C# and Entity Framework Core v7.0.2 code-first – DbContext database provider error during migration Initialization

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英文:

C# and Entity Framework Core v7.0.2 code-first - DbContext database provider error during migration Initialization

问题

我想使用Entity Framework Core 7.0.2和Code First策略初始化我的数据库。

但是当我运行以下命令时：

  1. dotnet ef migrations add InitialCreate --project PreventionCyber.DAL --startup-project PreventionCyber.Web

我遇到了以下错误：

  1. System.InvalidOperationException: 为此DbContext未配置数据库提供程序。可以通过覆盖“DbContext.OnConfiguring”方法或在应用程序服务提供程序上使用“AddDbContext”来配置提供程序。如果使用“AddDbContext”，还请确保您的DbContext类型在其构造函数中接受DbContextOptions<TContext>对象，并将其传递给DbContext的基构造函数。

PCDbContext.cs

  1. using Microsoft.EntityFrameworkCore.ChangeTracking;
  2. using Microsoft.EntityFrameworkCore;
  3. using PreventionCyber.DAL.Common;
  4. using System;
  5. using System.Collections.Generic;
  6. using System.Linq;
  7. using System.Text;
  8. using System.Threading.Tasks;
  10. namespace PreventionCyber.DAL.Context
  11. {
  12.     public class PCDbContext : DbContext
  13.     {
  14.         public PCDbContext()
  15.         {
  16.         }
  18.         public PCDbContext(DbContextOptions<PCDbContext> options): base(options)
  19.         {
  20.         }
  22.         protected override void OnModelCreating(ModelBuilder modelBuilder)
  23.         {
  24.             foreach (var entity in modelBuilder.Model.GetEntityTypes())
  25.             {
  26.                 // Renommage clé primaire
  27.                 entity.GetProperty("Id")
  28.                     ?.SetColumnName($"{entity.ClrType.Name}Id");
  29.             }
  30.         }
  32.         public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
  33.         {
  34.             OnBeforeSaving();
  35.             return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
  36.         }
  38.         private void OnBeforeSaving()   
  39.         {
  40.             var entries = ChangeTracker.Entries();
  42.             foreach (var entry in entries)
  43.             {
  44.                 if (entry.Entity is BaseEntity trackable)
  45.                 {
  46.                     var now = DateTime.UtcNow;
  47.                     var user = GetCurrentUser();
  49.                     switch (entry.State)
  50.                     {
  51.                         case EntityState.Modified:
  52.                             trackable.ModifieLe = now;
  53.                             trackable.ModifiePar = user;
  54.                             break;
  56.                         case EntityState.Added:
  57.                             trackable.CreeLe = now;
  58.                             trackable.CreePar = user;
  59.                             trackable.ModifieLe = now;
  60.                             trackable.ModifiePar = user;
  61.                             break;
  62.                     }
  63.                 }
  64.             }
  65.         }
  67.         private string GetCurrentUser()
  68.         {
  69.             return "UserName"; // TODO implement your own logic
  71.             // If you are using ASP.NET Core, you should look at this answer on StackOverflow
  72.             // https://stackoverflow.com/a/48554738/2996339
  73.         }
  74.     }
  75. }

Program.cs

  1. using Microsoft.EntityFrameworkCore;
  2. using PreventionCyber.DAL.Context;
  3. var builder = WebApplication.CreateBuilder(args);
  5. // 将服务添加到容器中
  6. builder.Services.AddControllersWithViews();
  8. var app = builder.Build();
  10. builder.Services.AddDbContext<DbContext, PCDbContext>(options
  11.     => options.UseSqlServer(builder.Configuration.GetValue<string>("ConnectionStrings:PreventionCyber")));
  13. // 配置HTTP请求管道
  14. if (!app.Environment.IsDevelopment())
  15. {
  16.     app.UseExceptionHandler("/Home/Error");
  17.     // 默认的HSTS值是30天。您可能需要根据生产场景进行更改，参见 https://aka.ms/aspnetcore-hsts。
  18.     app.UseHsts();
  19. }
  21. app.UseHttpsRedirection();
  22. app.UseStaticFiles();
  24. app.UseRouting();
  26. app.UseAuthorization();
  27. app.MapControllerRoute(
  28.     name: "default",
  29.     pattern: "{controller=Home}/{action=Index}/{id?}");
  30. app.Run();

我不理解这个错误，因为我已经使用DbContextOptions<PCDbContext>定义了构造函数，并且我还在Program.cs中将DbContext添加到builder.Services中。

有人能找到错误吗？谢谢！

英文:

I want to initialize my database with Entity Framework Core 7.0.2 using a code-first strategy.

