Question

我有两个主要的域类。每个域类代表一个表。这两个域类具有MANY-TO-MANY关系。所以我创建了另一个域类，为两个域类创建了一对一的关系。域类是：

public class Child
    {
        public Child()
        {
            this.UserLog = new UserLog();
            this.ChildCares = new List<ChildCare>();
        }

        public Guid ChildId { get; set; }
        public string Surname { get; set; }
        public string FirstName { get; set; }
        public string MiddleName { get; set; }
        public DateTime DateOfBirth { get; set; }
        public string BirthCountry { get; set; }
        public string CitizenCountry { get; set; }
        public string FatherSurname { get; set; }
        public string FatherFirstName { get; set; }
        public string FatherMiddleName { get; set; }
        public string MotherSurname { get; set; }
        public string MotherFirstName { get; set; }
        public string MotherMiddleName { get; set; }
        public string Street { get; set; }
        public string City { get; set; }
        public string State { get; set; }
        public string PostalCode { get; set; }
        public string Country { get; set; }
        public string Telephone { get; set; }
        public string Mobile { get; set; }
        public virtual UserLog UserLog { get; private set; }
        public virtual ICollection<ChildCare> ChildCares { get; private set; }

public class Institute
    {
        public Institute()
        {
            this.UserLog = new UserLog();
            this.ChildCares = new List<ChildCare>();
        }

        public Guid InstituteId { get; set; }
        public string InstituteName { get; set; }
        public int Capacity { get; set; }
        public decimal AmountPerDay { get; set; }
        public string Street { get; set; }
        public string City { get; set; }
        public string State { get; set; }
        public string PostalCode { get; set; }
        public string Country { get; set; }
        public string Telephone { get; set; }
        public string Mobile { get; set; }
        public UserLog UserLog { get; set; }
        public virtual ICollection<ChildCare> ChildCares { get; private set; }
    }

public class ChildCare
    {
        public ChildCare()
        {
            this.UserLog = new UserLog();
            //this.Children = new Child();
            //this.Institute = new Institute();
        }
        public Guid ChildCareId { get; set; }
        public Guid ChildId { get; set; }
        public Guid InstituteId { get; set; }
        public DateTime StartDate { get; set; }
        public DateTime EndDate { get; set; }
        public UserLog UserLog { get; set; }
        public virtual Child Children { get; set; }
        public virtual Institute Institute { get; set; }

Child表有三行。 Institute表有SIX行。 ChildCare表有三行。不，我想通过加入Child，Institute，ChildCare来选择数据。由于ChildCare类同时具有Child和Institute对象。所以我想从ChildCare类查询。我希望Linq查询将数据作为以下对象的集合返回，这是另一个域类。

public class ChildDayCare
    {
        public string ChildrenName { get; set; }
        public string InstituteName { get; set; }
        public DateTime StartDate { get; set; }
        public DateTime EndDate { get; set; }
        public decimal ChargePerDay { get; set; }
    }

现在我写的查询如下：

public IList<ChildCare> GetAllChildrenCareAsList()
        {
            try
            {
                var childCareList = base.GetAll();
                var childCareArr = childCareList as ChildCare[] ?? childCareList.ToArray();
                return childCareArr.Any() ? childCareArr.ToList() : null;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

var childCares = GetAllChildrenCareAsList();

            if (childCares != null)
            {

                IList<Child> children = childCares.Select(t => t.Children).ToList();
                IList<Institute> institutes = childCares.Select(t => t.Institute).ToList();

                var childDacareList = (from cc in childCares
                                       join cd in children on cc.Children.ChildId equals cd.ChildId
                                       join ins in institutes on cc.Institute.InstituteId equals ins.InstituteId
                                       select new ChildDayCare
                                       {
                                           ChildrenName = cd.MiddleName, //cd.FirstName + " " + cd.MiddleName + " " + cd.Surname,
                                           InstituteName = ins.InstituteName,
                                           StartDate = cc.StartDate,
                                           EndDate = cc.EndDate,
                                           ChargePerDay = ins.AmountPerDay
                                       }).ToList();

                return childDacareList;
            }

查询应显示三行。但相反它显示9行。谁能告诉我我做错了什么。

Answer 1

以下代码将有所帮助： IList institutes = children.Select（t =＆gt; t.Institute）。ToList（）;

使用LINQ在多个表之间进行连接并未显示准确的结果

1 个答案: