在Blazor服務器中使用資料庫背景關系工廠-有解無憂

我在為我的服務器端 Blazor 應用程式設定 EF 資料庫連接時遇到了一些問題。它一直在使用標準DbContext設定，直到我注意到由于 Blazor 的性質而導致連接無法正確關閉的一些問題，始終使用相同的背景關系。我的研究讓我看了一下DbContextFactory，但IDbContextFactory現在不推薦使用該界面而支持IDesignTimeDbContextFactory.

我已經建立了一個類來實作介面：

public class FIS2ContextFactory : IDesignTimeDbContextFactory<FIS2_DbContext>
{
    private readonly DbContextOptions<FIS2_FranklinContext_AutoGenerated> options;

    public FIS2ContextFactory(DbContextOptions<FIS2_FranklinContext_AutoGenerated> contextOptions)
    {
        options = contextOptions;
    }

    public FIS2_DbContext CreateDbContext(string[] args)
    {
        return new FIS2_DbContext(options);
    }
}

我要使用的 DbContext 是這樣的，它繼承并擴展了 EF Power Tools 生成的 DbContext：

public partial class FIS2_DbContext : FIS2_FranklinContext_AutoGenerated
{
    public FIS2_DbContext()
    {
    }

    public FIS2_DbContext(DbContextOptions<FIS2_FranklinContext_AutoGenerated> options) : base(options)

    {
    }

    public virtual DbSet<StudentBasicDetailsWithCurrentTg> StudentBasicDetailsWithCurrentTgs { get; set; }
    public virtual DbSet<CurriculumSearchBasicDetails> CurriculumSearchBasicDetails { get; set; }
    public virtual DbSet<StudentAllEnrolments> StudentAllEnrolments { get; set; }
}

在我的方法中，startup.cs我將它設定為這樣ConfigureServices：

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContextFactory<FIS2_DbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("FIS2")));

        services.AddRazorPages();
        services.AddServerSideBlazor();
        services.AddScoped<IFileService, FileService>();
        services.AddScoped<IEmailService, EmailService>();
        services.AddScoped<ITimetableService, TimetableService>();
        services.AddScoped<ICurriculumService, CurriculumServiceEf>();
        services.AddScoped<IStudentService, StudentServiceEf>();
        services.AddScoped<ICollectionService, CollectionsServiceEf>();
        services.AddHttpContextAccessor();
        services.AddHttpClient();
        services.AddAuthenticationCore();
        services.AddAuthentication(IISDefaults.AuthenticationScheme);
        services.AddAuthorization();
        services.AddSyncfusionBlazor();
        services.AddScoped<SessionState>();
    }

