i'm trying to create a web api with SQL Database server in and when i'm trying to post comes this error

System.InvalidOperationException: Unable to resolve service for type 'BooksApi.Data.BooksdbContext' while attempting to activate 'BooksApi.Controllers.BooksController'. at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired) at lambda_method9(Closure , IServiceProvider , Object[] ) at Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.<>c__DisplayClass7_0.b__0(ControllerContext controllerContext) at Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.<>c__DisplayClass6_0.g__CreateController|0(ControllerContext controllerContext) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync() --- End of stack trace from previous location --- at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger) at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context) at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext) at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Code:Program.cs

using BooksApi.Data;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddControllers();

// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen();

var optionsBuilder = new DbContextOptionsBuilder();
var app = builder.Build();

if (app.Environment.IsDevelopment()){
  app.UseSwagger();
  app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "Books API V1"));}
  app.UseHttpsRedirection();
  app.UseAuthentication();
  app.UseRouting();
  app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
  app.MapControllers();
  app.Run();

public class Startup{
public Startup(IConfiguration configuration)
{
    Configuration = configuration;
}

public IConfiguration Configuration { get; }

public string ConnectionString => Configuration.GetConnectionString("BooksDb");

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<BooksdbContext>(opt => { opt.UseSqlServer(ConnectionString); });
    services.AddHttpContextAccessor();
}
}
public class Program_2
{
public static void Main(string[] args)
    => CreateHostBuilder(args).Build().Run();

// EF Core uses this method at design time to access the DbContext
public static IHostBuilder CreateHostBuilder(string[] args)
    => Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(
            webBuilder => webBuilder.UseStartup<Startup>());}
public class BooksDbContextFactory : IDesignTimeDbContextFactory<BooksdbContext>{
public IConfiguration Configuration { get; }
public BooksdbContext CreateDbContext(string[] args){
    var optionsBuilder = new DbContextOptionsBuilder<BooksdbContext>();
    optionsBuilder.UseSqlServer(("BooksDb"));
    return new BooksdbContext(optionsBuilder.Options);
}

}

Model:

using System;
using System.Collections.Generic;

namespace BooksApi.Models{
public partial class Book
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Genre { get; set; }
    }
}

Context:

 using System;
using System.Collections.Generic;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata;
using BooksApi.Models;
namespace BooksApi.Data{
public partial class BooksdbContext : DbContext
{
    public BooksdbContext(DbContextOptions options)
    {
    }

    public BooksdbContext(DbContextOptions<BooksdbContext> options)
        : base(options)
    {
    }

    public virtual DbSet<Book> Books { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Book>(entity =>
        {
            entity.Property(e => e.Id)
                .ValueGeneratedNever()
                .HasColumnName("id");

            entity.Property(e => e.Genre)
                .HasMaxLength(255)
                .IsUnicode(false)
                .HasColumnName("genre");

            entity.Property(e => e.Name)
                .IsRequired()
                .HasMaxLength(255)
                .IsUnicode(false)
                .HasColumnName("name");
        });

        OnModelCreatingPartial(modelBuilder);
    }

    partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
}

}

Controller:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using BooksApi.Data;
using BooksApi.Models;

namespace BooksApi.Controllers{
[Route("api/[controller]")]
[ApiController]
public class BooksController : ControllerBase
{
    private readonly BooksdbContext _context;

    public BooksController(BooksdbContext context)
    {
        _context = context;
    }

    // GET: api/Books
    [HttpGet]
    public async Task<ActionResult<IEnumerable<Book>>> GetBooks()
    {
        return await _context.Books.ToListAsync();
    }

    // GET: api/Books/5
    [HttpGet("{id}")]
    public async Task<ActionResult<Book>> GetBook(int id)
    {
        var book = await _context.Books.FindAsync(id);

        if (book == null)
        {
            return NotFound();
        }

        return book;
    }

    // PUT: api/Books/5
    // To protect from overposting attacks, see https://go.microsoft.com/fwlink/?linkid=2123754
    [HttpPut("{id}")]
    public async Task<IActionResult> PutBook(int id, Book book)
    {
        if (id != book.Id)
        {
            return BadRequest();
        }

        _context.Entry(book).State = EntityState.Modified;

        try
        {
            await _context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!BookExists(id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return NoContent();
    }

    // POST: api/Books
    // To protect from overposting attacks, see https://go.microsoft.com/fwlink/?linkid=2123754
    [HttpPost]
    public async Task<ActionResult<Book>> PostBook(Book book)
    {
        _context.Books.Add(book);
        try
        {
            await _context.SaveChangesAsync();
        }
        catch (DbUpdateException)
        {
            if (BookExists(book.Id))
            {
                return Conflict();
            }
            else
            {
                throw;
            }
        }

        return CreatedAtAction("GetBook", new { id = book.Id }, book);
    }

    // DELETE: api/Books/5
    [HttpDelete("{id}")]
    public async Task<IActionResult> DeleteBook(int id)
    {
        var book = await _context.Books.FindAsync(id);
        if (book == null)
        {
            return NotFound();
        }

        _context.Books.Remove(book);
        await _context.SaveChangesAsync();

        return NoContent();
    }

    private bool BookExists(int id)
    {
        return _context.Books.Any(e => e.Id == id);
    }
}

}

CodePudding user response：

It's because you pass BooksdbContext context in the BooksController, but context hasn't been registered properly

I will recommend to do this:

public IServiceProvider ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<BooksdbContext>(opt =>
    { 
        opt.UseSqlServer(ConnectionString);
    });
    services.AddHttpContextAccessor();

    return services.BuildServiceProvider();
}