调查平台使用哪种设计模式以及如何使用？

Question

I'm trying to solve the best architecture for a survey system and which design patterns to use. We have the following type of questions:

• One correct answer is possible - dropdown or radio buttons
• Multiple choice - checkboxes
• Yes/No - radio buttons with Yes/No
• Short Text
• Long Text
• Number - eg When was ...?
• Correct order - eg order the answers in the correct order

I'd like to have Drawing API and Validating API So I came up with "Bridge Pattern" which is mostly used for drawing. But there's something I'm missing.

What I tried is this:

public abstract class Question : IDrawable, IValidatable
{
    protected readonly IQuestionFormatter questionFormatter;
    protected readonly IQuestionValidator validator;

    public string Title { get; set; }

    public Question(IQuestionFormatter questionFormatter, IQuestionValidator validator)
    {
        this.questionFormatter = questionFormatter;
        this.validator = validator;
    }

    public abstract void Draw();

    public abstract bool Validate();

}

    public interface IQuestionValidator
{
    bool ValidateQuestion(IEnumerable<string> userInput, 
                          IEnumerable<string> questionAnswers);
}

    public interface IQuestionFormatter
{
    string FormatQuestion(string title, IEnumerable<string> options);
}

Then I create RefinedAbstractions for MultipleChoiceQuestion, OnePossibleAnswerQuestion and ShortAnswer. The problem is that MultipleChoiceQuestion can have many correct Answers and many UserInput .

public class MultipleChoiceQuestion : Question
{
    public List<string> Options { get; set; } = new List<string>();
    public List<string> Answers { get; set; } = new List<string>();
    public List<string> UserInput { get; set; } = new List<string>();

    public MultipleChoiceQuestion(IQuestionFormatter questionFormatter, IQuestionValidator validator) : base(questionFormatter, validator)
    {
    }

    public override void Draw()
    {
        var result = questionFormatter.FormatQuestion(Title, Options);
        Console.WriteLine(result);
    }

    public override bool Validate()
    {
        return validator.ValidateQuestion(UserInput, Answers);
    }
}

OnePossibleAnswerQuestion has many Answers but One UserInput .

 public class OnePossibleAnswerQuestion : Question
{
    public string UserInput { get; set; }
    public string Answer { get; set; }
    public List<string> Options { get; set; } = new List<string>();

    public OnePossibleAnswerQuestion(IQuestionFormatter questionFormatter, IQuestionValidator validator) : base(questionFormatter, validator)
    {
    }

    public override void Draw()
    {
        var result = questionFormatter.FormatQuestion(Title, Options);
        Console.WriteLine(result);
    }

    public override bool Validate()
    {
        return validator.ValidateQuestion(new List<string> { UserInput }, new List<string> { Answer });
    }
}

ShortAnswer has one Answer and one UserInput . I'm not sure how to create the design. public class ShortAnswer : Question { public string UserInput { get; set; } public string Answer { get; set; }

    public ShortAnswer(IQuestionFormatter questionFormatter, IQuestionValidator validator) : base(questionFormatter, validator)
    {
    }

    public override void Draw()
    {
        var result = questionFormatter.FormatQuestion(Title, new List<string> { "" });
        Console.WriteLine(result);
    }

    public override bool Validate()
    {
        return validator.ValidateQuestion(new List<string> { UserInput }, new List<string> { Answer });
    }
}

But when I got to the OnePossibleAnswerQuestion or ShortAnswer the .Validate() .Draw() started smelling. Probably I have defined wrong interfaces?

My goal is to have something like this:

    List<Question> questions = new List<Question>();

    // ... add some questions using Builder or Factory Design Pattern

    // draw the questions
    foreach (var question in questions)
    {
        question.Draw();
    }

    // validate the questions
    foreach (var question in questions)
    {
        question.Validate();
    }

Could you please help me what I miss and how to composite the classes? Am I using the wrong design pattern?

Thanks in advance!

Answer 1

1) Make you validator working with Question but not with Inputs and Answers:

this.validator.Validate(this);

2) Make you formatter working with Question but not with Title and Options:

this.formatter.Format(this);

= Now you can move your Validate() and Draw() method in base class and not implement in each question type. Also you will be able to serve new question types that have new attributes, for example audio or pictures.

3) To make this useful you need to use question renderer instead of formatter. What if you decide to change input from text console to HTML page?

4) Also you might add GetInput() method for questions to have something like this:

List<Question> questions = new List<Question>();

// draw the questions
foreach (var question in questions)
{
    question.Draw();
    question.GetInput();
    question.Validate();
}

Or you can just Draw() questions and call Validate() on button click.