MVC 与 EF 关系数据库映射

Question

当我尝试更新我的数据库以填充我的表时出现此错误。

PM> 更新数据库

No pending explicit migrations.
Running Seed method.
System.InvalidOperationException: Sequence contains no matching element
   at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate)
   at RecreationServicesTicketingSystem.Migrations.Configuration.Seed(IssueContext context) in C:\Users\jwan\Documents\Visual Studio 2012\Projects\RecreationServicesTicketingSystem\RecreationServicesTicketingSystem\Migrations\Configuration.cs:line 60
   at System.Data.Entity.Migrations.DbMigrationsConfiguration`1.OnSeed(DbContext context)
   at System.Data.Entity.Migrations.DbMigrator.SeedDatabase()
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.SeedDatabase()
   at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
   at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.<Update>b__b()
   at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
   at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
   at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.Run()
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
   at System.Data.Entity.Migrations.Design.ToolingFacade.Update(String targetMigration, Boolean force)
   at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
   at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
Sequence contains no matching element

我一直在谷歌搜索，似乎没有人遇到过类似的问题。在这条线上 var administrator = new List<Administrator> 我放入了一个指针，指出第 60 行在哪里。

Click Here Tables from SQL Server Management Studio

Click Here for Entity Models

 public Configuration()
        {
            AutomaticMigrationsEnabled = false;
        }
    protected override void Seed(RecreationalServicesTicketingSystem.DAL.IssueContext context)
    {

        var departments = new List<Department>
        {
            new Department { DepartmentID = 1, Name = "IT"},
            new Department { DepartmentID = 2, Name = "Admin" },
            new Department { DepartmentID = 3, Name = "Human Resources"},
            new Department { DepartmentID = 4, Name = "Mechanics" },
            new Department { DepartmentID = 5, Name = "Directors" },
            new Department { DepartmentID = 6, Name = "Operations"}

        };
        departments.ForEach(s => context.Departments.AddOrUpdate(p => p.Name, s));
        context.SaveChanges();


        var depots = new List<Depot>
        {
            new Depot { DepotID = 1, Name = "Porana"},
            new Depot { DepotID = 2, Name = "Far North"},


        };
        departments.ForEach(s => context.Departments.AddOrUpdate(p => p.Name, s));
        context.SaveChanges();

    var users = new List<User>
{
    new User { FirstMidName = "Jason",   LastName = "Wan",
        EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentID = 1, DepotID = 1},
    new User { FirstMidName = "Andy", LastName = "Domagas",
        EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentID = 1,DepotID = 1},
    new User { FirstMidName = "Denis",   LastName = "Djohar",
        EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentID = 1 ,DepotID = 1},
    new User { FirstMidName = "Christine",   LastName = "West",
        EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentID = 1, DepotID = 1},

};

        var administrator = new List<Administrator> <-- LINE 60
        {
            new Administrator {AdminID = 1, AdminRole = "Administrator LVL1", User = users.Single ( s => s.UserID == 1),
            Tickets = new List<Ticket>() },
            new Administrator {AdminID = 2, AdminRole = "Administrator LVL2", User = users.Single ( s => s.UserID == 2),
            Tickets = new List<Ticket>() },
            new Administrator {AdminID = 3, AdminRole = "Administrator LVL3", User = users.Single ( s => s.UserID == 3),
            Tickets = new List<Ticket>() }

