I'm retrieving data from another database that has already created unique IDs for each "beer" entity. However, when I assign the unique key value from the remote database to a new "beer" object, it gets replaced as soon as the object is inserted into the database.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;
using BeerRecommender.Models.ViewModels;
namespace BeerRecommender.Models
{
public class Beer
{
public Beer()
{
Created = DateTime.Now;
Updated = DateTime.Now;
}
[Key]
public int ID { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public Brewery Brewery { get; set; }
public DateTime Created { get; set; }
public DateTime Updated { get; set; }
public ICollection<City> Cities { get; set; }
public ICollection<Tag> Tags { get; set; }
public Style Style { get; set; }
}
}
I'm using the UnitOfWork pattern.
UnitOfWork.BeerRepository.Insert(beer);
UnitOfWork.Save();
As you already discovered, EF will generate values for int primary keys. To fine tune this behavior you need to mark your key with the DatabaseGenerated attribute (or you can also configure this with the the fluent api's HasDatabaseGeneratedOption method):
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int ID { get; set; }
Related
I have created a class in Model , which will be my database table shown in view.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Runtime.InteropServices;
namespace showtable.Models
{
public class Employee
{
public Guid EmployeeId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public DateTime hiredate { get; set; }
public decimal salary { get; set; }
}
}
now i want to generate a GUID for primary key which is EmployeeId.
how to write it in my controller?
You can do this:
public class Employee
{
public Guid EmployeeId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public DateTime hiredate { get; set; }
public decimal salary { get; set; }
public Employee ()
{
EmployeeId = Guid.NewGuid();
}
}
And then in your controller when you instantiate a new Employee class the you would have the EmployeeId property populated with an GUID.
I want to use the Column data annotation as shown in the sample code below but the compiler (and also IntelliSense) do not seem to know that particular data annotation. I'm using EF 5 in Visual Studio 2010. I installed EF 5 using NuGet. The Required and MaxLength annotations are working.
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
namespace Model
{
public class Destination
{
public int DestinationId { get; set; }
[Required]
public string Name { get; set; }
public string Country { get; set; }
[MaxLength(500)]
public string Description { get; set; }
[Column(TypeName="image")]
public byte[] Photo { get; set; }
public List<Lodging> Lodgings { get; set; }
}
}
What am I missing?
Column is in:
using System.ComponentModel.DataAnnotations.Schema;
the following code:
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;
namespace ConsoleApplication2
{
public class MyContext : DbContext
{
public IDbSet<Entity> Entities { get; set; }
}
public class Entity
{
public int Id { get; set; }
[Column(TypeName = "image")]
public byte[] Photo { get; set; }
}
}
produces:
I'm pulling out my hair here. I've seen the solutions to turning off cascade on delete here, but I can't implement it. I don't know what I'm doing wrong here, but I keep getting the below error:
'System.Data.Entity.ModelConfiguration.EntityTypeConfiguration' does not contain a definition for 'WillCascadeOnDelete' and no extension method 'WillCascadeOnDelete' accepting a first argument of type 'System.Data.Entity.ModelConfiguration.EntityTypeConfiguration' could be found (are you missing a using directive or an assembly reference?)
I've added the necessary namespaces, but I don't see it as an option anywhere in the intellisense and I'm not getting anywhere searching. I'm in VS 2010 MVC 3
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using vf2.Models;
using vf2.Models.LinkTables;
using vf2.Models.Requests;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;
using System.Data.Entity.ModelConfiguration.Configuration;
using System.Data.Entity.ModelConfiguration;
using vf2.Models.Reporting;
using vf2.Models.POSObj;
namespace vf2.Models
{
public class vfContext : DbContext
{
public DbSet<App> Apps { get; set; }
public DbSet<Origin> Origins { get; set; }
public DbSet<WineType> WineTypes { get; set; }
public DbSet<VarType> VarTypes { get; set; }
public DbSet<Wine> Wines { get; set; }
public DbSet<Vintage> Vintages { get; set; }
public DbSet<Distributor> Distributors { get; set; }
public DbSet<Importer> Importers { get; set; }
public DbSet<Producer> Producers { get; set; }
public DbSet<Publication> Publications { get; set; }
public DbSet<Review> Reviews { get; set; }
public DbSet<UserType> UserTypes { get; set; }
public DbSet<Restaurant> Restaurants { get; set; }
public DbSet<WineListChangeRate> WineListChangeRates { get; set; }
public DbSet<MenuChangeRate> MenuChangeRates { get; set; }
public DbSet<WineListCount> WineListCounts { get; set; }
public DbSet<UserObj> UserObjs { get; set; }
public DbSet<ProducerUser> ProducerUsers { get; set; }
public DbSet<DistributorUser> DistributorUsers { get; set; }
public DbSet<RestaurantUser> RestaurantUsers { get; set; }
public DbSet<ProducerEditRequest> ProducerEditRequests { get; set; }
public DbSet<RequestStatus> RequestStatuses { get; set; }
public DbSet<VOAVIRequest> VOAVIRequests { get; set; }
public DbSet<POS> POSs { get; set; }
public DbSet<Cart> Carts { get; set; }
public DbSet<FutureUser> FutureUsers { get; set; }
public DbSet<Doc> Docs { get; set; }
public DbSet<DocType> DocTypes { get; set; }
public DbSet<WineVisit> WineVisits { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Review>().WillCascadeOnDelete(false);
//error here!
