entity-framework-core

问题 I am trying to port everything from Entity Framework 6.3 to Entity Framework Core 2.1.2 and this is my first experience with EF Core. I have 2 projects one is my core or infrastructure project with all the entity models, DB Context and repositories and the other one is an asp.Net MVC which is my startup project and using all the services from the core project. Both projects are using .NetStandard Library 2.0.3 and targeted .Net Framework 4.6.2. And I have .Net Core SDK 2.2 on my machine. The

问题 I am trying to join two tables in EntityFramework Core using linq syntax in the following way: var results = dc.EntityA.Join(dc.EntityB, a => a.StringProperty, b => b.StringProperty, (a, b) => DoSomeStuff(a, b)).ToList(); Where StringProperty is a string column in the database. I am getting the error {"Invalid column name 'EntityId'."} I found this similar question Entity Framework: Invalid column name 'OrganizationStructure_ID' where it is suggested to set the foreignkeys during

问题 I am trying to define relationships between tables, but getting the following error: Introducing FOREIGN KEY constraint 'FK_QProducts_Quotes_QuoteId' on table 'QProducts' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.Could not create constraint or index. See previous errors. This is how my tables look like: What I am trying to achieve: A. Client creates an inquiry and adds products and quantities that he

问题 This is an ASP.Net Core Web API Project, using EntityFrameWorkCore. I need to convert TotalLoggedInTime (format: 139:05:40) to Hours and Sum the hours and assign it to logonHours, it fails on that line. The first line for callsOffered works fine. C# Code: internal void Hydrate(DbSet<MyObj> myObj) { string callsOffered = myObj.Sum(a => a.CallsPresented).ToString(); string logonHours = myObj.Sum(a => TimeSpan.Parse(a.TotalLoggedInTime).TotalHours).ToString(); } SQL Table SELECT total_logged_in

问题 Is there any possible way to create migration on runtime in efcore. context.Database.Migrate(); Before this code, I need a code that, when I started my app, should create a migration about diff between postgresql database tables and ef models. Is there any way to do this? PM> enable-migrations PM> add-migration initial PM> update-database I dont want to use these ones. I want to make these code's jobs on runtime. I hope I could explain myself clearly. 回答1: Note, you need to re-compile the app

问题 I'm trying to implement a custom IMethodCallTranslator in EF Core 3.1 with the Sqlite provider. I have created: An extension method off of this DbFunctions which is called at query time An implementation of IMethodCallTranslator which is Translate not called A derived RelationalMethodCallTranslatorProvider which I'm passing an instance of my IMethodCallTranslator . This constructor is hit. I also tried overriding RelationalMethodCallTranslatorProvider.Translate and this was not hit. An

问题 EF Core 3.0 I have the following (simplified) entities in my domain: class ApplicationUser { public int Id { get; set; } public string UserName { get; set; } // other properties } [Owned] class Stamp { public string Username { get; set; } public ApplicationUser User { get; set; } DateTime DateTime { get; set; } } class Activity { public Stamp Created { get; set; } public Stamp Modified { get; set; } // other properties } It's not particularly relevant, but it's worth mentioning that

问题 Postgres database has multiple schemes like company1, company2, ... companyN Browser sends cookie containing scheme name . Data access operations should occur in this scheme. Web application user can select different scheme. In this case different cookie value is set. Npgsql EF Core Data provider is used. ASP NET MVC 5 Core application registers factory in StartUp.cs : public void ConfigureServices(IServiceCollection services) { services.AddHttpContextAccessor(); services.AddScoped

问题 I'm trying to set up a one to many relationship in Entity Framework Core using the Fluent API with no success. I have two objects called Message and Source and are defined as public class Message { public int ID { get; set; } public int FromUserID { get; set; } public int ToUserID { get; set; } public int SourceID { get; set; } public int Priority { get; set; } public string Subject { get; set; } public string MessageBody { get; set; } public DateTime DateTimeCreated { get; set; } public

问题 I am using EF Core 2.1. I have a Group object that has the following properties: int GroupId int? ParentGroupId Group ParentGroup The object references the GroupId of its parent using the ParentGroupId property. The depth of the hierarchy is not known when querying. How can I retrieve the entire hierarchy? I've tried the following, which will get me three levels deep, but how can I get all levels of the hierarchy without knowing the depth? Do I need to rely on a stored proc? var group = await