实例化 dbcontext 时出错

Question

当我尝试在主控制器中实例化数据库时，asp.net mvc 项目出现错误。我将向您展示家庭控制器以及生成的错误和 BirdProjectContext.cs 保存数据库上下文的文件。

using BirdProject.Model;
using BirdProject.Models;
using Microsoft.AspNetCore.Mvc;
using System.Diagnostics;

namespace BirdProject.Controllers
{
    public class HomeController : Controller
    {
        private readonly ILogger<HomeController> _logger;
        private readonly BirdProjectContext _db;

        public HomeController(ILogger<HomeController> logger, BirdProjectContext db)
        {
            _logger = logger;
            _db = db;
        }

        public IActionResult Index()
        {
            return View();
        }

        public IActionResult Privacy()
        {
            return View();
        }

        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }
    }
}

这是错误：

这是解决方案的结构：

这是BirdProjectContext.cs里面的数据：

using System;
using System.Collections.Generic;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata;

namespace BirdProject.Model
{
    public partial class BirdProjectContext : DbContext
    {
        public BirdProjectContext()
        {
        }

        public BirdProjectContext(DbContextOptions<BirdProjectContext> options)
            : base(options)
        {
        }
        public virtual DbSet<AspNetRole> AspNetRoles { get; set; } = null!;
        public virtual DbSet<AspNetRoleClaim> AspNetRoleClaims { get; set; } = null!;
        public virtual DbSet<AspNetUser> AspNetUsers { get; set; } = null!;
        public virtual DbSet<AspNetUserClaim> AspNetUserClaims { get; set; } = null!;
        public virtual DbSet<AspNetUserLogin> AspNetUserLogins { get; set; } = null!;
        public virtual DbSet<AspNetUserToken> AspNetUserTokens { get; set; } = null!;
        public virtual DbSet<BirdBto> BirdBtos { get; set; } = null!;
        public virtual DbSet<Person> People { get; set; } = null!;
        public virtual DbSet<SpotLog> SpotLogs { get; set; } = null!;

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
#warning To protect potentially sensitive information in your connection string, you should move it out of source code. You can avoid scaffolding the connection string by using the Name= syntax to read it from configuration - see https://go.microsoft.com/fwlink/?linkid=2131148. For more guidance on storing connection strings, see http://go.microsoft.com/fwlink/?LinkId=723263.
                optionsBuilder.UseSqlServer("Server=localhost\SQLEXPRESS;Database=BirdProject;Trusted_Connection=True;");
            }
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<AspNetRole>(entity =>
            {
                entity.HasIndex(e => e.NormalizedName, "RoleNameIndex")
                    .IsUnique()
                    .HasFilter("([NormalizedName] IS NOT NULL)");

                entity.Property(e => e.Name).HasMaxLength(256);

                entity.Property(e => e.NormalizedName).HasMaxLength(256);
            });

            modelBuilder.Entity<AspNetRoleClaim>(entity =>
            {
                entity.HasIndex(e => e.RoleId, "IX_AspNetRoleClaims_RoleId");

                entity.HasOne(d => d.Role)
                    .WithMany(p => p.AspNetRoleClaims)
                    .HasForeignKey(d => d.RoleId);
            });

            modelBuilder.Entity<AspNetUser>(entity =>
            {
                entity.HasIndex(e => e.NormalizedEmail, "EmailIndex");

                entity.HasIndex(e => e.NormalizedUserName, "UserNameIndex")
                    .IsUnique()
                    .HasFilter("([NormalizedUserName] IS NOT NULL)");

                entity.Property(e => e.Email).HasMaxLength(256);

                entity.Property(e => e.NormalizedEmail).HasMaxLength(256);

                entity.Property(e => e.NormalizedUserName).HasMaxLength(256);

                entity.Property(e => e.UserName).HasMaxLength(256);

                entity.HasMany(d => d.Roles)
                    .WithMany(p => p.Users)
                    .UsingEntity<Dictionary<string, object>>(
                        "AspNetUserRole",
                        l => l.HasOne<AspNetRole>().WithMany().HasForeignKey("RoleId"),
                        r => r.HasOne<AspNetUser>().WithMany().HasForeignKey("UserId"),
                        j =>
                        {
                            j.HasKey("UserId", "RoleId");

                            j.ToTable("AspNetUserRoles");

