is it possible insert some specific fields from one table to a class in mvc?
for example i have tbl_User . can i insert just field "Name" in "MyClass"?
i wanna pass a model(MyClass) to view that contains some fields of tbl_User .
and i used codefirst.
public class MyClass:tbl_User
{
//i mean can i put some fields of tbl_User instead below code .
//but below code insert all fields of tbl_User
public List<tbl_User> tbl_User { get; set; }
}
Yes, you can; see the code below.
// get /users
public ActionResult Index()
{
using (var db = new YourContext())
{
// We just need to show user name and id will be used to perform actions like edit user ETC. So we have created a reduced model named UserIndexModel.
return db.Users.Select(u => new UserIndexModel { Id = u.Id, Name = u.Name}).ToList();
}
}
Model definitions:
public class User
{
public int Id { get; set; }
public string Name { get; set; }
public string HashPassword { get; set; }
public DateTime CreatedOn { get; set; }
}
public class YourContext : DbContext
{
public DbSet<User> Users { get; set; }
}
View model:
public class UserIndexModel
{
public int Id { get; set; }
public string Name { get; set; }
}
Related
Hello I am new to servers and REST API and am trying to extract data from a dynamically created table and the data does not sync with the data in the database.
I have an sql database from which I extracted an entity database in asp.net web project.
This is an example for GET of one entity class (exists in database):
public class EmployeeBL
{
private FSProject1Entities db = new FSProject1Entities();
public List<Employee> GetEmployees(string fname, string lname, string depID)
{
return GetEmployeeSearchResult(fname, lname, depID);
}
}
And this is an example for a method from a class such as I created in order to combine data from 2 tables:
public class ShiftEmployeeDataBL
{
private FSProject1Entities db = new FSProject1Entities();
private List<ShiftEmployeeDataBL> GetEmployeeByShiftID(int id)
{
List<ShiftEmployeeDataBL> shiftEmpData = new List<ShiftEmployeeDataBL>();
foreach (Employee emp in db.Employee)
{//build list... }
return shiftEmpData;
}
My problem is that db.Employee via this GET request path (ShiftEmployeeData) is old data and via Employee GET request is good data (assuming the data was updated via Employee path).
And vice versa - it would appear that if I update Employee via ShiftEmployeeData class, it would appear as good data for ShiftEmployeeData class and not update for Employee.
I have APIcontrollers for both classes.
what is happening? I feel like I am missing something.
I tried closing cache options in browser.
update with code for elaboration:
entity Employee:
public partial class Employee
{
public int ID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public int StartWorkYear { get; set; }
public int DepartmentID { get; set; }
}
employee update(auto generated by entity model code generation from db):
public void UpdateEmployee(int id, Employee employee)
{
Employee emp= db.Employee.Where(x => x.ID == id).First();
emp.FirstName = employee.FirstName;
emp.LastName = employee.LastName;
emp.StartWorkYear = employee.StartWorkYear;
emp.DepartmentID = employee.DepartmentID;
db.SaveChanges();
}
employeeshiftdata class (not a db table but still in the models folder):
public class EmployeeShiftData
{
public int ID { get; set; } //EmployeeID
public string FirstName { get; set; }
public string LastName { get; set; }
public int StartWorkYear { get; set; }
public string DepartmentName { get; set; }
public List<Shift> Shifts { get; set; }
}
employeeshift GET part of the controller:
[EnableCors(origins: "*", headers: "*", methods: "*")]
public class EmployeeShiftDataController : ApiController
{
private static EmployeeShiftDataBL empShiftDataBL = new EmployeeShiftDataBL();
// GET: api/EmployeeShiftData
public IEnumerable<EmployeeShiftData> Get(string FirstName = "", string LastName = "", string Department = "")
{
return empShiftDataBL.GetAllEmployeeShiftData(FirstName, LastName, Department);
}
//...
}
Would need to see the code that interacts with the database, especially the code that makes the updates.
If the changes are written with Entity Framework, are the models themselves properly related with navigational properties?
