the database.
Read: Retrieving data from the database.
Update: Modifying existing data in the database.
Delete: Removing data from the database.
In the context of smart contracts, CRUD operations can be implemented using Solidity functions that interact with the contract's data storage

It's a fundamental concept in blockchain development and serves as a foundation for building more complex decentralized applications (dApps).

Contract Structure
Let's take a look at the structure of our CRUD contract.

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;

contract Crud{
    struct employee{
        string name; 
        string email;
        uint256 age; 
        address walletAdress;
    }

    employee[] public Employeer;
    uint256 public TotalEmployee; 

    // Constructor
    constructor(){
        TotalEmployee = 0;
    }

    // CRUD functions go here

    // Helper functions go here
}

The contract starts with a struct definition for the employee data, which includes four fields: name, email, age, and walletAddress. This struct is used to represent the employee data that will be stored on the blockchain.

The Employeer array is used to store the employee data, and the TotalEmployee variable keeps track of the total number of employees in the array. The public keyword makes these variables accessible from outside the contract, so they can be read by other contracts or external applications.

CRUD Functions
The core functionality of our CRUD contract is implemented through four functions: create(), update(), delEmploye(), and compareStrings().

Create Function
The create() function allows you to add a new employee to the Employeer array. It takes four parameters: name, email, age, and walletAddress, which represent the employee's data. Inside the function, a new employee struct is created with the provided data, and then pushed into the Employeer array. The TotalEmployee variable is then incremented to keep track of the total number of employees.

function create (string memory name, string memory email, uint256 age, address walletAddress) public returns (uint256){
    employee memory newEmployee = employee(name, email, age, walletAddress);
    Employeer.push(newEmployee);
    TotalEmployee++;
    return TotalEmployee;
}

Update Function
The update() function allows you to update the name of an existing employee in the Employeer array. It takes two parameters: email and name, representing the email address of the employee to be updated and the new name to be set, respectively. Inside the function, a loop iterates through the Employeer array to find the employee with a matching email address. Once found, the name field of the corresponding employee struct is updated with the new name.

function update(string memory email, string memory name) external returns(bool){
    for(uint i = 0; i < TotalEmployee; i++){
        if(compareStrings(Employeer[i].email, email)){
            Employeer[i].name = name;
            return true;
        }
    }
    return false;
}

Delete Function
The delete() function allows you to delete the struct of an existing employee in the Employeer array. It takes one parameters: email , representing the email address of the employee to be deleted. Inside the function, a loop iterates through the Employeer array to find the employee with a matching email address. Once found, the name field of the corresponding employee struct is deleted.


   function delEmploye(string memory email)external returns(bool){
    assert(TotalEmployee > 0);
    for(uint i = 0 ; i < TotalEmployee; i++){
        if(compareStrings(Employeer[i].email, email)){
            Employeer[i] =  Employeer[TotalEmployee - 1];
            delete Employeer[TotalEmployee - 1];
            TotalEmployee--;
            return true;
        }

    }
    return false;
   }

Helper function
The compareStrings() function allows you to compare two strings. It takes two parameters: a and b, can be name or email. Inside the function, it returns a bool by using a hashing function that help convert the string into hash and then check if the two hash strings match.


function compareStrings(string memory a, string memory b) internal pure returns (bool) {
        return keccak256(abi.encodePacked(a)) == keccak256(abi.encodePacked(b));
    }

Conclusion:
In this article, we covered the implementation of a basic CRUD contract in Solidity. The contract allows users to create, read ,update and delete.

Consensus mechanisms

Sangza — Sun, 19 Mar 2023 15:48:26 +0000

*What are consensus mechanisms? *

Consensus mechanisms are a crucial part of blockchain technology because they guarantee the legitimacy and integrity of transactions and data recorded on the blockchain.

Some popular consensus mechanisms used in blockchain

Proof of Work (PoW): The oldest and most popular consensus technique in blockchain technology is called Proof of Work (PoW). With proof-of-work, miners compete to figure out a challenging mathematical puzzle; the first one to do so wins newly created currency. Energy is used up during this process since powerful computers are used by the miners to answer these challenges. Yet, because a successful network attack demands a lot of processing power, PoW is also regarded as being quite secure.

Proof of Stake (POS): Proof of Stake (PoS) is a newer consensus technique that tries to lower the energy consumption of PoW. With PoS, validators are selected to validate transactions based on their stake in the network, much as miners in PoW (i.e., the amount of cryptocurrency they hold). A percentage of the stake held by validators must be secured as collateral; otherwise, they risk losing their stake. Although PoS doesn't need as much computing power to validate transactions as PoW, it is thought to be more scalable and energy-efficient.