                            j.HasIndex(new[] { "RoleId" }, "IX_AspNetUserRoles_RoleId");
                        });
            });

            modelBuilder.Entity<AspNetUserClaim>(entity =>
            {
                entity.HasIndex(e => e.UserId, "IX_AspNetUserClaims_UserId");

                entity.HasOne(d => d.User)
                    .WithMany(p => p.AspNetUserClaims)
                    .HasForeignKey(d => d.UserId);
            });

            modelBuilder.Entity<AspNetUserLogin>(entity =>
            {
                entity.HasKey(e => new { e.LoginProvider, e.ProviderKey });

                entity.HasIndex(e => e.UserId, "IX_AspNetUserLogins_UserId");

                entity.Property(e => e.LoginProvider).HasMaxLength(128);

                entity.Property(e => e.ProviderKey).HasMaxLength(128);

                entity.HasOne(d => d.User)
                    .WithMany(p => p.AspNetUserLogins)
                    .HasForeignKey(d => d.UserId);
            });

            modelBuilder.Entity<AspNetUserToken>(entity =>
            {
                entity.HasKey(e => new { e.UserId, e.LoginProvider, e.Name });

                entity.Property(e => e.LoginProvider).HasMaxLength(128);

                entity.Property(e => e.Name).HasMaxLength(128);

                entity.HasOne(d => d.User)
                    .WithMany(p => p.AspNetUserTokens)
                    .HasForeignKey(d => d.UserId);
            });

            modelBuilder.Entity<BirdBto>(entity =>
            {
                entity.HasKey(e => e.MetalRing);

                entity.ToTable("BirdBTO");

                entity.Property(e => e.MetalRing)
                    .HasMaxLength(50)
                    .IsUnicode(false)
                    .HasColumnName("metalRing");

                entity.Property(e => e.ColourPos)
                    .HasMaxLength(20)
                    .IsUnicode(false)
                    .HasColumnName("colourPos");

                entity.Property(e => e.ColourRing)
                    .HasMaxLength(20)
                    .IsUnicode(false)
                    .HasColumnName("colourRing");

                entity.Property(e => e.Latitude).HasColumnName("latitude");

                entity.Property(e => e.Longitude).HasColumnName("longitude");

                entity.Property(e => e.MetalPos)
                    .HasMaxLength(20)
                    .IsUnicode(false)
                    .HasColumnName("metalPos");

                entity.Property(e => e.Sex)
                    .HasMaxLength(1)
                    .IsUnicode(false)
                    .HasColumnName("sex");

                entity.Property(e => e.Specie)
                    .HasMaxLength(30)
                    .IsUnicode(false)
                    .HasColumnName("specie");
            });

            modelBuilder.Entity<Person>(entity =>
            {
                entity.HasKey(e => e.Email);

                entity.ToTable("Person");

                entity.Property(e => e.Email)
                    .HasMaxLength(50)
                    .IsUnicode(false)
                    .HasColumnName("email");

                entity.Property(e => e.FullName)
                    .HasMaxLength(50)
                    .IsUnicode(false);
            });

            modelBuilder.Entity<SpotLog>(entity =>
            {
                entity.HasKey(e => e.SpotId);

                entity.ToTable("SpotLog");

                entity.Property(e => e.SpotId)
                    .ValueGeneratedNever()
                    .HasColumnName("spotID");

                entity.Property(e => e.Date)
                    .HasColumnType("date")
                    .HasColumnName("date");

                entity.Property(e => e.Email)
                    .HasMaxLength(50)
                    .IsUnicode(false)
                    .HasColumnName("email");

                entity.Property(e => e.Latitude).HasColumnName("latitude");

                entity.Property(e => e.Longitude).HasColumnName("longitude");

                entity.Property(e => e.MetalRing)
                    .HasMaxLength(50)
                    .IsUnicode(false)
                    .HasColumnName("metalRing");

                entity.HasOne(d => d.EmailNavigation)
                    .WithMany(p => p.SpotLogs)
                    .HasForeignKey(d => d.Email)
                    .HasConstraintName("FK_SpotLog_Person");

                entity.HasOne(d => d.MetalRingNavigation)
                    .WithMany(p => p.SpotLogs)
                    .HasForeignKey(d => d.MetalRing)
                    .HasConstraintName("FK_SpotLog_BirdBTO");
            });

            OnModelCreatingPartial(modelBuilder);
        }

        partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
    }
}

这是Program.cs:

using BirdProject.Data;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(connectionString));
builder.Services.AddDatabaseDeveloperPageExceptionFilter();

builder.Services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddEntityFrameworkStores<ApplicationDbContext>();
builder.Services.AddControllersWithViews();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseMigrationsEndPoint();
}
else
{
    app.UseExceptionHandler("/Home/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthentication();
app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");
app.MapRazorPages();

app.Run();

Answer 1

您的 HomeController 需要 BirdProjectContext 但它无法从依赖容器中解析。

要解决此问题，请将您的数据库上下文注册为服务。

在你的`ConfigureServices`方法中

services.AddDbContext<BirdProjectContext>(options => 
{ /* do some configuration with your options*/ 
});

实例化 dbcontext 时出错

An error ocurred instanciating the db context

c#

asp.net

asp.net-mvc

在你的`ConfigureServices`方法中

实例化 dbcontext 时出错

An error ocurred instanciating the db context

c#

asp.net

asp.net-mvc

在你的ConfigureServices方法中

在你的`ConfigureServices`方法中