Tips for creating a simulated comment section

To complete this task, you will be constructing a simulated comments section. Focus

Our attention will be on two key elements:

Users

There are three types of users in this scenario - regular users, moderators, and admins. Regular users can only add new comments and edit their own. Moderators have the ability to delete comments (to get rid of trolls), while admins can edit or delete any comment. Users can log in and out, with their last login time being tracked.

Comments

Comments consist of a message, a timestamp, and the author. Comments can also be replies, so we will keep track of the parent comment.

Below is my code:

class Admin extends Moderator {
  constructor(name) {
    super(name);
  }
  canEdit(comment) {
    return true;
  }
}

class Comment {
  constructor(author, message, repliedTo) {
    this.createdAt = new Date();
    this._author = author;
    this._message = message;
    this.repliedTo = repliedTo || null;
  }
  getMessage() {
    return this._message;
  }
  setMessage(message) {
    this._message = message;
  }
  getCreatedAt() {
    return this.createdAt;
  }
  getAuthor() {
    return this._author;
  }
  getRepliedTo() {
    return this.repliedTo;
  }
  getString(comment) {
    const authorName = comment.getAuthor().getName();
    if (!comment.getRepliedTo()) return authorName;
    return `${comment.getMessage()} by ${authorName} (replied to ${this.getString(comment.getRepliedTo())})`;
  }
  toString() {
    const authorName = this.getAuthor().getName();
    if (!this.getRepliedTo()) {
      return `${this._message} by ${authorName}`;
    }
    return this.getString(this);
  }
}

I encountered an issue

The toString method should display the accurate hierarchy (including nested replies)

javascript

Answer №1

While this task was presented as an assignment, the question posed some technical and unclear challenges; however, here is the solution that has been tried and tested.

class User {
  constructor(name) {
   this._name = name;
   this._loggedIn = false;
   this._lastLoggedInAt = null;
  }
  isLoggedIn() {
    return this._loggedIn;
  }
  getLastLoggedInAt() {
    return this._lastLoggedInAt;
  }
  logIn() {
    this._lastLoggedInAt = new Date();
    this._loggedIn = true;
  }
  logOut() {
    this._loggedIn = false
  }
  getName() {
    return this._name;
  }
  setName(name) {
    this._name = name;
  }
  canEdit(comment) {
    if(comment._author._name === this._name) {
      return true;
    }
    return false;
  }
  canDelete(comment) {
    return false;
  }
}

class Moderator extends User {
   constructor(name) {
     super(name);
   }
   canDelete(comment) {
     return true;
   }
}

class Admin extends Moderator {
  constructor(name) {
    super(name)
  }
  canEdit(comment) {
    return true;
  }
}

class Comment {
   constructor(author = null, message, repliedTo = null) {
     this._createdAt = new Date();
     this._message = message;
     this._repliedTo = repliedTo;
     this._author = author;
   }
   getMessage() {
     return this._message;
   }
   setMessage(message) {
     this._message = message;
   }
   getCreatedAt() {
     return this._createdAt;
   }
   getAuthor() {
     return this._author;
   }
   getRepliedTo() {
     return this._repliedTo;
   }
   toString() {
     if(this._repliedTo === null) {
        return this._message + " by " + this._author._name
     }
     return this._message + " by " + this._author._name + " (replied to " + 
          this._repliedTo._author._name + ")"
   }
 }

The mistake occurred because a getName() method was being called on the getAuthor method, which was not available. To retrieve the author's name directly from the Comment, you can use this._author._name.

Answer №2

Utilizing the JavaScript constructor coding style, I crafted this solution without requiring a change in your current coding style. Notice that the fields (_author, _message, _repliedTo) are kept private, restricting access to them through public methods only. This approach is evident in the toString() method implementation.

function Comment(author, message, repliedTo = null) {
  var _author = author;
  var _message = message;
  var _repliedTo = repliedTo;
  
  this.getAuthor = function() {
    return _author;
  };
  
  this.getRepliedTo = function() {
    return _repliedTo;
  };
  
  this.toString = function() {
    return ((_repliedTo === null) ? message + " by " + _author.getName() : message + " by " + _author.getName() + " (replied to " + this.getRepliedTo().getAuthor().getName() + ")");
  }
};

Answer №3

If you want to eliminate the getString() method...

changeToStringMethod() 
{
    return ((this._repliedTo === null) ? this._message + " by " + 
           this._author.getName() : this._message + " by " + 
           this._author.getName() + " (replied to " + this._repliedTo._author.getName() + ")");
}