Delegated Proof of Stake (DPoS): Token owners vote for delegates in a DPoS consensus system, and these delegates validate transactions and add new blocks to the blockchain. Usually, the reputation, level of technical proficiency, and dependability of these delegates are taken into consideration. The network can be controlled by a small number of delegates in DPoS, which is faster and more energy-efficient than PoW but may also be more centralized.

Proof of Authority (PoA): In a PoA consensus method, validators are pre-selected and typically respected individuals or institutions within the community. Each block must be authorized by a particular number of validators before it can be added to the blockchain. Validators create new blocks alternately. PoA is quicker and more energy-efficient than PoW, but because validators are pre-selected, it may be less decentralized.

Proof of History (PoH): Solana, a highly effective blockchain network, invented the Proof of History (PoH) consensus mechanism. PoH is built on employing a verifiable delay function (VDF) to produce a time-ordered sequence of occurrences. The validation of transactions and the construction of a safe and expandable ledger can then be done using this sequence. PoH is intended to be more secure than PoS and more energy-efficient than PoW, removing the need for miners or validators to carry out laborious calculations.

Hybrid Consensus: To improve their scalability, security, and decentralization, some blockchains use several different consensus algorithms. To validate transactions and guarantee consensus among network participants, Ripple, for instance, combines PoW and PBFT (Practical Byzantine Fault Tolerance) consensus techniques.

How this consensus mechanism is used on different blockchain?

Proof of Work (PoW) used by bitcoin: Definition as stated above, the process of PoW in Bitcoin works as follows:

A group of pending transactions, known as a block, is created and broadcast to the network.
Using processing power, miners compete to solve a cryptographic challenge that is tied to the block. This puzzle demands the miners to locate a hash that satisfies a predetermined set of requirements; this hash is challenging to locate but simple to verify once located.
One or more Bitcoins are awarded to the miner who discovers the right hash first and publishes it to the network.
The new block is added to other nodes' copies of the blockchain after they have confirmed that it is accurate.

To keep the network's block production rate constant, the puzzle's difficulty is automatically changed. This is crucial for keeping the network secure and preventing inflation.

The Bitcoin network benefits from decentralization and security thanks to PoW. Miners have an economic incentive to act honorably and thwart attempts to alter the blockchain since they must use processing power to solve the challenge.

In general, PoW is a crucial breakthrough in the Bitcoin network since it offers a safe and decentralized means to validate transactions and uphold the network's integrity. Due to the considerable energy consumption required by the processing power needed for mining, some people are worried about how the Bitcoin network may affect the environment.

Proof of Stake(PoS) used by polygon: Definition as stated above, the process of PoS in Polygon works as follows:

When network validators "stake" their Polygon tokens as collateral, their tokens are locked up for a predetermined amount of time.
Based on the number of Polygon tokens pledged, validators are chosen at random to verify transactions and build new blocks. A validator's likelihood of selection increases with the number of tokens they have staked.
After being chosen, a validator adds a new block to the chain and verifies the transactions contained therein.
The new block is added to other nodes' copies of the blockchain after they have confirmed that it is accurate.

A validator's staked tokens may be seized as punishment if they engage in malicious behavior, such as trying to validate an invalid transaction or building an incorrect block.

PoS has various advantages to PoW, including more scalability and less energy use. PoS is more energy-efficient than PoW because it doesn't need as much computing power. Also, it is more open to a larger range of users because validators are chosen based on the quantity of cryptocurrency they own rather than their computer capacity.

Validators are in charge of approving transactions and building new blocks in Polygon's Proof of Stake (POS) implementation of PoS, while delegators can assign their tokens to validators to take part in the network's consensus process. As a result, a larger number of people can take part in safeguarding the network, resulting in a more decentralized network.

Ultimately, PoS is a crucial innovation in the Polygon network since it offers a safe and effective mechanism to confirm transactions and maintain the network's integrity.

Proof of History(PoH) used by Solana: Definition as stated above, the process of PoH in Solana works as follows:

PoH generators: A collection of PoH generators, or nodes that carry out the verifiable computations required to produce timestamps, form the basis of PoH. Every few milliseconds, each generator creates a fresh timestamp and transmits it to the network.
PoH verifiers: The PoH verifiers, which are nodes that verify the timestamps' authenticity, employ the timestamps that the PoH generators have produced. The timestamps are generated in line with the PoH protocol, and the verifiers make sure they are in the right order.
Transaction processing: A timestamp from the PoH sequence is included in every new transaction that is sent to the Solana network. This timestamp is needed to confirm the transaction's order and guarantee that it is included in the correct block.
Consensus: To ensure that all nodes on the network concur on the state of the blockchain, PoH is utilized in conjunction with a conventional consensus mechanism called Tower BFT.

