分离DbContext项目的ASP.NET Core Minimal Api Scaffolding加载失败修复

问题背景 #

我有一个名为BugDemo的解决方案，包含两个项目：类库项目Data，以及引用Data项目的ASP.NET Core Minimal Api项目Api（已设为启动项目）。通过User Secret在两个项目间共享配置：

{"ConnectionStrings": {"DefaultConnection": "Server=.;Database=BugDemoDb;Integrated Security=true;TrustServerCertificate=true"}}

已通过以下命令成功生成数据库：

dotnet ef migrations add Initialization --startup-project Data --project Data
dotnet ef database update --startup-project Data

但执行Scaffolding命令时：

$env:codegen_trace=1 
dotnet-aspnet-codegenerator minimalapi --project api

出现核心报错：

Scaffolding failed. Could not load information for project ..\Data\Data.csproj

Api项目配置 #

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

  <PropertyGroup>
    <TargetFramework>net7.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UserSecretsId>b3fdc987-781a-4fd4-853d-e279524cb5c6</UserSecretsId>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="7.0.0-rc.1.22427.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="7.0.0-rc.1.22426.7" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="7.0.0-rc.1.22426.7">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="7.0.0-rc.1.22452.2" />
    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.4.0" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Data\Data.csproj" />
  </ItemGroup>

</Project>

using Data;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddDbContext<AppDbContext>(opts =>
{
    opts.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"));
});
var app = builder.Build();

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.MapGet("/", async (AppDbContext ctx) =>
{
    return await ctx.Students.ToListAsync();
});

app.Run();

Data项目配置 #

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

  <PropertyGroup>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <UserSecretsId>b3fdc987-781a-4fd4-853d-e279524cb5c6</UserSecretsId>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="7.0.0-rc.1.22426.7">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="7.0.0-rc.1.22426.7" />
    <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="7.0.0-rc.1.22426.10" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="7.0.0-rc.1.22452.2" />
  </ItemGroup>

</Project>

namespace Data;

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; } = default!;
}

using Microsoft.EntityFrameworkCore;

namespace Data;

public class AppDbContext : DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> opts) : base(opts) { }
    public DbSet<Student> Students { get; set; }
    protected override void OnModelCreating(ModelBuilder mb)
    {
        base.OnModelCreating(mb);
        mb.Entity<Student>().HasData(new Student[]
        {
            new Student{ Id=1,Name="Albert Einstein"},
            new Student{ Id=2,Name="Isaac Newton"},
            new Student{ Id=3,Name="Blaise Pascal"},
            new Student{ Id=4,Name="Nicola Tesla"}
        });
    }
}

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;
using Microsoft.Extensions.Configuration;

namespace Data;

public class AppDesignTimeDbContextFactory : IDesignTimeDbContextFactory<AppDbContext>
{
    public AppDbContext CreateDbContext(string[] args)
    {
        IConfiguration config = new ConfigurationBuilder()
             .AddUserSecrets<Data.AppDesignTimeDbContextFactory>()
             .Build();

        var opts = new DbContextOptionsBuilder<AppDbContext>();
        opts.UseSqlServer(config.GetConnectionString("DefaultConnection"));

        return new AppDbContext(opts.Options);
    }
}

修复方案 #

1. 切换到解决方案根目录执行命令 #

代码生成工具需要识别整个解决方案的项目依赖，确保在解决方案根目录（C:\Projects\BugDemo）下执行命令：

cd C:\Projects\BugDemo
$env:codegen_trace=1 
dotnet-aspnet-codegenerator minimalapi --project Api

2. 显式指定项目参数 #

在命令中明确指定启动项目和数据项目的路径，帮助工具正确识别依赖：

$env:codegen_trace=1 
dotnet-aspnet-codegenerator minimalapi --project Api --startup-project Api --data-project Data

3. 统一CodeGenerator包版本 #

当前使用的Microsoft.VisualStudio.Web.CodeGeneration.Design版本（7.0.0-rc.1.22452.2）与EF Core包版本不一致，将其调整为7.0.0-rc.1.22426.7，然后重新构建整个解决方案：

dotnet build BugDemo.sln

4. 验证项目引用路径 #

确认Api项目中<ProjectReference>的相对路径正确，确保Data项目文件在指定路径下存在，无损坏。

内容的提问来源于stack exchange，提问作者D G