base.OnModelCreating(modelBuilder);
}
}
}
"Cascading delete" is a configuration of a relationship, not of an entity/table. Hence WillCascadeOnDelete is a method of CascadableNavigationPropertyConfiguration. Use case example:
modelBuilder.Entity<Review>()
.HasRequired(r => r.Wine)
.WithMany()
.WillCascadeOnDelete(false);
It means that if a wine is deleted from the catalog in the database, it's reviews should not be deleted together with the wine. That's a property of this specific relationship, not of the Reviews table.
In this case trying to delete a wine which has reviews would result in a foreign key constraint violation and exception of course, but that is what you usually want when you disable cascading delete on a required relationship ("Don't allow to delete a wine which has reviews, only allow it for wines which haven't any...").
I created a new asp.net MVC3 application (internet application), and then I added a new model with 3 classes:
public class BizCard
{
[Required]
public string BizCardID { get; set; }
[Required]
public string Name { get; set; }
public string Address { get; set; }
public List<string> PhoneNumbers { get; set; }
[Required]
[DataType(DataType.EmailAddress)]
public string Email { get; set; }
public BizType type { get; set; }
public List<BizService> OfferedServices { get; set; }
public string Description { get; set; }
}
public class BizType
{
public int BizTypeID { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public double Price { get; set; }
}
public class BizService
{
public int BizServiceID { get; set; }
public List<BizType> AllowedBizTypes { get; set; }
public string Name { get; set; }
}
After that, I created a new controller, using the template "Controller with read/write actions and views using entity framework", I set the Model class to be "BizCard" and the data context class to be a new class which is called "BizDB". I was expecting to get a new class named BizDB that inherits from DbContext and includes 3 instances of DbSet:
DbSet<BizCard>, DbSet<BizType>, DbSet<BizService>.
In spite of that, I get the class with only one:
DbSet<BizCard>.
Am I missing something?
You are doing this using EF Code First approach.
1. So, you have to create a context class which should inherit DbContext containing required models as DbSet
2. Build the solution. Otherwise it will not be displayed at controller creation
Then you can create the controller using necessary model and its dbcontext.
I am creating two tables in Visual Web Developer 2010 Express using the following code:
http://imgur.com/a/Mi2Bv (sorry, the forum will not let me, due to a new account, post pictures directly)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace BarApp.Models
{
public class Drinks
{
public int DrinksId { get; set; }
public int EstablishmentsID { get; set; }
public string name { get; set; }
public decimal price { get; set; }
public string description { get; set; }
public string image { get; set; }
public virtual Establishments establishment { get; set; }
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace BarApp.Models
{
public class Promotions
{
public int PromotionsId { get; set; }
public string name { get; set; }
public float discount { get; set; }
public int EstablishmentId { get; set; }
public int DrinkId { get; set; }
public string description { get; set; }
public virtual Establishments establishment { get; set; }
public virtual Drinks drink { get; set; }
}
}
But when I look at the created tables, the Promotions table has actual rows for the public virtual code, whereas the Drinks table does not.
I am able to have the Drinks table function the way I want elsewhere in the project, but I cannot get Promotions to behave the same way because it appears that "public virtual" is giving different results in each table.
I do not understand why my Promotions table is actually creating rows for the public virtual variables. Can someone help me understand?
In this particular situation I was not using the conventional way of referencing the Id field of another table.
I simply needed to change the following:
public int EstablishmentId { get; set; }
public int DrinkId { get; set; }
to the following:
public int EstablishmentsId { get; set; }
public int DrinksId { get; set; }
My tables were created as expected after I made this change.