ef-code-first

问题 I have a class that I want to keep meta data for -- there a several interaction scenarios so meta allows me to keep different meta for different interaction types. class Feed() { Guid FeedId { get; set; } ObjectMetaDictionary Meta { get; set; } } I would like EF to serialize this ObjectMetaDictionary and store it as a string/VarChar in the database. When I retrieve a record I want it to be deserialized as an ObjectMetaDictionary. Does EF support this? How can I do it? I am using Entity

问题 I am using MVC 5 with NET Framework 4.5.1. with Code-first. I am also using Migrations with the SQL 2012 server and (localdb)\v11.0. I am in the middle of developing a project using C# and MVC5. During development, I created a lot of new tables in my developmental computer and changed a the "Name" field which I believe the system makes an index for. I added it and deleted it several times. After that, I added a lot iof new unrelated tables, but for some reason, my migrations started giving me

问题 I am building an MVC5 application with ASP.NET Identity 2.0 and EF 6.1.1. This is part of my current Login method: [HttpPost] [AllowAnonymous] [ValidateAntiForgeryToken] public async Task<ActionResult> Login(LoginViewModel model, string returnUrl) { if (!ModelState.IsValid) return View(model); var result = await SignInManager.PasswordSignInAsync(model.UserName, model.Password, model.RememberMe, shouldLockout: true); switch (result) { case SignInStatus.Success: { var user = await UserManager

问题 I am having problems to create an Entity Framework Code-First mapping for the following sample database schema (in SQL Server): Every table contains a TenantId which is part of all (composite) primary and foreign keys (Multi-Tenancy). A Company is either a Customer or a Supplier and I try to model this via Table-Per-Type (TPT) inheritance mapping: public abstract class Company { public int TenantId { get; set; } public int CompanyId { get; set; } public int AddressId { get; set; } public

问题 I'm using Entity Framework CTP5 and Code First. I need to change the Collation for a specific column in SQL Server. I believe the default collation is SQL_Latin1_General_CP1_CI_AS, but I need to change this one column colllation to SQL_Latin1_General_CP1_CS_AS (Case Sensitive). Is there a way to use ModelBuilder in Code First to change a specific column collation? BarDev 回答1: Model builder doesn't allow this but you can create custom database initializer and execute ALTER TABLE command. The

问题 I have a context class that inherits from an abstract base AuditableDbContext : DbContext . The AuditableDbContext takes two parameters, one for the auditor and one for the context to audit into. In the inherited class, I have a default parameterless constructor that calls the other constructors with null parameters and then in the final constructor I call Database.SetInitializer<MyDbContext>(null) after calling the base constructor. The problem is that even when I do this, I still get the db

问题 I have a model with composite key - the row is the key: public class Item { [Key, Column(Order = 0)] public int UserId { get; set; } [Key, Column(Order = 1)] public DateTime? Date { get; set; } } Running the code below it throws an exception DbEntityValidationException with message: The Date field is required. : var it = new Item { Date = null, UserId = 2 }; m_Entities.Items.Add(it); m_Entities.SaveChanges(); // throws exception ( m_Entities is usual DbContext descendant with Items defined as

问题 class Cat { public int CatID; public string Name; public ICollection<Post> Posts; } class Post { public int PostID; public string Name public int CatID; public virtual Cat Parent; } And I want to load all the Catergories with their Posts so: var cats = context.Cat.Include(c => c.Posts); Now I want to limit the number of Posts that are returned, can someone show mw how to do that? I'm using EntityFramework 4.3.1 回答1: It is not possible with eager loading ( Include ) - eager loading returns

问题 My Order class has: public int CustomerId { get; set; } public Customer Customer { get; set; } Do I really need both properties to make a relation working? I am not using disconnected entities, I am using code first approach. 回答1: According to Julia Lerman's book: Programming Entity Framework: DbContext, the difference lies at the difficulty of updating the navigation property. In page 85, She suggests "If there is one thing you can do to make your life easier in N-Tier scenarios, it’s to

问题 I'm trying to work with EF CodeFirst under Oracle with ODP.net. This is my DbContext class: public class MyCEContext : DbContext { public DbSet<Person> Persons { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Person>().ToTable("PERSONS","myce"); } public MyCEContext() : base(new OracleConnection( "Data Source=cebd; User ID=myce; Password=****;"), true) {} } Problem is that when I try to do something like this: MyCEContext context = new