entity-framework

问题 I'm a rookies of EF so, sorry for my perhaps foolish question. I've 2 entities without any relationship (VS does not load the join and I can't manually add it because the primary key of the child uses a derivated key of its parent). Example Entity master Products keys GKey_K, Product_K fields ..... Entity detail GenericInformation keys GKey_K, GI_K fields Product_K, .... Well, my question is simple (I hope also my english!), how I can read only the products that have some reference on

问题 I'm a rookies of EF so, sorry for my perhaps foolish question. I've 2 entities without any relationship (VS does not load the join and I can't manually add it because the primary key of the child uses a derivated key of its parent). Example Entity master Products keys GKey_K, Product_K fields ..... Entity detail GenericInformation keys GKey_K, GI_K fields Product_K, .... Well, my question is simple (I hope also my english!), how I can read only the products that have some reference on

问题 I need to take (for example, 2), 2 messages from a conversation I dont care about how my list looks like, but i want only 2 messages from id 1, 2 messages from id2, and go on example: id = idConversation Id | MessageId | Message ---|-----------|-------- 1 | 1 | "asd" 1 | 2 | "asd2" 1 | 3 | "asd3" 1 | 4 | "asd4" 2 | 5 | "asd5" 3 | 6 | "asd6" 3 | 7 | "asd7" 3 | 8 | "asd8" 3 | 9 | "asd9" 3 | 10 | "asd10" 4 | 11 | "asd11" 4 | 12 | "asd12" 4 | 13 | "asd13" and i want that Id MessageId Message ---|

问题 When I create this query: context.Orders.Where(x => context.Customers.Where(c => c.PersonID == 10002).Select(c => c.CustomerID.Value).Contains(x.CustomerID.Value)).ToList(); I Expect it to create a query like this: select * from Orders where CustomerID in (select CustomerID from Customers Where PersonID = 10002) But the generated query is equivalent to: select * from Orders o where Exists(select 1 from Customers c where c.PersonID = 10002 and c.CustomerID = o.CustomerID) this is a very simple

问题 I am a little confused on the code first entity framework database. I created a new DbContext and class that I will be storing in that context, like this: namespace MyProject.Subproject.Something { public class MyItem { public string One { get; set; } public string Two { get; set; } [Key] public string Three { get; set; } public string Four { get; set; } } public class MyAppData : DbContext { public DbSet<MyItem> MyItems { get; set; } } } I know that it's working since I can do this without

问题 I have got 3 table. For instance Client , Company and Address . Client has got ref to Company. Company has got 2 nullable refs to Address (Billing and Shipping), so Address may not exist in some case. I need make join query, but in case when Company.BillingAddress or Company.ShippingAddress equals null , I don't get all data). I tried it (but it's wrong query): var res = (from client in context.Clients join clientCompany in context.Companies on client.ClientCompanyId equals clientCompany.Id

问题 I'm using Entity Framework and MVC3, and my problem is that I can't scaffold Controllers if the class inherits from another Class. Example: This is Base Class using System; using System.Collections.Generic; namespace CRMEntities { public partial class Company { public int Id { get; set; } } } This is Lead Class (Child) using System; using System.Collections.Generic; namespace CRMEntities { public partial class Lead : Company { public Lead() { this.Status = 1; this.IsQualified = false; }

问题 I realized this has been asked already, but the solutions I've read don't seem to make a difference so far. I'm using Entity Framework 6.1 and AutoMapper 3.1.1. Taking the following objects: Company and CompanyListItem ; I try this: Mapper.Configure<Company, CompanyListItem>(); Well, when I try to do the actual mapping it crashed and burned with an exception that there's no mappings defined. I know this is caused because of the proxy objects created by Entity Framework. One solutions I've

问题 I realized this has been asked already, but the solutions I've read don't seem to make a difference so far. I'm using Entity Framework 6.1 and AutoMapper 3.1.1. Taking the following objects: Company and CompanyListItem ; I try this: Mapper.Configure<Company, CompanyListItem>(); Well, when I try to do the actual mapping it crashed and burned with an exception that there's no mappings defined. I know this is caused because of the proxy objects created by Entity Framework. One solutions I've

问题 Using complex types the default column naming convention uses underscore. That means having type defined that way: [ColmplexType] public class Contact { string Email {get;set;} string Post {get;set;} } public EntityN { //... public Contact Contact {get;set;} } we will get columns named such way Contact_Email nvarchar(max) Contact_Post nvarchar(max) We of course could configure each column name separately using ColumnAttribute or Context.Properties mapping, but do we have a possibility to