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
public List<EmployeeShift> EmployeeShifts { get; set; }
// etc.
}
public class EmployeeShift
{
public int Id { get; set; }
public Int EmployeeID { get; set; }
public Employee Employee { get; set; }
// etc.
}
If those are good, and both models are covered by Entity Framework's context tracking, then both should be updated.
I have these models and context in my application :
public class Department
{
public int Id { get; set; }
public string Name { get; set;}
public virtual ICollection<Student> Students { get; set; }
}
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Department Department { get; set; }
}
public class TestContext : DbContext
{
public DbSet<Student> Students { get; set; }
public DbSet<Department> Departments { get; set; }
}
Below is my code in Program.cs class :
class Program
{
static void Main(string[] args)
{
using (var context = new TestContext())
{
var students = context.Students.SqlQuery("Select * from dbo.Students").ToList();
context.Departments.Load();
Console.WriteLine(students[0].Department.Name);
Console.ReadLine();
}
}
}
Although related object - Department is loaded in the context by the line - context.Departments.Load(), still when the department name is printed in console entity framework fires a query in the database to fetch the related object. Shouldnt this query for related object fetching not be fired since the objects are already loaded in the context. ?
If i change the code to below -
var students = context.Students.ToList();
context.Departments.Load();
Console.WriteLine(students[0].Department.Name);
Then when u access student[0].Department.Name , Ef doestnot fire a sql query to load department property.
Apparently Change Tracker relationship fix-up doesn't work with the combination of Independent Associations and raw SQL queries.
To fix just add Foreign Key property to Student. eg
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public int DepartmentId { get; set; }
public virtual Department Department { get; set; }
}
I have a little problem when I try to save an item in my DB using EntityFramework.
My classes looks like:
public partial class Site
{
public int Id { get; set; }
public string Name { get; set; }
public string LongName { get; set; }
public string Adress { get; set; }
public City City { get; set; }
public Country Country { get; set; }
public string VATNumber { get; set; }
}
public class Country
{
public int CountryId { get; set; }
public string Name { get; set; }
public string IsoCode { get; set; }
}
And when I try to create a new site in my controller it works, but when I try to add a link to an existing Country :
if (SiteProvider.GetSiteByName(Site.Name) == null)
{
Site.Country = CountryProvider.GetCountryById(1);//it's working, i see the link to the right country
SiteProvider.Create(Site);
}
public static void Create(Site Site)
{
using (MyDBContext Context = new MyDBContext())
{
Context.Site.Add(Site);
Context.SaveChanges(); //here is the problem
}
}
I got this error:
SqlException: Cannot insert explicit value for identity column in
table 'Country' when IDENTITY_INSERT is set to OFF
Thanks in advance for your help.
Add CountryId property to Site class and when adding a new Site set CountryId instead of Country property
public int CountryId { get; set; }
[ForeignKey("CountryId")]
public Country Country{ get; set; }
You have a slight issue with your use of contexts here. You have used one DBContext instance to load the country (where this country object will be tracked) and then a second DBContext to save the site (where the first country object is a property).
It is preferable to perform all your operations for a single unit of work by using one DB context (that would be shared between your classes) and the responsibility for disposing of it to be handled outside your repository layer.
As title say, i got problem with a query in Asp.net mvc 3 EF.
I got 2 tables with 1 to many relationship.
