entity-framework-core

问题 I am trying this activity to clone from existing .edmx project to code first. I have two entities. I want to have many to many relation without creating a new table. I am using EF Core 2.0 code first approach. Please find below the entity i have created. I am not sure whether is this is the right way to do this. I would like to have the foreign key column on both the tables ie. WorkflowId and WorkCaseId on WorkCase and Workflow tables respectively. public class WorkCase { [Key] public int

问题 I am having difficulty inserting data with its related entities. public class Status : Entity, IAggregateRoot { //other properties public readonly List<Video> _videos; public readonly List<Photo> _photos; } -- public class Log : Entity, IAggregateRoot { //other properties public readonly List<Video> _videos; public readonly List<Photo> _photos; public readonly List<Sound> _audios; } -- public class Photo : Entity, IAggregateRoot { //other properties public string Type { get; set; } public int

问题 I have designed my models so that it should not be created with a null parameter. For example, if I want to enforce that every Post should have a corresponding Blog , then my models will look like: public class Post { private Post() { } public Post(Blog blog) { Blog = blog ?? throw new ArgumentNullException(nameof(blog)); } public int PostId { get; private set; } public Blog Blog { get; private set; } } public class Blog { public int BlogId { get; private set; } } This way, it will throw an

问题 I'm trying to create a simple query using EFCore, returning the list of people i'm conversing with, and the last message that was sent between the two of us (pretty much like how it's displayed on Facebook Messenger or Whatsapp). I created the linq query but its generating one hell of an sql query. I'm trying to optimize the linq query to generate a better sql, so here comes the full story: 0. The Two Entities: Visitors and ChatMessages The Visitor contains the visitor information, and the

问题 I try do adhere DDD principles on C# collections see more here And I notice that the model builder method for initial seed HasData relies on the Add Method of ICollection . There is any way to circumvent or trick that method when is called from database update / migrate process? All I had done until now to trick it follows this path. 1) Create a wrapper around the ICollection named ReadOnlyKollection 2) Have a private ICollection on the model, to avoid exposing to the outside world the

问题 Is it possible to use EF Core FromSql to execute a stored procedure that has optional parameters? I have been testing out a simple scenario to use as a template for updating old EF6 calls to EF Core calls. The test example I am using as a proof of concept: CREATE PROCEDURE [dbo].[TestNullableParameters] @addressId int = null, @city nvarchar(100) = null, @createdByUserId int AS BEGIN select * from CRM..Address a where (@addressId is null or a.AddressId = @addressId) and (@city is null or a

问题 I have an existing database which I am accessing from 2 separate projects, one an ASP.NET MVC 5 project, and one running .NET Core 2.1 using the respective Entity Framework verisons in each. My problem is that the query that I'm using on the MVC project is being translated incorrectly on the .NET Core project My 2 models are as follows, a Job which has 0 or more Workorders: public virtual DbSet<Job> Jobs { get; set; } public virtual DbSet<WorkOrder> WorkOrders { get; set; } public class Job {

问题 I have an entity that owns another entity public class Entity1 { [Key] [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public virtual int ID { get; set; } public string Property { get; set; } public Entity2 Description { get; set; } } public class Entity2 { public string Test { get; set; } } and I need to create an index on Entity1.Property and Entity2.Test. The configuration is like this builder.OwnsOne(pt => pt.Description); builder.HasIndex(p => new { p.Property, p.Description.Test }

问题 I am creating an API using ASP.NET5 and Entity Framework 7.0.0-beta 6, and when I try to execute various updates in several requests, I get this Exception: 'Company' cannot be tracked because another instance of this type with the same key is already being tracked. For new entities consider using an IIdentityGenerator to generate unique key values. This is my code: public class MrBellhopContext : DbContext { public DbSet<Company> Company { get; set; } protected override void OnModelCreating

问题 I am in the process of upgrading to EF Core 3.0 and .NET Core 3.0, but some of my queries stopped working. Here is an example: I have a table called Bins , I have another table which is called BinItems , now it has, of course, a one to many relationship. BinItems has a property called Qty , and I want to sum up all the Qty from BinItems based on criteria given by the client in a filter. So here is the code: var query = _binRepository.Table; if (filter.LastRecountDate != null) { query = query