The Solana blockchain is able to attain great levels of speed, efficiency, scalability, and security thanks to PoH, a novel consensus method. Solana is well-suited for a variety of use cases because it can swiftly and simultaneously handle a high number of transactions thanks to PoH.

In conclusion, consensus mechanisms are a key component of blockchain technology, and the choice of one depends on a number of variables, including the goal of the network, the need for scalability, the need for security, and the trade-off between centralization and decentralization.

A Brief Knowledge of Flutter

Sangza — Sun, 19 Mar 2023 13:50:44 +0000

What is Flutter?
Google developed the open-source Flutter framework for building mobile apps. With only one codebase, it enables developers to create fast, cross-platform mobile apps for iOS, Android, and the web. Flutter builds UI components using a reactive programming model and a widget-based architecture, enabling quick development cycles, adaptable and lovely user interfaces, and fluid animations.

What is flutter used for?

Flutter has come to solve front-end developers' problems. With Flutter, you don’t need to worry about learning Android, iOS, and web development separately. With a single codebase, your app can run on them both.

Creation of Mobile Apps: Flutter is frequently used to create mobile apps with a single codebase for both Android and iOS devices. With the use of Flutter, developers can quickly produce stunning, high-performing mobile applications.

Creation of Web Apps: Flutter enables programmers to create Web Apps using the same codebase as their Mobile Apps ensuring a smooth experience on all Platforms.

Developing apps for Windows, macOS, and Linux is also supported by Flutter.

Developing Cross-Platform applications: Using Flutter, you can create cross-platform apps that enable developers to create a single code base that can be used across a variety of platforms, cutting down on development costs and time.

Best way to create an MVP: Because of its quick development cycle and user-friendliness, Flutter is a great candidate for creating Minimum Viable Products (MVPs).

What programming language does flutter use?

The Dart programming language is used to create Flutter apps, which take advantage of many of its more sophisticated features.

Flutter runs in the Dart VM, which has a just-in-time execution engine while developing and debugging an application. This permits quick compilation times and "hot reloading," which lets changes to source files be injected into an application that is already executing. Flutter takes this a step further by supporting stateful hot reloading, in which most source code changes are instantaneously reflected in the running app without the need for a restart or any state loss.

Release versions of Flutter apps use ahead-of-time (AOT) compilation for greater performance, except for the Web, where code is translated to JavaScript.

Dart's Pub package management and software repository, enables users to publish and use customized packages and plugins particular to Flutter.

How to install Flutter

Flutter has good and easy-to-read documentation that would show you step-by-step how to get it running on your system. https://docs.flutter.dev/get-started/install.I would not go deep into how you can install Flutter; you can read my next article on how to do this.

Common Questions Asked

Is flutter for the front end or the back end?

Answer: Flutter is primarily a front-end framework for building mobile and web applications. For iOS, Android, web, and desktop platforms, it offers a rich collection of pre-built UI widgets, tools, and libraries that enable developers to produce stunning, responsive, and effective apps.

Flutter does, however, have certain capabilities for interacting with backend services. It has built-in classes like http and dio that it can use to manage responses when making http queries to RESTful APIs. Flutter also enables WebSocket protocols for communication with backend services.

Having said that, Flutter is not a full-fledged backend framework, even if it does offer some capabilities for interacting with backend services. Developers generally use other technologies like Node.js, and Django to build more complicated backend systems.

Is Flutter open source?
Answer: Flutter is an open-source project that enables you to use it for nothing while also making changes to the program.

Pros and Cons of flutter

Pros

Flutter is quick since it doesn't require a JavaScript bridge because it uses the Dart programming language that has been turned into native code. Apps made as a result are quick and responsive.

Flutter is used to create cross-platform applications. it is possible to create apps for both iOS and Android smartphones using the same code from a single codebase.

Flutter is free and open source

As a Google product, it benefits greatly from the company's enormous support and ongoing improvement efforts.

It provides easy debugging and Automated testing.

Applications made using Flutter can be created with many aspect ratios and screen sizes. Because of this, making apps that look beautiful on both phones and tablets is simple.

Cons

Despite having a wide variety of widgets, Flutter still lacks third-party libraries. When utilizing Flutter, one must keep in mind that flutter lacks libraries necessary for adding features and functionality to apps.

Compared to more established languages like Java, Dart is a young language. This suggests that there might be a small pool of developers who are knowledgeable about and good at using it.

Flutter apps are typically bigger than those created using other frameworks because they come with built-in widgets.

In conclusion,
If you’re looking to make a career in app development, Flutter is the go-to language, and its space is still young and growing.
Start by going through the documentation, buying an Udemy course, or scrabble through Youtube.