[英]LINQPad EF Core no database provider has been configured for this DbContext
[英]EF Core 3.1.8 - Migrations Error - No database provider has been configured for this DbContext
我正在嘗試添加遷移並收到以下錯誤:
Build started...
Build succeeded.
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.
at Microsoft.EntityFrameworkCore.Internal.DbContextServices.Initialize(IServiceProvider scopedProvider, IDbContextOptions contextOptions, DbContext context)
at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
at Microsoft.EntityFrameworkCore.DbContext.Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.get_Instance()
at Microsoft.EntityFrameworkCore.Infrastructure.Internal.InfrastructureExtensions.GetService[TService](IInfrastructure`1 accessor)
at Microsoft.EntityFrameworkCore.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure`1 accessor)
at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory)
at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
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.
已經嘗試添加EntityFrameworkCore.Design package 並且我的構造函數就像
public MyContext(DbContextOptions<MyContext> options) : base(options)
{
}
並繼續拋出錯誤:
無法創建“MyContext”類型的 object。 有關設計時支持的不同模式,請參閱https://go.microsoft.com/fwlink/?linkid=851728
更新了數據庫配置
觀察:
public class MyContext : DbContext
{
public VenturaContext(DbContextOptions<MyContext> options) : base(options)
{
}
public DbSet<Usuario> Usuarios { get; set; }
public DbSet<Employee> Employees { get; set; }
public DbSet<Admin> Administrators { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
//modelBuilder.Entity<User>().ToTable("Users");
base.OnModelCreating(modelBuilder);
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
base.OnConfiguring(optionsBuilder);
}
}
[更新 2 - 我的簡單解決方案]
只需在 OnConfiguring 方法上設置我的連接字符串,並在 MyContext 上創建一個空的構造函數。 這對於正在創造的東西來說已經足夠了。
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
if (!optionsBuilder.IsConfigured)
{
optionsBuilder.UseSqlServer("Server=KONOHA; Database=my_database; User Id=user; password=********; MultipleActiveResultSets=true");
}
base.OnConfiguring(optionsBuilder);
}
你可以看看這篇文章。
通過 AddDbContext 配置 DBContext:
services.AddDbContext<MyContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
然后在你的 MyContext 中:
public class MyContext : DbContext
{
public MyContext(DbContextOptions<MyContext> options) : base(options)
{
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
}
}
應用設置.json:
"ConnectionStrings": {
"DefaultConnection": "Server=(localdb)\\mssqllocaldb;Database=MyContext;Trusted_Connection=True;MultipleActiveResultSets=true"
}
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