DbContext不起作用，连接字符串有效

Question

我是MVC和.net核心的新手，所以我不知道如何在我的特定情况下解决这个问题。我觉得telerik的例子过于复杂，但也许我不理解我应该做的事情。

我正试图让Telerik Treelist控件工作：https://demos.telerik.com/aspnet-core/treelist/editing。我的桌子OrgStructures是一个自我参考表与OrgId和ParentId

我想使用一个简单的LINQ命令从我的表OrgStructures中选择数据，但我遇到一个错误，我不知道从哪里开始，但我怀疑dbcontext（ITContext）是不正确的。

有效的是我的应用程序中有其他控制器工作正常，但它的结构与Telerik示例不同。

什么有效：

namespace IT.Web.Controllers
{
    [BreadCrumb(Title = "User Management", UseDefaultRouteUrl = true, Order = 0)]
    public class UserController : BaseController
    {
        public UserController(ITContext dbContext, IConfiguration config) : base(dbContext, config)
        {
        }

        public IActionResult Index()
        {
            UsersViewModel usersVm = new UsersViewModel();
            LoadItemLists(usersVm);

            if (!_sessionUser.IsApplicationAdministrator)
            {
                usersVm.Roles.Remove(usersVm.Roles.Where(o => o.Value == OCWebHelper.Role.ApplicationAdministrator.ToString()).FirstOrDefault());
            }

            return View(usersVm);
        }

         public IActionResult GetAllForGroup([DataSourceRequest] DataSourceRequest request, int groupId)
        {
            var users = _db.GroupUsers
                        .Where(o => o.GroupUserId == groupId)
                        .Include(o => o.User)
                        .OrderBy(o => o.User.LastName).ThenBy(o => o.User.FirstName)
                        .Select(o =>
                          new UserViewModel
                          {
                              Id = o.User.Id,
                              LastName = o.User.LastName,
                              FirstName = o.User.FirstName,
                              Username = o.User.Username,
                              Email = o.User.Email                              
                          });

            return Json(users.ToDataSourceResult(request));
        }

我的appsettings.json：

  "ConnectionStrings": {
    "DefaultConnection": "Data Source=1.11.11.1;Initial Catalog=MyDB;Persist Security Info=True;User ID=MyID;Password=MyPW"
  },

我的行动（什么行不通）：

public virtual IList<OrgStructureModel> GetAll()
{

    using (var db = GetContext())
    {
        var result = Session.GetObjectFromJson<IList<OrgStructureModel>>("OrgStructure");

        if (result == null || UpdateDatabase)
        {
            result = db.OrgStructures
                .ToList()
                .Select(org => org.ToOrgStructureModel(db.OrgStructures.Where(s => s.ParentId == org.OrgId).Count() > 0))
                .ToList();

            Session.SetObjectAsJson("OrgStructure", result);
        }

        return result;
    }
}

错误：

没有为此DbContext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，那么还要确保您的DbContext类型在其构造函数中接受DbContextOptions对象，并将其传递给DbContext的基础构造函数。

我的数据库背景：

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

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

    public virtual ITContext GetContext()
    {
        return new ITContext();
    }

public virtual DbSet<OrgStructure> OrgStructures { get; set; }


    protected override void OnConfiguring(DbContextOptionsBuilder   optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
        }
    }

 protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.HasAnnotation("ProductVersion", "2.2.0-rtm-35687");

        modelBuilder.Entity<GroupUser>(entity =>
        {
            entity.Property(e => e.CreatedDate)
                .HasColumnType("datetime")
                .HasDefaultValueSql("(getdate())");

            entity.HasOne(d => d.GroupUserNavigation)
                .WithMany(p => p.GroupUserGroupUserNavigations)
                .HasForeignKey(d => d.GroupUserId)
                .OnDelete(DeleteBehavior.ClientSetNull)
                .HasConstraintName("FK_GroupUsers_Users1");

            entity.HasOne(d => d.User)
                .WithMany(p => p.GroupUserUsers)
                .HasForeignKey(d => d.UserId)
                .OnDelete(DeleteBehavior.ClientSetNull)
                .HasConstraintName("FK_GroupUsers_Users");
        });

        modelBuilder.Entity<OrgStructure>(entity =>
        {
            entity.ToTable("OrgStructure");

            entity.HasKey(e => e.OrgId);

            entity.Property(e => e.Name)
                .HasColumnType("VARCHAR(50)")
                .HasDefaultValueSql("NULL");

            entity.Property(e => e.Acronym)
                .HasColumnType("VARCHAR(10)")
                .HasDefaultValueSql("NULL");

            entity.Property(e => e.DepartmentCode)
                .HasColumnType("VARCHAR(4)")
                .HasDefaultValueSql("NULL");

            entity.Property(e => e.ParentId)
                .HasColumnType("INT")
                .HasDefaultValueSql("NULL");

            entity.HasOne(d => d.ReportsToNavigation).WithMany(p => p.InverseReportsToNavigation).HasForeignKey(d => d.ParentId);
        });