Answer №4

class User {
  function __construct($username) {
   private $username;
   private $loggedInStatus;
   private $lastLoginTime;

   $this->username = $username;
   $this->loggedInStatus = false;
   $this->lastLoginTime = null;
  }
  function checkIfLoggedIn() {
    return $this->loggedInStatus;
  }
  function getLastLoginTime() {
    return $this->lastLoginTime;
  }
  function logInUser() {
    $this->lastLoginTime = new Date('Y-m-d H:i:s');
    $this->loggedInStatus = true;
  }
  function logOutUser() {
    $this->loggedInStatus = false;
  }
  function getUsername() {
    return $this->username;
  }
  function setUserame($username) {
    $this->username = $username;
  }
  function canModifyComment($comment) {
    if($comment->author->username === $this->username) {
      return true;
    }
    return false;
  }
  ...
}

class Moderator extends User {
   function __construct($username) {
     $this->username = $username;
   }
   function allowCommentDeletion($comment) {
     return true;
   }
}

class Admin extends Moderator {
  function constructor($username) {
    $this->username = $username;
  }
  function canModifyComment($comment) {
    return true;
  }
}

class Comment {
   function __construct($writer = null, $content, $replyTo = null) {

    private $createdAt;
    private $content;
    private $replyTo;
    private $writer;

     $this->createdAt = new Date('Y-m-d H:i:s');
     $this->content = $content;
     $this->replyTo = $replyTo;
     $this->writer = $writer;
   }
   ...
}

Answer №5

For those in need of the Java version:


import java.util.Date;

public class Solution {
  public static class User {
    String name;
    boolean loggedIn;
    Date lastLoggedInAt;
    
    public User(String name) {
      this.name = name;
      this.loggedIn = loggedIn;
      this.lastLoggedInAt = lastLoggedInAt;
    }
    
    public boolean isLoggedIn() {
      return this.loggedIn;
    }
    
    public Date getLastLoggedInAt() {
      return this.lastLoggedInAt;
    }
    
    public void logIn() {
      this.lastLoggedInAt = new Date();
      this.loggedIn = true;
    }
    
    public void logOut() {
      this.loggedIn = false;
    }
    
    public String getName() {
      return this.name;
    }
    public void setName(String name) {
      this.name = name;
    }
    
    public boolean canEdit(Comment comment) {
      if(comment.getAuthor().name == this.name) {
      return true;
    }
      return false;
    }
    
    public boolean canDelete(Comment comment) {
      return false;
    }
  }

  public static class Moderator extends User{
    public Moderator(String name) {
      super(name);
    }
    
    public boolean canDelete(Comment comment) {
     return true;
   }
  }

  public static class Admin extends Moderator{
    public Admin(String name) {
       super(name);
    }
    
     public boolean canEdit(Comment comment) {
     return true;
   }
  }
  
  public static class Comment {
    User author;
    //Make sure to also reference author below
    String message;
    Comment comment;
    Date createdAt;
    Comment repliedTo;
    
    public Comment(User author, String message) {
      this.author = author;
      this.message = message;
    }
    
    public Comment(User author, String message, Comment repliedTo) {
      this.author = author;
      this.message = message;
      this.repliedTo = repliedTo;
    }
    
    public String getMessage() {
      return this.message;
    }
    
    public void setMessage(String message) {
      this.message = message;
    }
    
    public Date getCreatedAt() {
      return this.createdAt;
    }
    
    public User getAuthor() {
      return this.author;
    }
    
    public Comment getRepliedTo() {
      return this.repliedTo;
    }
    
    public String toString() {
      if(this.repliedTo == null) {
        return this.message + " by " + this.author.getName();
     }
     return this.message + " by " + this.author.getName() + " (replied to " + 
          this.repliedTo.getAuthor().name + ")";
   }
    }
  }

Answer №6

The solutions previously mentioned may not meet the necessary criteria for passing unit tests in this particular assignment. Below is an alternative approach that I have used successfully to fulfill the requirements:

export class User {
  constructor(name) {
    this._name = name;
    this._lastLoginDate = null;
    this._loggedIn = false;
  }

  isLoggedIn() {
    return this._loggedIn;
  }

  getLastLoggedInAt() {
    return this._lastLoginDate;
  }

  logIn() {
    this._lastLoginDate = new Date();
    return Promise.resolve('Success').then(() => {
      this._loggedIn = true;
    });
  }

