我遇到了一个问题，即EF Core不允许我添加第二次迁移。 我有以下DataContext设置：
public class DataContext : IdentityDbContext<User, Role, Guid, IdentityUserClaim<Guid>, UserRole, IdentityUserLogin<Guid>, IdentityRoleClaim<Guid>, IdentityUserToken<Guid>>
{
public DataContext(DbContextOptions<DataContext> options)
: base(options)
{
}
/* Global */
public virtual DbSet<Audit> Audits { get; set; }
public virtual DbSet<AuditType> AuditType { get; set; }
/* Portal */
public virtual DbSet<RefreshToken> RefreshTokens { get; set; }
public virtual DbSet<Product> Products { get; set; }
public virtual DbSet<Group> Groups { get; set; }
public virtual DbSet<GroupType> GroupTypes { get; set; }
public virtual DbSet<GroupProperty> GroupProperties { get; set; }
/* SVault */
public virtual DbSet<LicensePropertyType> LicensePropertyTypes { get; set; }
public virtual DbSet<LicenseProduct> LicenseProducts { get; set; }
public virtual DbSet<LicenseState> LicenseStates { get; set; }
public virtual DbSet<LicenseType> LicenseTypes { get; set; }
public virtual DbSet<LicenseStatus> LicenseStatus { get; set; }
public virtual DbSet<BackupState> BackupStates { get; set; }
public virtual DbSet<BackupMode> BackupModes { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
IList<AuditType> audittypes = new List<AuditType>()
{
new AuditType() { Id = 1, Name = "USER_CREATE" },
new AuditType() { Id = 2, Name = "USER_UPDATE" },
new AuditType() { Id = 3, Name = "USER_DELETE" },
new AuditType() { Id = 4, Name = "USER_RESET_PASSWORD" },
new AuditType() { Id = 5, Name = "USER_2FA_GENERATE" },
new AuditType() { Id = 6, Name = "USER_TOKEN_GENERATE" },
new AuditType() { Id = 7, Name = "USER_REQUEST_RESET_PASSWORD" },
new AuditType() { Id = 20, Name = "ROLE_ADD" },
new AuditType() { Id = 21, Name = "ROLE_DELETE" },
new AuditType() { Id = 30, Name = "GROUP_CREATE" },
new AuditType() { Id = 31, Name = "GROUP_UPDATE" },
new AuditType() { Id = 32, Name = "GROUP_DELETE" },
new AuditType() { Id = 35, Name = "GROUP_PROPERTY_ADD" },
new AuditType() { Id = 36, Name = "GROUP_PROPERTY_DELETE" },
new AuditType() { Id = 50, Name = "SVAULT_LICENSE_CREATE", ProductId = 1 },
new AuditType() { Id = 51, Name = "SVAULT_LICENSE_UPDATE", ProductId = 1 },
new AuditType() { Id = 52, Name = "SVAULT_LICENSE_DELETE", ProductId = 1 },
new AuditType() { Id = 53, Name = "SVAULT_LICENSE_VALIDATE_TRIAL", ProductId = 1 },
new AuditType() { Id = 54, Name = "SVAULT_LICENSE_MIGRATE", ProductId = 1 },
new AuditType() { Id = 55, Name = "SVAULT_LICENSE_PROPERTIES_UPDATE", ProductId = 1 },
new AuditType() { Id = 70, Name = "SVAULT_DATASET_CREATE", ProductId = 1 },
new AuditType() { Id = 71, Name = "SVAULT_DATASET_UPDATE", ProductId = 1 },
new AuditType() { Id = 72, Name = "SVAULT_DATASET_DELETE", ProductId = 1 },
new AuditType() { Id = 73, Name = "SVAULT_DATASET_RESTORE", ProductId = 1 },
new AuditType() { Id = 74, Name = "SVAULT_DATASET_BACKUP", ProductId = 1 },
new AuditType() { Id = 80, Name = "SVAULT_DATASET_SCHED_CREATE", ProductId = 1 },
new AuditType() { Id = 81, Name = "SVAULT_DATASET_SCHED_UPDATE", ProductId = 1 },
new AuditType() { Id = 82, Name = "SVAULT_DATASET_SCHED_DELETE", ProductId = 1 },
};
Guid mProvider = Guid.NewGuid();
IList<User> users = new List<User>()
{
