ef-code-first

问题 So I stumbled upon this article earlier today https://blogs.msdn.microsoft.com/azuremobile/2014/05/22/tables-with-integer-keys-and-the-net-backend/ In the article, the author makes a comment that got my attention. He said Note: Typically, when starting from an Entity Framework Code-First model in your .NET Backend, you would use string ids From what I've read, using string Ids can be a performance issue in as your table grows. So I would just like to know if this was just the authors opinion

问题 I have a Person table in my database that has NationalId field. Is there any way to load all Persons with even NationalId , using Ef code first and Linq to entities , without loading all Person s to memory? Somethings like: public bool IsEven(int number) { return number % 2 == 0; } var context = new MyContext(); var personsWithEvenNationalId = context.Persons .Where(x=> IsEven(x.NationalId)) .ToList(); 回答1: You would have to do your check inline var personsWithEvenNationalId = context.Persons

问题 I am working with Entity Framework - Code First, and i have the next context (an extraction at least): public class TestContext : DbContext { public DbSet<User> Users { get; set} public DbSet<Book> Books { get; set} } And in the user's class i have this navigation property: public virtual Collection<Book> Books { get; set} ergo, a user has many books. The problem is that i want to filter the books, but as i have like 500.000 books on my database, i can't afford bringing all the books to

问题 I'm trying to implement encrypted columns in EF4 and using the CTP5 features to allow simple use of POCO's to query the database. Sorry that this is a lot of words, but I hope the below gives enough to explain the need and the problem! So, bit of background, and my progress so far: The intention is that if you query the tables without using our DAL then the data is rubbish, but I don't want the developers to worry about if/when/how the data is encrypted. For simplicity, at this stage I'm

问题 I have two entities like Hat and Owner: +========+ +=========+ |Owner |----------|Hat | +--------| 0/1 1 +---------| |ID | |ID | |Name | |Size | +--------| +---------| |HatId | |OwnerId | +========+ +=========+ (Every Owner has his Hat. Some Hats does not have their owners.) I've created models: public class Owner { [Key] public Int32 ID { get; set; } public String Name { get; set; } public virtual Hat Hat { get; set; } } public class Hat { [Key] public Int32 ID { get; set; } public Int32

问题 I have two Entities Store and Catalog , having many to many relationship using fluent Api. I want to get a Store by id with all the catalogs having status equals to "Published". Below I try to write the following query but not getting the expected results. var store = context.Stores.Include("Catalogs").Where(s => s.StoreID == id && s.Catalogs.Any(c => c.Status == "Published")).SingleOrDefault(); 回答1: What you're asking for there is "give me the store with this ID, but only if it has a

问题 The quick question is "How do I get my Azure database back in sync with my local database?" Details: I have been using entity framework in my project, which really not that different from the ASP.NET MVC 5 sample project, which has Identity 2 built in. There are two database contexts, one called ApplicationDbContext (aspnet_somethingUserDB) from Identity and the other one called StoreInitialTestContext (store_db) that is from my changes. Interestingly, I have each of these contexts in a

问题 I am using EF 4.1 "code first" to create my db and objects. Given: public class Order { public int Id { get; set; } public string Name { get; set; } public virtual OrderType OrderType { get; set; } } public class OrderType { public int Id { get; set; } public string Name { get; set; } } An order has one ordertype. An order type is just a look up table. The values dont change. Using Fluent API: //Order ToTable("order"); HasKey(key => key.Id); Property(item => item.Id).HasColumnName("order_id")

问题 I am a bit confused with Circular dependencies with EF as its seems like everything will just become a circular dependency. Looking at this tutorial public class Blog { public int BlogId { get; set; } public string Name { get; set; } public virtual List<Post> Posts { get; set; } } public class Post { public int PostId { get; set; } public string Title { get; set; } public string Content { get; set; } public int BlogId { get; set; } public virtual Blog Blog { get; set; } } When I run the "code

问题 I have a Candidate entity, with some associations exampled below. I have a view model that doesn't have the reference properties, just the foreign key properties, and I am using AutoMapper to map the view model back to an entity. When I try and save the entity, I get validation errors telling me that e.g. The Title field is required. because although my TitleId has a valid value, Title is still null. public class Candidate { ... [Required] public string RefNum { get; set; } [ForeignKey(