But when I launch this command:

  1. dotnet ef migrations add InitialCreate --project PreventionCyber.DAL --startup-project PreventionCyber.Web

I get this error :

> System.InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the 'DbContext.OnConfiguring' method or by using 'AddDbContext' on the application service provider. If 'AddDbContext' is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.

PCDbContext.cs

  1. using Microsoft.EntityFrameworkCore.ChangeTracking;
  2. using Microsoft.EntityFrameworkCore;
  3. using PreventionCyber.DAL.Common;
  4. using System;
  5. using System.Collections.Generic;
  6. using System.Linq;
  7. using System.Text;
  8. using System.Threading.Tasks;
  10. namespace PreventionCyber.DAL.Context
  11. {
  12.     public class PCDbContext : DbContext
  13.     {
  14.         public PCDbContext()
  15.         {
  16.         }
  18.         public PCDbContext(DbContextOptions&lt;PCDbContext&gt; options): base(options)
  19.         {
  20.         }
  22.         protected override void OnModelCreating(ModelBuilder modelBuilder)
  23.         {
  24.             foreach (var entity in modelBuilder.Model.GetEntityTypes())
  25.             {
  26.                 // Renommage cl&#233; primaire
  27.                 entity.GetProperty(&quot;Id&quot;)
  28.                     ?.SetColumnName($&quot;{entity.ClrType.Name}Id&quot;);
  29.             }
  30.         }
  32.         public override Task&lt;int&gt; SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
  33.         {
  34.             OnBeforeSaving();
  35.             return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
  36.         }
  38.         private void OnBeforeSaving()   
  39.         {
  40.             var entries = ChangeTracker.Entries();
  42.             foreach (var entry in entries)
  43.             {
  44.                 if (entry.Entity is BaseEntity trackable)
  45.                 {
  46.                     var now = DateTime.UtcNow;
  47.                     var user = GetCurrentUser();
  49.                     switch (entry.State)
  50.                     {
  51.                         case EntityState.Modified:
  52.                             trackable.ModifieLe = now;
  53.                             trackable.ModifiePar = user;
  54.                             break;
  56.                         case EntityState.Added:
  57.                             trackable.CreeLe = now;
  58.                             trackable.CreePar = user;
  59.                             trackable.ModifieLe = now;
  60.                             trackable.ModifiePar = user;
  61.                             break;
  62.                     }
  63.                 }
  64.             }
  65.         }
  67.         private string GetCurrentUser()
  68.         {
  69.             return &quot;UserName&quot;; // TODO implement your own logic
  71.             // If you are using ASP.NET Core, you should look at this answer on StackOverflow
  72.             // https://stackoverflow.com/a/48554738/2996339
  73.         }
  74.     }
  75. }

Program.cs

  1. using Microsoft.EntityFrameworkCore;
  2. using PreventionCyber.DAL.Context;
  3. var builder = WebApplication.CreateBuilder(args);
  5. // AddAsync services to the container.
  6. builder.Services.AddControllersWithViews();
  8. var app = builder.Build();
  10. builder.Services.AddDbContext&lt;DbContext, PCDbContext&gt;(options
  11.     =&gt; options.UseSqlServer(builder.Configuration.GetValue&lt;string&gt;(&quot;ConnectionStrings:PreventionCyber&quot;)));
  13. // Configure the HTTP request pipeline.
  14. if (!app.Environment.IsDevelopment())
  15. {
  16.     app.UseExceptionHandler(&quot;/Home/Error&quot;);
  17.     // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
  18.     app.UseHsts();
  19. }
  21. app.UseHttpsRedirection();
  22. app.UseStaticFiles();
  24. app.UseRouting();
  26. app.UseAuthorization();
  27. app.MapControllerRoute(
  28.     name: &quot;default&quot;,
  29.     pattern: &quot;{controller=Home}/{action=Index}/{id?}&quot;);
  30. app.Run();

I don't understand the error because I've already defined a constructor using DbContextOptions&lt;TContext&gt; and I added the DbContext to the builder.Services too in Program.cs.

Can anyone find the error? Thanks!

答案1

得分: 0

The error suggested you may need to add the OnConfiguring override method to the PCDbContext class.

  1. protected override void OnConfiguring(DbContextOptionsBuilder options)
  2. {
  3.     options.UseSqlServer(&lt;yourConnectionString&gt;);
  4. }
英文:

The error suggested you may need to add the OnConfiguring override method to the PCDbContext class.

  1.         protected override void OnConfiguring(DbContextOptionsBuilder options)
  2.         {
  3.             options.UseSqlServer(&lt;yourConnectionString&gt;);
  4.         }
  5.     ```
  7. </details>

huangapple
  • 本文由 发表于 2023年2月14日 04:03:42
  • 转载请务必保留本文链接：https://go.coder-hub.com/75440675.html
  • asp.net-mvc
  • c#
  • entity-framework-core
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