通过3个列表返回一个对象和一个对象
本文关键字：一个对象 返回 列表 3个 通过 | 更新日期: 2023-09-27 18:18:34
我有一个查询，它给了我一个带有类别的测验，有一个问题和一个答案，如下面的查询所示。但是，我希望只使用一个阅读器，并且希望它尽可能面向对象，这意味着我希望Quiz是根对象。所有的东西都要通过小测验。
我如何返回一个测验与类别列表，与另一个问题列表和另一个答案列表?
下面的代码:public Quiz GetQuizWithCategoriesWithQuestionsWithAnswers(int id)
{
Quiz quiz = null;
Category category = null;
Question question = null;
Answer answer = null;
dbConnection.connection.Open();
using (SqlCommand command = dbConnection.connection.CreateCommand())
{
command.CommandText = "SELECT Quiz.name, Category.name AS catName, Category.id as CatId, Category.quizId, Question.[description] as questDesc, Answer.[description] as ansDesc FROM Quiz JOIN Category ON Category.quizId = Quiz.id JOIN Question ON Question.categoryId = Category.id JOIN Answer ON Answer.questionId = Question.id WHERE Quiz.id = @id";
command.Parameters.Add("@id", SqlDbType.Int).Value = id;
var reader = command.ExecuteReader();
while (reader.Read())
{
if (quiz == null)
{
quiz = new Quiz();
quiz.name = reader.GetString(reader.GetOrdinal("name"));
quiz.id = reader.GetInt32(reader.GetOrdinal("quizId"));
}
if (category != null)
{
if (category.id != reader.GetInt32(reader.GetOrdinal("CatId")))
{
category = new Category();
category.id = reader.GetInt32(reader.GetOrdinal("CatId"));
category.name = reader.GetString(reader.GetOrdinal("catName"));
quiz.categories.Add(category);
}
}
else
{
category = new Category();
category.id = reader.GetInt32(reader.GetOrdinal("CatId"));
category.name = reader.GetString(reader.GetOrdinal("catName"));
quiz.categories.Add(category);
}
if (question != null)
{
//You'll need to get the question ID or just use the description here instead for comparison
if (question.description != reader.GetString(reader.GetOrdinal("questDesc")))
{
question = new Question();
question.description = reader.GetString(reader.GetOrdinal("questDesc"));
category.question.Add(question);
}
}
else
{
question = new Question();
question.description = reader.GetString(reader.GetOrdinal("questDesc"));
category.question.Add(question);
}
answer = new Answer();
answer.description = reader.GetString(reader.GetOrdinal("answersDesc"));
question.Answers.Add(answer);
}
}
dbConnection.connection.Close();
return quiz;
}
public class Quiz
{
[DataMember]
public int id { get; set; }
[DataMember]
public string name { get; set; }
[DataMember]
public List<Category> categories { get; set; }
[DataMember]
public List<Player> players { get; set; }
public Quiz()
{
categories = new List<Category>();
}
}
public class Category
{
[DataMember]
public int id { get; set; }
[DataMember]
public string name { get; set; }
[DataMember]
public int amount { get; set; }
[DataMember]
public List<Quiz> quiz { get; set; }
[DataMember]
public List<Question> question { get; set; }
public Category()
{
question = new List<Question>();
}
}
public class Question
{
[DataMember]
public int id { get; set; }
[DataMember]
public string description { get; set; }
[DataMember]
public Category category { get; set; }
[DataMember]
public bool isAnswered { get; set; }
[DataMember]
public List<Answer> Answers { get; set; }
public Question()
{
Answers = new List<Answer>();
}
}
public class Answer
{
[DataMember]
public int id { get; set; }
[DataMember]
public string description { get; set; }
[DataMember]
public Question question { get; set; }
[DataMember]
public bool isCorrect { get; set; }
}
我认为你的问题是你失去了值，因为你在while循环中每次都重新声明Quiz对象，所以它失去了所有它以前的值(列表)。您需要在while循环(在另一个查询和它自己的循环中)之外获取Quiz对象的基本值，并为每个列表单独查询(以避免在连接中重复)
编辑:或者只是检查测验对象是否已实例化，是否需要为类别和问题创建新对象:
using (SqlCommand command = dbConnection.connection.CreateCommand())
{
command.CommandText = "SELECT Quiz.name, QuizCategory.quizId, QuizCategory.categoryId, Category.name AS catName, Question.[description], Answer.[description] FROM Quiz JOIN QuizCategory ON QuizCategory.quizId = Quiz.id JOIN Category ON Category.id = QuizCategory.categoryId JOIN Question ON Question.categoryId = Category.id JOIN Answer ON Answer.questionId = Question.id WHERE Quiz.id = @id";
command.Parameters.Add("@id", SqlDbType.Int).Value = id;
var reader = command.ExecuteReader();
while (reader.Read())
{
if(quiz==null)
{
quiz = new Quiz();
quiz.name = reader.GetString(reader.GetOrdinal("name"));
quiz.id = reader.GetInt32(reader.GetOrdinal("quizId"));
}
if(question!=null)
{
//You'll need to get the question ID or just use the description here instead for comparison
if(question.id!=reader.GetInt32(reader.GetOrdinal("questionId"))
{
category.question.Add(question);
question = new Question();
question.description = reader.GetString(reader.GetOrdinal("description"));
}
}
else
{
question = new Question();
question.description = reader.GetString(reader.GetOrdinal("description"));
}
if(category!=null)
{
if(category.id!=reader.GetInt32(reader.GetOrdinal("categoryId"))
{
quiz.categories.Add(category);
category = new Category();
category.id = reader.GetInt32(reader.GetOrdinal("categoryId"));
category.name = reader.GetString(reader.GetOrdinal("catName"));
}
}
else
{
category = new Category();
category.id = reader.GetInt32(reader.GetOrdinal("categoryId"));
category.name = reader.GetString(reader.GetOrdinal("catName"));
}
answer = new Answer();
answer.description = reader.GetString(reader.GetOrdinal("description"));
question.Answers.Add(answer);
}
}
if(question!=null)
{
category.question.Add(question);
}
if(category!=null)
{
quiz.categories.Add(category);
}