        OnModelCreatingPartial(modelBuilder);
    }

    partial void OnModelCreatingPartial(ModelBuilder modelBuilder);

我的startup.cs：

services.AddDbContext<ITContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

我的OrgStructureController：

namespace IT.Web.Controllers
{

    public partial class OrgStructureController : Controller
    {

        private IOrgStructureService orgStructure;

        public OrgStructureController(
            IOrgStructureService service)
        {
            orgStructure = service;
        }



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


        public JsonResult All([DataSourceRequest] DataSourceRequest request)
        {
            var result = GetDirectory().ToTreeDataSourceResult(request,
                e => e.OrgId,
                e => e.ParentId,
                e => e
            );

            return Json(result);
        }

        public JsonResult Destroy([DataSourceRequest] DataSourceRequest request, OrgStructureModel org)
        {
            if (ModelState.IsValid)
            {
                orgStructure.Delete(org, ModelState);
            }

            return Json(new[] { org }.ToTreeDataSourceResult(request, ModelState));
        }

        public JsonResult Create([DataSourceRequest] DataSourceRequest request, OrgStructureModel org)
        {
            if (ModelState.IsValid)
            {
                orgStructure.Insert(org, ModelState);
            }

            return Json(new[] { org }.ToTreeDataSourceResult(request, ModelState));
        }

        public JsonResult Update([DataSourceRequest] DataSourceRequest request, OrgStructureModel org)
        {
            if (ModelState.IsValid)
            {
                orgStructure.Update(org, ModelState);
            }

            return Json(new[] { org }.ToTreeDataSourceResult(request, ModelState));
        }

        private IEnumerable<OrgStructureModel> GetDirectory()
        {
            return orgStructure.GetAll();
        }
    }
}

我的OrgStructureService：

namespace IT.Web.Services
{
    using System.Linq;
    using Microsoft.AspNetCore.Mvc.ModelBinding;
    using Microsoft.EntityFrameworkCore;
    using IT.Web.Models;
    using IT.Data.Models;
    using Microsoft.AspNetCore.Http;
    using System.Collections.Generic;

    public static class OrgStructureIEnumerableExtensions
    {
        public static OrgStructureModel ToOrgStructureModel(this OrgStructure org, bool hasChildren)
        {
            return new OrgStructureModel
            {
                OrgId = org.OrgId,
                ParentId = org.ParentId,
                Name = org.Name,
                DepartmentCode = org.DepartmentCode,
                Acronym = org.Acronym,
                hasChildren = hasChildren
            };
        }
    }


    public class OrgStructureService : ITContext, IOrgStructureService
    {
        private static bool UpdateDatabase = false;
        private ISession _session;

        public ISession Session { get { return _session; } }

        public OrgStructureService(IHttpContextAccessor httpContextAccessor)
        {
            _session = httpContextAccessor.HttpContext.Session;
        }

        public virtual IList<OrgStructureModel> GetAll()
        {
            using (var db = GetContext())
            {
                var result = Session.GetObjectFromJson<IList<OrgStructureModel>>("OrgStructure");

                if (result == null || UpdateDatabase)
                {
                    result = db.OrgStructures
                        .ToList()
                        .Select(org => org.ToOrgStructureModel(db.OrgStructures.Where(s => s.ParentId == org.OrgId).Count() > 0))
                        .ToList();

                    Session.SetObjectAsJson("OrgStructure", result);
                }

                return result;
            }
        }


        public virtual void Insert(OrgStructureModel org, ModelStateDictionary modelState)
        {

                if (!UpdateDatabase)
                {
                    var orgs = GetAll();
                    var first = orgs.OrderByDescending(e => e.OrgId).FirstOrDefault();
                    var id = (first != null) ? first.OrgId : 0;

                    org.OrgId = id + 1;

                    orgs.Insert(0, org);

                    Session.SetObjectAsJson("OrgStructure", orgs);
                }
                else
                {
                    using (var db = GetContext())
                    {
                        var entity = org.ToEntity();

                        db.OrgStructures.Add(entity);
                        db.SaveChanges();

                        org.OrgId = entity.OrgId;
                    }
                }

        }

        public virtual void Update(OrgStructureModel org, ModelStateDictionary modelState)
        {
                if (!UpdateDatabase)
                {
                    var orgs = GetAll();
                    var target = orgs.FirstOrDefault(e => e.OrgId == org.OrgId);

                    if (target != null)
                    {
                        target.Name = org.Name;
                        target.Acronym = org.Acronym;
                        target.DepartmentCode = org.DepartmentCode;
                        target.ParentId = org.ParentId;
                    }

