C#•3y ago

✅ DB context injection not working

hi, i have app like this -

DotNetEnv.Env.Load("../build/");
var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    WebRootPath = "Static"
});

builder.Services.AddMvc();

builder.Services.AddDbContext<MainContext>();
builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options => options.LoginPath = "/login");

var app = builder.Build();

app.UseDefaultFiles();
app.UseStaticFiles();

app.MapControllers();

app.Run();

DotNetEnv.Env.Load("../build/");
var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    WebRootPath = "Static"
});

builder.Services.AddMvc();

builder.Services.AddDbContext<MainContext>();
builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options => options.LoginPath = "/login");

var app = builder.Build();

app.UseDefaultFiles();
app.UseStaticFiles();

app.MapControllers();

app.Run();

DotNetEnv.Env.Load("../build/");
var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    WebRootPath = "Static"
});

builder.Services.AddMvc();

builder.Services.AddDbContext<MainContext>();
builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options => options.LoginPath = "/login");

var app = builder.Build();

app.UseDefaultFiles();
app.UseStaticFiles();

app.MapControllers();

app.Run();

DotNetEnv.Env.Load("../build/");
var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    WebRootPath = "Static"
});

builder.Services.AddMvc();

builder.Services.AddDbContext<MainContext>();
builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options => options.LoginPath = "/login");

var app = builder.Build();

app.UseDefaultFiles();
app.UseStaticFiles();

app.MapControllers();

app.Run();

and when i use MainContext in endpoint as argmuent it says - (screenshot).

example of endpoint

[Route("api/{genre}/{id}")]
public IActionResult IndexGenre(MainContext db, string keyword, int id)
{
    if (keyword == "default")
    {
        Console.WriteLine("1");
        var result = db.Products.Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList();
        return Json(result);
    }
    else if (keyword.Contains("#"))
    {
        string genre = keyword.Substring(0, keyword.Length - 1);
        var result = db.Products.Where(p => p.Type.Contains(genre)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
    else
    {
        var result = db.Products.Where(p => p.Title.Contains(keyword) || p.Description.Contains(keyword)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
}

[Route("api/{genre}/{id}")]
public IActionResult IndexGenre(MainContext db, string keyword, int id)
{
    if (keyword == "default")
    {
        Console.WriteLine("1");
        var result = db.Products.Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList();
        return Json(result);
    }
    else if (keyword.Contains("#"))
    {
        string genre = keyword.Substring(0, keyword.Length - 1);
        var result = db.Products.Where(p => p.Type.Contains(genre)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
    else
    {
        var result = db.Products.Where(p => p.Title.Contains(keyword) || p.Description.Contains(keyword)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
}

[Route("api/{genre}/{id}")]
public IActionResult IndexGenre(MainContext db, string keyword, int id)
{
    if (keyword == "default")
    {
        Console.WriteLine("1");
        var result = db.Products.Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList();
        return Json(result);
    }
    else if (keyword.Contains("#"))
    {
        string genre = keyword.Substring(0, keyword.Length - 1);
        var result = db.Products.Where(p => p.Type.Contains(genre)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
    else
    {
        var result = db.Products.Where(p => p.Title.Contains(keyword) || p.Description.Contains(keyword)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
}

[Route("api/{genre}/{id}")]
public IActionResult IndexGenre(MainContext db, string keyword, int id)
{
    if (keyword == "default")
    {
        Console.WriteLine("1");
        var result = db.Products.Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList();
        return Json(result);
    }
    else if (keyword.Contains("#"))
    {
        string genre = keyword.Substring(0, keyword.Length - 1);
        var result = db.Products.Where(p => p.Type.Contains(genre)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
    else
    {
        var result = db.Products.Where(p => p.Title.Contains(keyword) || p.Description.Contains(keyword)).Skip(id * ITEMS_PER_PAGE).Take(ITEMS_PER_PAGE).ToList(); ;
        return Json(result);
    }
}

xddOP•9/28/23, 10:00 PM

also, it works if put it into Using construction

JakenVeina•9/28/23, 10:07 PM

where is it that you're abusing IoC lifetimes?