  logOut() {
    this._loggedIn = false;
  }

  getName() {
    return this._name;
  }

  setName(name) {
    this._name = name;
  }

  canEdit(comment) {
    if (comment.getAuthor().getName() === this.getName()) {
      return true;
    }
    return false;
  }

  canDelete(comment) {
    return false;
  }
}

export class Moderator extends User {
  constructor(name) {
    super(name);
  }

  canDelete(comment) {
    return true;
  }
}

export class Admin extends Moderator {
  constructor(name) {
    super(name);
  }

  canEdit(comment) {
    return true;
  }
}

export class Comment {
  constructor(author, message, repliedTo = null) {
    this._author = author;
    this._message = message;
    this._repliedTo = repliedTo || null;
    this._createdAt = new Date();
  }

  getMessage() {
    return this._message;
  }

  setMessage(message) {
    this._message = message;
  }

  getCreatedAt() {
    return this._createdAt;
  }

  getAuthor() {
    return this._author;
  }

  getRepliedTo() {
    return this._repliedTo;
  }

  toString() {
    return this.getRepliedTo() === null
      ? `${this.getMessage()} by ${this.getAuthor().getName()}`
      : `${this.getMessage()} by ${this.getAuthor().getName()} (replied to ${this.getRepliedTo()
          .getAuthor()
          .getName()})`;
  }
}

Answer №7

To implement this solution in TypeScript:

export class User {
  private _name: string;
  private _loggedIn: boolean;
  private _lastLoggedInAt: Date | null;
  constructor(name: string) {
    this._name = name;
    this._loggedIn = false;
    this._lastLoggedInAt = null;
  }

  isLoggedIn(): boolean {
    return this._loggedIn;
  }

  getLastLoggedInAt(): Date | null {
    return this._lastLoggedInAt;
  }

  async logIn(): Promise<void> {
    this._lastLoggedInAt = new Date();
    await Promise.resolve("suceess");
    this._loggedIn = true;
  }

  logOut(): void {
    this._loggedIn = false;
  }

  getName(): string {
    return this._name;
  }

  setName(name: string): void {
    this._name = name;
  }

  canEdit(comment: Comment): boolean {
    if (comment.getAuthor().getName() === this._name) {
      return true;
    }
    return false;
  }

  canDelete(comment: Comment): boolean {
    return false;
  }
}

export class Moderator extends User {
  constructor(name: string) {
    super(name);
  }
  canDelete(_comment: Comment): boolean {
    return true;
  }
}

export class Admin extends Moderator {
  constructor(name: string) {
    super(name);
  }
  canEdit(_comment: Comment): boolean {
    return true;
  }
}

export class Comment {
  private _author: User;
  private _message: string;
  private _repliedTo?: Comment | null;
  private _createdAt: Date;
  constructor(author: User, message: string, repliedTo?: Comment) {
    this._author = author;
    this._message = message;
    this._repliedTo = repliedTo;
    this._createdAt = new Date();
  }

  getMessage(): string {
    return this._message;
  }

  setMessage(message: string): void {
    this._message = message;
  }

  getCreatedAt(): Date {
    return this._createdAt;
  }

  getAuthor(): User {
    return this._author;
  }

  getRepliedTo(): Comment | null {
    if (this._repliedTo) {
      return this._repliedTo;
    }
    return null;
  }

  toString(): string {
    if (this.getRepliedTo()) {
      return `${this.getMessage()} by ${this.getAuthor().getName()} (replied to ${this._repliedTo
        ?.getAuthor()
        .getName()})`;
    }
    return `${this.getMessage()} by ${this.getAuthor().getName()}`;
  }
}

Add some Jest unit tests for validation:

describe('Normal user tests', function() {
  it('should retrieve the user\'s name', () => {
    const user = new User("User 1");
    expect(user.getName()).toEqual('User 1');
  });

  // Add more test cases for the Normal user here...
});

describe('Moderator user tests', function() {
  it('should allow deletion of comments as a moderator', () => {
    const moderator = new Moderator("Moderator 1");
    const message = "Hello there"
    const comment = new Comment(moderator, message);
    expect(moderator.canDelete(comment)).toBeTruthy();
  });

  // Additional test scenarios for the Moderator user go here...
});

describe('Admin user tests', function() {
  it('should have editing privileges for comments as an admin', () => {
    const admin = new Admin("Admin 1");
    const message = "Hello there"
    const comment = new Comment(admin, message);
    expect(admin.canEdit(comment)).toBeTruthy();
  });

  // Include more test cases for the Admin user...
});

describe('Comment tests', function() {
  // Write test cases for the Comment class methods...
});

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