        };
        administrator.ForEach(s => context.Administrators.AddOrUpdate(p => p.AdminID, s));
        context.SaveChanges();

        var categories = new List<Category>
        {
            new Category {CategoryID = 0001, Title = "Desktop"},
            new Category {CategoryID = 0002, Title = "Mobile"},
            new Category {CategoryID = 0003, Title = "Menzits"},
            new Category {CategoryID = 0004, Title = "XMPRO"},
            new Category {CategoryID = 0005, Title = "Con-X"},
            new Category {CategoryID = 0006, Title = "Promapp"},
            new Category {CategoryID = 0007, Title = "QGIS"},
        };
        categories.ForEach(s => context.Categories.AddOrUpdate(p => p.Title, s));
        context.SaveChanges();

        var tickets = new List<Ticket>
        {
            new Ticket {
                UserID = users.Single(s => s.LastName == "Wan").UserID,
                CategoryID = categories.Single(c => c.Title == "Con-X" ).CategoryID,
                Issue = ("Test Error 1"),
                Priority = Priority.High
            },
            new Ticket {
                UserID = users.Single(s => s.LastName == "Wan").UserID,
                CategoryID = categories.Single(c => c.Title == "Desktop" ).CategoryID,
                Issue = ("Test Error 2"),
                Priority = Priority.Med
            },
        };


        foreach (Ticket e in tickets)
        {
            var ticketInDataBase = context.Tickets.Where(
                s =>
                    s.User.UserID == e.UserID &&
                    s.Category.CategoryID == e.CategoryID).SingleOrDefault();
            if (ticketInDataBase == null)
            {
                context.Tickets.Add(e);
            }
        }
        context.SaveChanges();

    }
}

User.cs

public class User
    {

        public int UserID { get; set; }
        [StringLength(50, MinimumLength = 1)]
        public string LastName { get; set; }
        [StringLength(50, MinimumLength = 1, ErrorMessage = "First name cannot be longer than 50 characters.")]

        [Column("FirstName")]
        public string FirstMidName { get; set; }

        [DataType(DataType.Date)]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
        public DateTime EnrollmentDate { get; set; }

        public string FullName
        {
            get { return LastName + ", " + FirstMidName; }
        }
        public int AdministratorID { get; set; }
        [ForeignKey("AdministratorID")]
        public virtual Administrator Administrator { get; set; }

        public int DepartmentID { get; set; }
        [ForeignKey("DepartmentID")]
        public virtual Department Department { get; set; }


        public int DepotID { get; set; }
        [ForeignKey("DepotID")]
        public virtual Depot Depot { get; set; }

        public int TicketID { get; set; }

        public virtual ICollection<Ticket> Users { get; set; }

    }

Department.cs

public class Department
{

    public int DepartmentID { get; set; }

    [StringLength(50, MinimumLength = 1)]
    public string Name { get; set; }

    public virtual ICollection<User> Users { get; set; }
}

Depot.cs

public class Depot
{

    public int DepotID { get; set; }
    [StringLength(50, MinimumLength = 1)]
    public string Name { get; set; }
    public virtual ICollection<User> Users { get; set; }

}

Answer 1

当您创建用户时，您没有指定他们所属的部门，这意味着对于 int 字段，默认情况下它将为 0。您的数据库中没有 ID 为 0 的部门，因此外键约束被侵犯。尝试类似的东西：

var users = new List<User>
        {
            new User { FirstMidName = "Jason",   LastName = "Wan",
                EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentId = 1 },
            new User { FirstMidName = "Andy", LastName = "Domagas",
                EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentId = 1 },
            new User { FirstMidName = "Denis",   LastName = "Djohar",
                EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentId = 1 },
            new User { FirstMidName = "Christine",   LastName = "West",
                EnrollmentDate = DateTime.Parse("2016-02-18"), DepartmentId = 1 },

        };

解决仓库问题的更新：

您正在创建 depot，但是将它们添加到上下文的行引用的是部门而不是 depot：

 var depots = new List<Depot>
        {
            new Depot { DepotID = 1, Name = "Porana"},
            new Depot { DepotID = 2, Name = "Far North"},


        };
        departments.ForEach(s => context.Departments.AddOrUpdate(p => p.Name, s));// should be:
        depots.ForEach(s => context.Depots.AddOrUpdate(p => p.Name, s));
        context.SaveChanges();

MVC 与 EF 关系数据库映射

MVC with EF Relational Database Mapping

c#

asp.net-mvc

entity-framework

relational-database