我的問題是，當它開始設定使用此資料庫連接的服務時，我在以下位置遇到此錯誤訊息program.cs：

無法構建某些服務（驗證服務描述符時出錯：“ServiceType: DataLibrary.Data.Interfaces.ITimetableService Lifetime: Scoped ImplementationType: DataLibrary.Data.BusinessLayer.TimetableService”：無法決議“DataLibrary.Models”型別的服務。 FIS2ContextFactory 試圖激活“DataLibrary.Data.BusinessLayer.TimetableService”。）（驗證服務描述符“ServiceType: DataLibrary.Data.Interfaces.ICurriculumService Lifetime: Scoped ImplementationType: DataLibrary.Data.BusinessLayer.CurriculumServiceEf”時出錯：無法嘗試激活“DataLibrary.Data.BusinessLayer.CurriculumServiceEf”時決議型別“DataLibrary.Models.FIS2ContextFactory”的服務。（驗證服務描述符時出錯）ServiceType：DataLibrary.Data.Interfaces.IStudentService Lifetime：Scoped ImplementationType：DataLibrary.Data.BusinessLayer.StudentServiceEf'：嘗試激活'DataLibrary.Data.BusinessLayer.StudentServiceEf'時無法決議型別'DataLibrary.Models.FIS2ContextFactory'的服務。 )（驗證服務描述符“ServiceType: DataLibrary.Data.Interfaces.ICollectionService Lifetime: Scoped ImplementationType: DataLibrary.Data.BusinessLayer.CollectionsServiceEf”時出錯：嘗試激活“DataLibrary.Models.FIS2ContextFactory”時無法決議“DataLibrary.Models.FIS2ContextFactory”型別的服務DataLibrary.Data.BusinessLayer.CollectionsServiceEf'.)嘗試激活“DataLibrary.Data.BusinessLayer.StudentServiceEf”時無法決議“DataLibrary.Models.FIS2ContextFactory”型別的服務。（驗證服務描述符“ServiceType: DataLibrary.Data.Interfaces.ICollectionService Lifetime: Scoped ImplementationType”時出錯： DataLibrary.Data.BusinessLayer.CollectionsServiceEf”：嘗試激活“DataLibrary.Data.BusinessLayer.CollectionsServiceEf”時無法決議“DataLibrary.Models.FIS2ContextFactory”型別的服務。）嘗試激活“DataLibrary.Data.BusinessLayer.StudentServiceEf”時無法決議“DataLibrary.Models.FIS2ContextFactory”型別的服務。（驗證服務描述符“ServiceType: DataLibrary.Data.Interfaces.ICollectionService Lifetime: Scoped ImplementationType”時出錯： DataLibrary.Data.BusinessLayer.CollectionsServiceEf”：嘗試激活“DataLibrary.Data.BusinessLayer.CollectionsServiceEf”時無法決議“DataLibrary.Models.FIS2ContextFactory”型別的服務。）DataLibrary.Data.BusinessLayer.CollectionsServiceEf”：嘗試激活“DataLibrary.Data.BusinessLayer.CollectionsServiceEf”時無法決議“DataLibrary.Models.FIS2ContextFactory”型別的服務。）DataLibrary.Data.BusinessLayer.CollectionsServiceEf”：嘗試激活“DataLibrary.Data.BusinessLayer.CollectionsServiceEf”時無法決議“DataLibrary.Models.FIS2ContextFactory”型別的服務。）

作為參考，這里是如何TimetableService設定的示例（其他以相同方式實體化）：

using DataLibrary.Data.Interfaces;
using DataLibrary.Models;
using DataLibrary.Models.timetable;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace DataLibrary.Data.BusinessLayer
{
    public class TimetableService : ITimetableService
    {
        private FIS2ContextFactory _contextFactory;

        public TimetableService(FIS2ContextFactory db)
        {
            _contextFactory = db;
        }

        public async Task<List<spGetHolidaysBetweenDatesResult>> GetHolidaysBetweenDatesAsync(DateTime startDate, DateTime endDate)
        {
            string[] args = { "" };
            var _db = _contextFactory.CreateDbContext(args);
            var procedures = _db.Procedures;

            return await procedures.spGetHolidaysBetweenDatesAsync(startDate, endDate);
        }

        public async Task<List<PeriodsBetweenDates>> GetPeriodsBetweenDatesAsync(DateTime startDate, DateTime endDate)
        {
            string[] args = { "" };
            var _db = _contextFactory.CreateDbContext(args);
            var procedures = _db.Procedures;
            var toReturn = new List<PeriodsBetweenDates>();
            var results = await procedures.spGetPeriodsBetweenDatesAsync(startDate, endDate);
            foreach (var item in results)
            {
                toReturn.Add(new PeriodsBetweenDates(item.Date, item.Timetable, item.BlockCode, item.StartTime, item.EndTime));
            }
            return toReturn;
        }

        public async Task<List<StudentTimetable>> GetStudentTimetableAsync(DateTime startDate, DateTime endDate, string studentID)
        {
            string[] args = { "" };
            var _db = _contextFactory.CreateDbContext(args);
            var procedures = _db.Procedures;
            var results = await procedures.spGetStudentTimetableAsync(startDate, endDate, studentID);

            List<StudentTimetable> studentTimetables = new List<StudentTimetable>();
            foreach (var item in results)
            {
                studentTimetables.Add(JsonConvert.DeserializeObject<StudentTimetable>(item.timetable));
            }
            return studentTimetables;
        }
    }
}

是因為我在啟動時使用了錯誤的方法來創建背景關系工廠，還是后來我出錯了？

uj5u.com熱心網友回復：

如果要決議特定的工廠型別，則必須注冊此多載，AddDbContextFactory<TContext,TFactory>記錄在此處：

此多載允許注冊 IDbContextFactory 的特定實作，而不是使用 EF Core 附帶的默認工廠。

所以

services.AddDbContextFactory<FIS2_DbContext,FIS2ContextFactory>(options => options.UseSqlServer(Configuration.GetConnectionString("FIS2")));

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