Develop Reference

How to effectively implement 1 to many relationship?

I have an EF model to is connected 1 to 1 for many tables but I am having trouble connecting a 1 to many table. Currently using EF6 on .Net 4.8. The error I am recieving is "Multiplicity is not valid in Role '' in relationship 'Login_Users'. Because the Dependent Role refers to the key properties, the upper bound of the multiplicity of the Dependent Role must be '1'"
The main table is
Users
public partial class Users
{
public Users()
{
this.Login = new HashSet<Login>();
this.Phone = new HashSet<Phone>();
}
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
public string Email { get; set; }
public System.DateTime BirthDate { get; set; }
public int LastFourSSN { get; set; }
public Nullable<int> AddressId { get; set; }
public virtual Address Address { get; set; }
public virtual ICollection<Login> Login { get; set; }
public virtual ICollection<Phone> Phone { get; set; }
}
One to one tables
public partial class Login
{
public Login()
{
this.Login_Track = new HashSet<Login_Track>();
this.Policy = new HashSet<Policy>();
}
public string Username { get; set; }
public string Password { get; set; }
[Key, ForeignKey("Users")]
public Nullable<int> UserId { get; set; }
public System.DateTime CreationDate { get; set; }
public Nullable<System.DateTime> LastLoginDate { get; set; }
public virtual Users Users { get; set; }
}
Address
public partial class Address
{
public Address()
{
this.Users = new HashSet<Users>();
}
[Key, ForeignKey("Users")]
public int Id { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string City { get; set; }
public string County { get; set; }
public string State { get; set; }
public string PostalCode { get; set; }
public virtual ICollection<Users> Users { get; set; }
}
1 to many table
public partial class Phone
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Number { get; set; }
public string Type { get; set; }
[ForeignKey("Users")]
public Nullable<int> UserId { get; set; }
public virtual Users Users { get; set; }
}

Table Per Type(TPT) hierarchy vs Navigation in Entity Framework

I have been reading about Entity Framework during the pass few weeks. I came across TPT subject. I am a little bit confused and have difficulty to differentiate between TPT and Navigation. When should we choose one over another. Please take a look at the code below.
A. Navication
public class Employee
{
public int EmployeeId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Gender { get; set; }
public List<ContractEmployee> ContractEmployees { get; set; }
public List<PermanentEmployee> PermanentEmployees { get; set; }
}
public class ContractEmployee
{
public int HourlyWorked { get; set; }
public int HourlyPay { get; set; }
public Employee Employee { get; set; }
}
public class PermanentEmployee
{
public int AnnualSalary { get; set; }
public Employee Employee { get; set; }
}
B. TPT
[Table("Employee")]
public class Employee
{
public int EmployeeId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Gender { get; set; }
}
[Table("ContractEmployee")]
public class ContractEmployee : Employee
{
public int HourlyWorked { get; set; }
public int HourlyPay { get; set; }
}
[Table("ContractEmployee")]
public class PermanentEmployee : Employee
{
public int AnnualSalary { get; set; }
}

Mapping 4 tables in Entity Framework using Fluent API

I am having difficulties in creating custom mapping table in EF6.
I have 4 tables:
Student
Instructor
Questions
Course
What I want is to create a table that will include all primary keys of those 4 tables and add a score column to it.
What is the command that should I use in Entity Framework Fluent API?
This is the classes that i have created
public class Student
{
public Student()
{
this.Courses = new HashSet<Course>();
}
public int StudentId { get; set; }
public string LastName { get; set; }
public string FirstMidName { get; set; }
public virtual ICollection<Course> Courses { get; set; }
}
public class Instructor
{
public Instructor()
{
this.Courses = new HashSet<Course>();
}
public int InstructorId { get; set; }
public string LastName { get; set; }
public string FirstMidName { get; set; }
public virtual ICollection<Course> Courses { get; set; }
}
public class Course
{
public Course()
{
this.Instructors = new HashSet<Instructor>();
this.Students = new HashSet<Student>();
}
public int CourseId { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public virtual ICollection<Instructor> Instructors { get; set; }
public virtual ICollection<Student> Students { get; set; }
}
public class Question
{
public int QuestionId { get; set; }
public string Description { get; set; }
public int CategoryId { get; set; }
public Category Category { get; set; }
}

select multiple column from include table in LINQ

My question is about how can i select some one-two column from those tables are included and at the end when i am selecting as list it is returning list of parent object but child are contain those column i mention to select?
var testq = _db.Homes
.Include(x => x.Indexs.Cities.Proviences.Regions)
.Include(x => x.Images)
.Select(x => new Homes {
Images = x.Images,
Address = x.Address,
Indexs.Cities.Proviences.Regions =
x.Indexs.Cities.Proviences.Regions.Name });
At the end I need to have list of home model (List) and just images and Address and region name have value and important just those are selected from database not all infromation in the tables. I am trying to make a query with better performance
Edit Add Models
public partial class dbContext : DbContext
{
public virtual DbSet<City> Cities { get; set; }
public virtual DbSet<Province> Provinces { get; set; }
public virtual DbSet<Region> Regions { get; set; }
public virtual DbSet<Index> Indexs { get; set; }
public virtual DbSet<Home> Homes { get; set; }
public virtual DbSet<Images> Imageses { get; set; }
}
public partial class Home
{
public Home()
{
Imageses = new HashSet<Images>();
}
[Key]
public int IDHome { get; set; }
[Required]
[StringLength(5)]
public string Cap { get; set; }
[Required]
[StringLength(10)]
public string Number { get; set; }
[Required]
[StringLength(50)]
public string Address { get; set; }
....
public virtual Index Indexs { get; set; }
public virtual ICollection<Images> Imageses { get; set; }
}
public class Index
{
public int ID { get; set; }
public int IDHome { get; set; }
....
public virtual City Cities { get; set; }
}
public partial class City
{
[Key]
public int ID { get; set; }
public int IDProvincia { get; set; }
public decimal Latitudine { get; set; }
public decimal Longitudine { get; set; }
[Required]
[StringLength(100)]
public string Name { get; set; }
....
public virtual Province Provinces { get; set; }
}
public partial class Province
{
[Key]
public int ID { get; set; }
public int IDRegione { get; set; }
[Required]
[StringLength(50)]
public string Name { get; set; }
[Required]
[StringLength(3)]
public string Init { get; set; }
...
public virtual Region Regions { get; set; }
}
public partial class Region
{
[Key]
public int ID { get; set; }
[Required]
[StringLength(50)]
public string Name { get; set; }
public DateTime DataInsert { get; set; }
...
}
public class Images
{
public int ID { get; set; }
public string Path { get; set; }
...
}
absolutely tables have more column just add here as example