JakenVeina•9/28/23, 10:08 PM

cause the error tells you exactly what's happening

JakenVeina•9/28/23, 10:08 PM

you're trying to reuse an existing MainContext instance to perform multiple queries, in parallel

JakenVeina•9/28/23, 10:09 PM

DbContext instances do not support parallel use (I.E. multi-threading)

JakenVeina•9/28/23, 10:10 PM

each incoming HTTP request needs to use its own MainContext instance for performing queries

JakenVeina•9/28/23, 10:10 PM

ASP.NET Core sets all this up for you by creating processing all HTTP requests within their own service scope

JakenVeina•9/28/23, 10:11 PM

and by default, DbContext dependencies are registered as scoped

JakenVeina•9/28/23, 10:12 PM

it's also possible, I suppose, that you're performing multiple queries within the same request, but not

await

await

ing one, so that the end up stepping on each other

JakenVeina•9/28/23, 10:12 PM

however, it doesn't look like you're using asyncasync/

await

await

xddOP•9/28/23, 10:19 PM

i mean, anyway i can't get

xddOP•9/28/23, 10:19 PM

JakenVeina•9/28/23, 10:19 PM

wait...

xddOP•9/28/23, 10:19 PM

it works like this -

app.MapGet("api/{keyword}/{id}", (MainContext db, string keyword, int id) =>
{
    if (keyword == "default")
    {
        Console.WriteLine("1");
        var result = db.Products.Skip(id * 24).Take(24).ToList();
        return Results.Json(result);
    }
    else if (keyword.Contains('#'))
    {
        string genre = keyword.Substring(0, keyword.Length - 1);
        var result = db.Products.Where(p => p.Type.Contains(genre)).Skip(id * 24).Take(24).ToList(); ;
        return Results.Json(result);
    }
    else
    {
        var result = db.Products.Where(p => p.Title.Contains(keyword) || p.Description.Contains(keyword)).Skip(id * 24).Take(24).ToList(); ;
        return Results.Json(result);
    }
});

app.MapGet("api/{keyword}/{id}", (MainContext db, string keyword, int id) =>
{
    if (keyword == "default")
    {
        Console.WriteLine("1");
        var result = db.Products.Skip(id * 24).Take(24).ToList();
        return Results.Json(result);
    }
    else if (keyword.Contains('#'))
    {
        string genre = keyword.Substring(0, keyword.Length - 1);
        var result = db.Products.Where(p => p.Type.Contains(genre)).Skip(id * 24).Take(24).ToList(); ;
        return Results.Json(result);
    }
    else
    {
        var result = db.Products.Where(p => p.Title.Contains(keyword) || p.Description.Contains(keyword)).Skip(id * 24).Take(24).ToList(); ;
        return Results.Json(result);
    }
});

xddOP•9/28/23, 10:19 PM

but don't works if literally same code is in controller

JakenVeina•9/28/23, 10:20 PM

why would you expect it to work the same

xddOP•9/28/23, 10:20 PM

¯\_(ツ)_/¯

JakenVeina•9/28/23, 10:21 PM

if you look at documentation for building controllers, you'll notice it doesn't specify that parameter-injection is supported

JakenVeina•9/28/23, 10:21 PM

not without an additional [FromServices] annotation on each parameter that you want to be populated from the IoC container

xddOP•9/28/23, 10:21 PM

yeah is see

xddOP•9/28/23, 10:21 PM

xddOP•9/28/23, 10:21 PM

ef core was last topic

xddOP•9/28/23, 10:22 PM

im on 6 yet

xddOP•9/28/23, 10:22 PM

there is a bit different way

JakenVeina•9/28/23, 10:22 PM

ef core or not, the normal method of dependency injection for controllers is via the constructor

JakenVeina•9/28/23, 10:23 PM

if you want to use parameter injection, you have to use the annotation I mentioned

JakenVeina•9/28/23, 10:24 PM

https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/dependency-injection?view=aspnetcore-7.0

Dependency injection into controllers in ASP.NET Core

Discover how ASP.NET Core MVC controllers request their dependencies explicitly via their constructors with dependency injection in ASP.NET Core.

xddOP•9/28/23, 10:26 PM

ill look at that later

thx for help,

MainContext db;

public HomeController(MainContext db)
{
    this.db = db;
}

MainContext db;

public HomeController(MainContext db)
{
    this.db = db;
}

works this way

✅ DB context injection not working

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