                    Session.SetObjectAsJson("OrgStructure", orgs);
                }
                else
                {
                    using (var db = GetContext())
                    {
                        var entity = org.ToEntity();
                        db.OrgStructures.Attach(entity);
                        db.Entry(entity).State = EntityState.Modified;
                        db.SaveChanges();
                    }
                }

        }

        public virtual void Delete(OrgStructureModel org, ModelStateDictionary modelState)
        {
            if (!UpdateDatabase)
            {
                var orgs = GetAll();
                var target = orgs.FirstOrDefault(e => e.OrgId == org.OrgId);

                if (target != null)
                {
                    DeleteSessionChildren(target, orgs);

                    orgs.Remove(target);
                }

                Session.SetObjectAsJson("OrgStructure", orgs);
            }
            else
            {
                using (var db = GetContext())
                {
                    var entity = org.ToEntity();
                    db.OrgStructures.Attach(entity);
                    DeleteEntityChildren(entity);
                    db.SaveChanges();
                }
            }
        }

        private void DeleteEntityChildren(OrgStructure org)
        {
            using (var db = GetContext())
            {
                var children = db.OrgStructures.Where(e => e.ParentId == org.OrgId); 

                foreach (var subordinate in children)
                {
                    DeleteEntityChildren(subordinate);
                }

                db.OrgStructures.Remove(org);
            }
        }

        private void DeleteSessionChildren(OrgStructureModel org, IList<OrgStructureModel> orgs)
        {
            var subordinates = orgs.Where(m => m.ParentId == org.OrgId).ToList();

            foreach (var subordinate in subordinates)
            {
                DeleteSessionChildren(subordinate, orgs);

                orgs.Remove(subordinate);
            }
        }
    }
}

我的看法：

@model IT.Web.Models.OrgStructureModel

@{
    ViewData["Title"] = "Org Structure";
}

@(Html.Kendo().TreeList<IT.Data.Models.OrgStructure>()
    .Name("treelist")
    .Toolbar(toolbar => toolbar.Create())
    .Columns(columns =>
    {
        columns.Add().Field(e => e.Name).Width(220);
        columns.Add().Field(e => e.Acronym).Width(100);
        columns.Add().Field(e => e.DepartmentCode);
        columns.Add().Width(300).Command(c =>
        {
            c.CreateChild().Text("Add child");
            c.Edit();
            c.Destroy();
        })
        .HtmlAttributes(new
        {
            style = "text-align: center;"
        });
    })
    .Editable()
    .Sortable()
    .Filterable()
    .DataSource(dataSource => dataSource
        .Create(create => create.Action("Create", "OrgStructure"))
        .Read(read => read.Action("All", "OrgStructure"))
        .Update(update => update.Action("Update", "OrgStructure"))
        .Destroy(delete => delete.Action("Destroy", "OrgStructure"))
        .Model(m =>
        {
            m.Id(f => f.OrgId);
            m.ParentId(f => f.ParentId);
            m.Expanded(true);
            m.Field(f => f.Name);
            m.Field(f => f.Acronym);
            m.Field(f => f.ParentId);
            m.Field(f => f.DepartmentCode);
        })
    )
    .Height(540)
)

<style>
    .k-treelist .k-command-cell .k-button {
        min-width: 0px;
        padding: 10px 10px 10px 10px;
    }
</style>

我的IOrgStructureService：

namespace IT.Web.Services
{
    public interface IOrgStructureService
    {
        IList<OrgStructureModel> GetAll();
        void Insert(OrgStructureModel org, ModelStateDictionary modelState);
        void Update(OrgStructureModel org, ModelStateDictionary modelState);
        void Delete(OrgStructureModel org, ModelStateDictionary modelState);
    }
}

看起来应用程序中的编码结构与Telerik示例非常不同，因为Telerik有一个额外的服务层，让初学者难以在当前的应用程序结构中工作。我已经跟踪了错误，并且OrgStructure表查询为空。

任何帮助表示赞赏，谢谢！

Answer 1

你的OrgStructureService继承自你的ITContext，但它没有实现任何允许传入DbContextOptionsBuilder的构造函数。因此，无论何时注入此服务，内部数据库连接都没有建立，因此你的错误。

您需要更改构造函数，如：

public class OrgStructureService : ITContext, IOrgStructureService
{
    ...

    public OrgStructureService(DbContextOptionsBuilder builder, IHttpContextAccessor httpContextAccessor)
        : base(builder)
    {
        _session = httpContextAccessor.HttpContext.Session;
    }

然而，这是一个非常糟糕的设计。如果有的话，这个服务应该将上下文作为依赖，而不是从上下文继承：

public class OrgStructureService : IOrgStructureService
{
    private readonly ITContext _context;
    private readonly ISession _session;

    public OrgStructureService(ITContext context, IHttpContextAccessor httpContextAccessor)
    {
        _context = context;
        _session = httpContextAccessor.HttpContext.Session;
    }