entity-framework-core

问题 Whenever I want to update my EFCore reference to version 3 via NuGet on my NetFramework 4.8 project I get this error. I confirm that I have netcore 3.0 SDK installed on my machine. Could not install package 'Microsoft.EntityFrameworkCore 3.0.0'. You are trying to install this package into a project that targets '.NETFramework,Version=v4.8', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the

问题 By default, EF6 would map a base abstract class and it's derived classes for Table Per Hierarchy (TPH). EF Core no longer follows this logic and requires derived classes to be opted in. The documentation states: By convention, types that are exposed in DbSet properties on your context are included in the model as entities. Entity types that are specified in the OnModelCreating method are also included, as are any types that are found by recursively exploring the navigation properties of other

问题 I´ve tried a lot, but I can´t find what I´m really looking for. This is my case: I have an EF-Core entity with navigation-properties and a viewModel: public class SomeEntity { public Guid Id { get; set; } public virtual NestedObject NestedObject { get; set; } public DateTime Created { get; set; } public DateTime Modified { get; set; } } public class SomeEntityViewModel { public Guid Id { get; set; } public string NestedObjectStringValue { get; set; } public int NestedValueIntValue { get; set;

问题 I'm using EntityFramework Core, Code First and Fluent Api to define model database, and i've follow situation about strategy of map inheritance: public class Person { public int Id { get; set; } public string Name { get; set; } } public class User : Person { public string UserName { get; set; } public string Password { get; set; } } public class Employee : Person { public decimal Salary { get; set; } } public class Customer:Person { public long DiscountPoints { get; set; } } Business logical

问题 Let's say I have two different classes. They share some properties, but also have some individual ones. public class A { // Shared properties public int Id { get; set; } public DateTime CreatedDtm { get; set; } public string CreatedBy { get; set; } // Individual properties public string PhoneNumber { get; set; } public string EmailAddress { get; set; } } public class B { // Shared properties public int Id { get; set; } public DateTime CreatedDtm { get; set; } public string CreatedBy { get;

问题 When I run the Entitfy framework core command add-migration MyMigrationName in a class library I get the following error Could not load file or assembly 'Microsoft.AspNetCore.Hosting.Abstractions, Version=1.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) Funny thing there is no reference in my application to Abstractions. Here is my csproj

问题 When I run the Entitfy framework core command add-migration MyMigrationName in a class library I get the following error Could not load file or assembly 'Microsoft.AspNetCore.Hosting.Abstractions, Version=1.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) Funny thing there is no reference in my application to Abstractions. Here is my csproj

问题 My c# object has a decimal property: public decimal LastPrice { get; set; } While processing my object, the decimal value gets set. For example: LastPrice = 0.091354; I modified my DbContext to increase the decimal precision as explained in another stackoverflow post: protected override void OnModelCreating(ModelBuilder modelBuilder) { foreach (var property in modelBuilder.Model.GetEntityTypes() .SelectMany(t => t.GetProperties()) .Where(p => p.ClrType == typeof(decimal) || p.ClrType ==

问题 EF Core 2.1 introduced support for ambient transactions. The sample creates a new SqlConnection , manually opens it and passes it to the DbContext : using (var scope = new TransactionScope( TransactionScopeOption.Required, new TransactionOptions { IsolationLevel = IsolationLevel.ReadCommitted })) { var connection = new SqlConnection(connectionString); connection.Open(); try { // Run raw ADO.NET command in the transaction var command = connection.CreateCommand(); command.CommandText = "DELETE

问题 AFAIK, there isn't a direct way to delete entities using a predicate such as DbSet.RemoveWhere(() => {}) I tried a few ways to delete and don't know which is the most efficient way to do it. Could you point me in the right direction? The first and most basic thing I tried is: _context.Users.RemoveRange(_context.Users.Where(u => u.Name.Equals("John"))); which loads the user to the memory before deletion. I don't like this approach. The second way I tried is using the Z.EntityFramework.Plus