table1 Users int user_ID string username
table2 Friends int friendshipID int user_ID int friend_ID
The controller:
// // GET: /User/Details/5
public ViewResult Details(int id)
{
User user = db.Users.Include("Friends").FirstOrDefault(u => u.user_ID == id);
//Also for each friend get the User:
foreach (var friend in user.Friends.ToList())
{
friend.User = db.Users.Find(friend.friend_ID);
}
return View(user);
}
The view "details":
#model Social2.Models.User
#{
ViewBag.Title = "Details";
}
<h2>Details</h2>
<div class="display-field">
#foreach (var friend in #Model.Friends)
{
#friend.User.username;
}
</div>
Context:
public partial class ASPNETDBEntities : DbContext
{
public ASPNETDBEntities()
: base("name=ASPNETDBEntities")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}
public DbSet<aspnet_Users> aspnet_Users { get; set; }
public DbSet<Friend> Friends { get; set; }
public DbSet<User> Users { get; set; }
}
user model:
public partial class User
{
public User()
{
this.Friends = new HashSet<Friend>();
}
[Key]
public int user_ID { get; set; }
public System.Guid user_UniqueID { get; set; }
public string username { get; set; }
public virtual aspnet_Users aspnet_Users { get; set; }
public virtual ICollection<Friend> Friends { get; set; }
}
friend model
public partial class Friend
{
public int friendship_ID { get; set; }
public int user_fr_ID { get; set; }
public int friend_ID { get; set; }
public virtual User User { get; set; }
}
The problem is, when i go to ~/user/details/1, the view show only one(the last one) friend.For every user it shows their last friend. How to show them all ?
Your database must have two relationships defined like so:
If you create an Entity Model from this schema you also get two one-to-many relationships. And when you apply the DBContext T4 template to this model you should get POCO classes like so:
public partial class Users
{
public Users()
{
this.Friends = new HashSet<Friends>();
this.Friends1 = new HashSet<Friends>();
}
public int user_ID { get; set; }
public string username { get; set; }
public virtual ICollection<Friends> Friends { get; set; }
public virtual ICollection<Friends> Friends1 { get; set; }
}
public partial class Friends
{
public int friendship_ID { get; set; }
public int user_fr_ID { get; set; }
public int friend_ID { get; set; }
public virtual Users Users { get; set; }
public virtual Users Users1 { get; set; }
}
Users.Friends and Friends.Users form a pair for the first relationship and Users.Friends1 and Friends.Users1 are a pair for the second relationship. (You can rename the navigation properties in the model designer to make the names more meaningful.) Your query would look like this then (you can include a "second level" and don't need the loop as you did in your example):
public ViewResult Details(int id)
{
// important to use User1 in Include, not User
User user = db.Users.Include("Friends.User1")
.FirstOrDefault(u => u.user_ID == id);
return View(user);
}
With DbContext you can also use the strongly typed version of Include:
Include(u => u.Friends.Select(f => f.User1))
I think the problem is mapping of the class Friend.
try change to:
public partial class Friend
{
[Key]
public int friendship_ID { get; set; }
public int user_fr_ID { get; set; }
public int friend_ID { get; set; }
[ForeignKey("friend_ID")]
public virtual User User { get; set; }
}
I think the problem is here
User user = db.Users.Include("Friends").FirstOrDefault(u => u.user_ID == id);
FirstOrDefault gives only one record.
Sample class structure
class Order
{
public int Id { get; set; }
public DateTime Date { get; set; }
public List<OrderDetail> Details { get; set; }
}
class OrderDetail
{
public int Id { get; set; }
public int Qty { get; set; }
public Item Item { get; set; }
}
class Item
{
public int Id { get; set; }
public string Name { get; set; }
}
class ElectronicItem : Item
{
public MoreDetail Detail { get; set; }
}
class MoreDetail
{
public int Id { get; set; }
public string SomeData { get; set; }
}
In order to populate order object with all navigational properties, I wrote
context.Orders.Include("Details").Include("Details.Item")
I also want to load MoreDetail object, hence I tried
context.Orders.Include("Details").Include("Details.Item.Detail")
It didn't work. How to load complete Order object?
It is currently not possible but it is feature requested by community on User DataVoice as you already found. There is also related bug on MS Connect.
You simply cannot eager load navigation properties of derived types but you can load them with separate query:
var moreDetails = context.MoreDetails;
EF should automatically fix your navigation properties. If you use filtering on orders in your original query you must apply that filter in more details query as well:
var moreDetails = cotnext.MoreDetials.Where(m => m.Item.Order ....);