如何让ASP.NET Core+Angular应用引用带EDMX的.NET类库（不改动现有MVC项目）

Hey there, let's break this down step by step so you can reuse your existing ADO.NET/EDMX project without touching your existing MVC app or forcing changes to other systems. The core idea is to turn your EDMX project into a shared class library that both your existing MVC app and new Core app can reference—no need to regenerate EF models (which caused your earlier headache).

Step 1: Prepare Your EDMX Project for Sharing #

First, make sure your EDMX project is set up as a class library (if it isn't already):

• Right-click the EDMX project → Properties → Application tab.
• If it's targeting .NET Framework 4.x, upgrade it to .NET Standard 2.0 (this is safe because .NET Framework 4.6.1+ and all modern .NET Core versions support .NET Standard 2.0—your existing MVC app will keep working without any changes).
• Save the changes and rebuild the EDMX project.

Step 2: Reference the EDMX Library in Your New ASP.NET Core Project #

1. Open your solution with the new Angular + ASP.NET Core app.
2. Right-click the Core project → Add → Project Reference.
3. Select your EDMX class library from the list and click OK.

Step 3: Configure Connection Strings & DbContext #

Next, set up your Core app to use the existing EDMX DbContext:

1. In your Core project's appsettings.json, add the same connection string your MVC app uses (copy it from your MVC app's web.config to avoid typos):

"ConnectionStrings": {
  "YourDbContextName": "Server=your-db-server;Database=your-db-name;Trusted_Connection=True;TrustServerCertificate=True;"
}

2. Update your EDMX's DbContext to support .NET Core's dependency injection (this won't break your MVC app):
   • Open the .tt file associated with your EDMX (e.g., YourDbContext.tt).
   • Find the constructor section and modify it to include a constructor that accepts DbContextOptions:

public <#=code.Escape(container)#>(DbContextOptions<<#=code.Escape(container)#>> options)
    : base(options)
{
}

• Rebuild the EDMX project—your MVC app can still use the existing无参 constructor, while the Core app will use this new one.

3. Register the DbContext in your Core project's Program.cs:

builder.Services.AddDbContext<YourEDMXDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("YourDbContextName")));

Step 4: Use the EDMX to Fetch User Data #

Now you can access user data in your Core app, either directly via the DbContext or by wrapping it in a service for better separation:

Option A: Direct DbContext Access in Controllers #

Create an API controller to expose user data to your Angular frontend:

[ApiController]
[Route("api/[controller]")]
public class UsersController : ControllerBase
{
    private readonly YourEDMXDbContext _dbContext;

    public UsersController(YourEDMXDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    [HttpGet]
    public IActionResult GetAllUsers()
    {
        var users = _dbContext.Users.ToList();
        return Ok(users);
    }
}

Option B: Wrap in a Service (Recommended) #

For cleaner code and better reusability, add a service to your EDMX class library:

public class UserService
{
    private readonly YourEDMXDbContext _dbContext;

    public UserService(YourEDMXDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    public List<User> GetAllUsers()
    {
        return _dbContext.Users.ToList();
    }

    // Add other user-related methods here (e.g., GetUserById, UpdateUser)
}

Then register the service in Program.cs:

builder.Services.AddScoped<UserService>();

And use it in your controller:

[ApiController]
[Route("api/[controller]")]
public class UsersController : ControllerBase
{
    private readonly UserService _userService;

    public UsersController(UserService userService)
    {
        _userService = userService;
    }

    [HttpGet]
    public IActionResult GetAllUsers()
    {
        var users = _userService.GetAllUsers();
        return Ok(users);
    }
}

Troubleshooting Common Issues #

• Circular Reference Serialization Errors: If you get JSON serialization issues with related entities, configure your Core app's JSON options in Program.cs:

builder.Services.AddControllersWithViews()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles;
    });

• Framework Compatibility: If you can't upgrade your EDMX project to .NET Standard, you can target .NET Framework 4.x in your Core app (but this is less ideal for long-term maintenance).

This approach keeps your existing MVC app untouched, lets your new Angular/Core app reuse the existing EDMX database layer, and avoids the need to regenerate EF models (which was causing cross-app changes before).

内容的提问来源于stack exchange，提问作者Bartvandee