ApplicationDbContext.OnModelCreating() in .Net Standard 2.0 has MissingMethodException

问题

this is one of the problems that I issued in "Found conflicts between different versions" OR System.MissingMethodException when using aspnetcore.identity, but I wanted to explain it separately with a small example:

SetUp:

A .Net Standard 2.0 Library
A .Net Framework 4.7.2 WebForms application

The .Net standard Library has this Code:

 public class Class1
    {
        public static void doStuff()
        {
            var optionsBuilder = new DbContextOptionsBuilder<ApplicationDbContext>();
            optionsBuilder.UseSqlServer("MyConnectionString");

            var userStore = new UserStore<ApplicationUser, MyRole, ApplicationDbContext, Guid>(
                new ApplicationDbContext(optionsBuilder.Options)
                ); // the userStore.Users property shows already the exception in the debugger

            AspNetUserManager<ApplicationUser> userManager = new AspNetUserManager<ApplicationUser>(
                userStore,
                null,
                new PasswordHasher<ApplicationUser>(),
                new List<UserValidator<ApplicationUser>>() { new UserValidator<ApplicationUser>() },
                null,
                null,
                null,
                null,
                null
                );

            var x = userManager.Users; // exception throw (see next code snipped)
        }
    }

    public class ApplicationDbContext : IdentityDbContext<ApplicationUser, MyRole, Guid>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options)
        {

        }

        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder); // after userManager.Users is called the exception is thrown here
        }
    }

And in the WebForms-Project just:

public partial class _Default : Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Class1.doStuff();
        }
    }

Exception: System.MissingMethodException: 'Methode nicht gefunden: "Microsoft.EntityFrameworkCore.Metadata.Builders.IndexBuilder Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder1.HasIndex(System.Linq.Expressions.Expression1>)".'

Configuration of .Net Standard 2.0 Project:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Identity" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="2.2.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.1.1" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.1" />
    <PackageReference Include="Microsoft.Extensions.Identity.Stores" Version="3.1.1" />
  </ItemGroup>

</Project>

References: https://github.com/dotnet/aspnetcore/issues/8467 Here they say to update to "Microsoft.AspNetCore.Identity" 3.x, but I cannot do that because its not compatible with the .Net Standard 2.0 project and I need that for the WebForms Project.

So my question would be if someone knows a workaround to generate an Usermanager in a different way... I need to Get and Set Users (and validate) using aspnetcore-identity (database etc. is already migrated)

回答1:

So, I have a solution for my problem:

use Microsoft.EntityFrameworkCore.SqlServer version 2.2.6 (NOT 3.1.1 even though its supposed to work with .net standard 2.0...)

And a sequence of

deleting nuget packages
clearing nuget cache
deleting nuget packages on the local computer (in the C:/../Users/.../.nuget folder)
changing the nuget management format to "PackageReference"
cry a lot
reinstalling everything and dealing with warnings helped

(I cant say what exactly the issue was regarding the version-conflicts)

来源：https://stackoverflow.com/questions/59988629/applicationdbcontext-onmodelcreating-in-net-standard-2-0-has-missingmethodexc

标签

asp.net-core

asp.net-identity

.net-standard