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很抱歉这个基本问题。

我目前正在研究使用 Blazor Server 进行应用程序开发，但无法连接到数据库。

我正在尝试使用 DI 连接到数据库。我创建了一个使用工厂模式的代码，如下所示，但是在获取连接字符串的部分出现错误。

    public void ConfigureServices(IServiceCollection services)
    {
        //error:CS0121  Inappropriate call between the following methods or properties: 'Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.AddDbContextFactory<TContext>(Microsoft.Extensions.DependencyInjection.IServiceCollection, System.Action<Microsoft.EntityFrameworkCore.DbContextOptionsBuilder>, Microsoft.Extensions.DependencyInjection.ServiceLifetime)' と 'BlazorSv.Models.FactoryExtensions.AddDbContextFactory<TContext>(Microsoft.Extensions.DependencyInjection.IServiceCollection, System.Action<Microsoft.EntityFrameworkCore.DbContextOptionsBuilder>, Microsoft.Extensions.DependencyInjection.ServiceLifetime)'

        services.AddDbContextFactory<BlazorSv.Models.SQLbeginnerContext>(options => options.UseNpgsql(Configuration.GetConnectionString("DBConnection")));
        services.AddRazorPages();
        services.AddServerSideBlazor();
        services.AddSingleton<WeatherForecastService>();
    }

我以为 <Models.SQLbeginnerContext> 部分的定义有歧义，所以我写了层次结构，但它不起作用。

我该怎么办这个错误？我想要一些建议

下面是描述 StartUp.cs 和工厂模式的 SQLbegginerContext.cs。

启动.cs

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

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
    public void ConfigureServices(IServiceCollection services)
    {
        //error:CS0121  Inappropriate call between the following methods or properties: 'Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.AddDbContextFactory<TContext>(Microsoft.Extensions.DependencyInjection.IServiceCollection, System.Action<Microsoft.EntityFrameworkCore.DbContextOptionsBuilder>, Microsoft.Extensions.DependencyInjection.ServiceLifetime)' と 'BlazorSv.Models.FactoryExtensions.AddDbContextFactory<TContext>(Microsoft.Extensions.DependencyInjection.IServiceCollection, System.Action<Microsoft.EntityFrameworkCore.DbContextOptionsBuilder>, Microsoft.Extensions.DependencyInjection.ServiceLifetime)'

        services.AddDbContextFactory<Models.SQLbeginnerContext>(options => options.UseNpgsql(Configuration.GetConnectionString("DBConnection")));
        services.AddRazorPages();
        services.AddServerSideBlazor();
        services.AddSingleton<WeatherForecastService>();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/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.UseEndpoints(endpoints =>
        {
            endpoints.MapBlazorHub();
            endpoints.MapFallbackToPage("/_Host");
        });
    }
}

SQLbeginerContext.cs

public interface IDbContextFactory<TContext> where TContext : DbContext
{
    TContext CreateDbContext();
}

public class blazordbFactory<TContext> : IDbContextFactory<TContext> where TContext : DbContext
{
    public blazordbFactory(IServiceProvider provider)
    {
        this.provider = provider;
    }
    private readonly IServiceProvider provider;
    public TContext CreateDbContext()
    {
        return ActivatorUtilities.CreateInstance<TContext>(provider);
    }
}

public static class FactoryExtensions
{
    public static IServiceCollection AddDbContextFactory<TContext>(
        this IServiceCollection collection,
        Action<DbContextOptionsBuilder> optionsAction = null,
        ServiceLifetime contextAndOptionsLifetime = ServiceLifetime.Singleton)
        where TContext : DbContext
    {
        collection.Add(new ServiceDescriptor(
            typeof(IDbContextFactory<TContext>),
            sp => new blazordbFactory<TContext>(sp),
            contextAndOptionsLifetime));
        collection.Add(new ServiceDescriptor(
            typeof(DbContextOptions<TContext>),
            sp => GetOptions<TContext>(optionsAction, sp),
            contextAndOptionsLifetime));

        return collection;
    }
    private static DbContextOptions<TContext> GetOptions<TContext>(
        Action<DbContextOptionsBuilder> action,
        IServiceProvider sp = null) where TContext : DbContext
    {
        var optionsBuilder = new DbContextOptionsBuilder<TContext>();
        if (sp != null)
        {
            optionsBuilder.UseApplicationServiceProvider(sp);
        }
        action?.Invoke(optionsBuilder);
        return optionsBuilder.Options;
    }
}


public partial class SQLbeginnerContext : DbContext
{
    public SQLbeginnerContext()
    {
    }

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

附记：SQLbeginer.cs

//Comment out this part
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder){
 if (!optionsBuilder.IsConfigured)
    {
      optionsBuilder.UseNpgsql("Host=localhost; Database=SQLbeginner; Username=user; Password=****")
    }
}
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