you have to define a new type with the fields you need, or use an anonymous type.
.Select(x => new {
Images = x.Images,
Address = x.Address,
Indexs.Cities.Proviences.Regions =
x.Indexs.Cities.Proviences.Regions.Name });

Entity Framework 6 asp.net Code First Setup

Hi guys I am spinning wheels on this one. I am using EF6 and ASP.Net 4.6. I have a given table which has student information and parent information. A student can have many parents and a parent can have many students. Call this table 'Contact'. I am to create a table called 'Request' which will hold information for a parent submitting a request for his student. I will create a lookup table with two columns, one for student id and one for parent id called 'StudentParents'. I want to be able to have the parent log in, select his student from a drop down of all of his students and submit the request. The many to many relationship is throwing me off as far as my include statements. How can I get EF to set up this structure so that when I GetRequest(id) I can get the Student info and the Parent info to be included? Here is my code that wont Include anything other than the request.
public class Contact
{
[Key]
public int id { get; set; }
public string student_id { get; set; }//This is the Student ID
public string last_name { get; set; }
public string first_name { get; set; }
public string middle_initial { get; set; }
public string grade { get; set; }
public int current_school_id { get; set; }
public string current_school_name { get; set; }
[Display(Name = "Parent Last Name")]
public string contact_first_name { get; set; }
[Display(Name = "Parent Middle Name")]
public string contact_middle_name { get; set; }
[Display(Name = "Parent Last Name")]
public string contact_last_name { get; set; }
public string contact_relationship { get; set; }
[Display(Name = "Parent Email")]
public string contact_email { get; set; }
[Display(Name = "Parent Address")]
public string login { get; set; }//This is the Parent ID
public string Classif_description { get; set; }
}
public class Request
{
[Key]
public int id { get; set; }
public Student student_id { get; set; }
public Contact login { get; set; }
[Display(Name = "First School Choice")]
public string firstSchool { get; set; }
[Display(Name = "Second School Choice")]
public string secSchool { get; set; }
[Display(Name = "Rising Grade")]
public string rising_grade { get; set; }
public DateTime ReqSubmitted { get; set; }
public string ReqStatus { get; set; }
public DateTime Created { get; set; }
public DateTime Modified { get; set; }
public string ModifBy { get; set; }
}
public class Parent
{
public int id { get; set; }
public string contact_first_name { get; set; }
public string contact_middle_name { get; set; }
public string contact_last_name { get; set; }
public string contact_relationship { get; set; }
public string contact_email { get; set; }
public string contact_address { get; set; }
public string contact_city { get; set; }
public string contact_zip { get; set; }
[Key]
public string login { get; set; }
public string contact_pw { get; set; }
public string phone { get; set; }
public string phone_type { get; set; }
public Parent() { }
public virtual ICollection<Student> Students { get; set; }
}
public class Student
{
[Key]
public int id { get; set; }
public int student_id { get; set; }
public string last_name { get; set; }
public string first_name { get; set; }
public string middle_initial { get; set; }
public DateTime birthdate { get; set; }
public string gender { get; set; }
public string grade { get; set; }
public string Fed_race_description { get; set; }
public string Classif_description { get; set; }
public int current_school_id { get; set; }
public string current_school_name { get; set; }
public int home_school_id { get; set; }
public string home_school_name { get; set; }
public Student()
{
this.Parents = new HashSet<Parent>();
}
public virtual ICollection<Parent> Parents { get; set; }
}
public class OEContext : DbContext
{
public OEContext() : base("name=OEContext")
{
}
public DbSet<Request> Requests { get; set; }
public DbSet<Parent> Parents { get; set; }
public DbSet<Contact> Contacts { get; set; }
public DbSet<Student> Students { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Parent>()
.HasMany(s => s.Students)
.WithMany()
.Map(x =>
{
x.MapLeftKey("login");
x.MapRightKey("student_id");
x.ToTable("StudentParents");
}
);
base.OnModelCreating(modelBuilder);
}
}

Changed the strategy. Made Request have many Contacts. So I added a constructor to the request:
public Request()
{
Contacts = new List<Contact>();
}
public virtual ICollection<Contact> Contacts { get; set; }
Next I changed the contact class:
public int ContactId { get; set; }
public Contact() { }
public virtual Request Request { get; set; }
With this relationship I can pull both Parents and a student from the Contacts associated with the Request.