new User() { Id = Guid.NewGuid(), UserName = "*****************", NormalizedUserName = "*****************".ToUpper(), Email = "*****************", NormalizedEmail = "*****************".ToUpper(), EmailConfirmed = true, PasswordHash = "*****************", SecurityStamp = "*****************", ConcurrencyStamp = "*****************", PhoneNumber = null, PhoneNumberConfirmed = false, TwoFactorEnabled = false, LockoutEnd = null, LockoutEnabled = true, AccessFailedCount = 0, FirstName = "*****************", LastName = "*****************", IsAdmin = true, GroupId = mProvider },
new User() { Id = Guid.NewGuid(), UserName = "*****************", NormalizedUserName = "*****************".ToUpper(), Email = "*****************", NormalizedEmail = "*****************".ToUpper(), EmailConfirmed = true, PasswordHash = "*****************", SecurityStamp = "*****************", ConcurrencyStamp = "*****************", PhoneNumber = null, PhoneNumberConfirmed = false, TwoFactorEnabled = false, LockoutEnd = null, LockoutEnabled = true, AccessFailedCount = 0, FirstName = "*****************", LastName = "*****************", IsAdmin = true, GroupId = mProvider }
};
IList<Product> products = new List<Product>()
{
new Product(){ Id = 1 ,LongName = "AGS Backup SVault", Description = String.Empty, ShortName = "SVault", RouteUrl = "/svault/dashboard", IconUrl = "assets/images/picto/picto_backup.svg", ThemeColor = "ags-500", Enabled = true },
new Product(){ Id = 2 ,LongName = "AGS Hosting", Description = String.Empty, ShortName = "Hosting", RouteUrl = "/hosting/dashboard", IconUrl = "assets/images/picto/picto_hosting.svg", ThemeColor = "ags-600", Enabled = false },
new Product(){ Id = 3 ,LongName = "AGS VEEAM Cloud Connect", Description = String.Empty, ShortName = "VEEAM", RouteUrl = "/veeam/dashboard", IconUrl = "assets/images/picto/picto_veeam.svg", ThemeColor = "ags-300", Enabled = false },
new Product(){ Id = 4 ,LongName = "AGS Mail Zimbra", Description = String.Empty, ShortName = "Zimbra", RouteUrl = "/mail/dashboard", IconUrl = "assets/images/picto/picto_messagerie.svg", ThemeColor = "ags-700", Enabled = false },
new Product(){ Id = 5 ,LongName = "AGS Mail Exchange", Description = String.Empty, ShortName = "Exchange", RouteUrl = "/mail/dashboard", IconUrl = "assets/images/picto/picto_messagerie.svg", ThemeColor = "ags-700", Enabled = false },
new Product(){ Id = 6 ,LongName = "AGS Office365", Description = String.Empty, ShortName = "Office365", RouteUrl = "/office365/dashboard", IconUrl = "assets/images/picto/picto_office.svg", ThemeColor = "ags-800", Enabled = false },
new Product(){ Id = 7 ,LongName = "AGS MailProtect", Description = String.Empty, ShortName = "MailProtect", RouteUrl = "/mailprotect/dashboard", IconUrl = "assets/images/picto/picto_protect.svg", ThemeColor = "ags-900", Enabled = false },
new Product(){ Id = 8 ,LongName = "AGS MailInBlack", Description = String.Empty, ShortName = "MailInBlack", RouteUrl = "/mailinblack/dashboard", IconUrl = "assets/images/picto/picto_protect.svg", ThemeColor = "ags-900", Enabled = false },
new Product(){ Id = 9 ,LongName = "AGS MonCloud", Description = String.Empty, ShortName = "MonCloud", RouteUrl = "/moncloud/dashboard", IconUrl = "assets/images/picto/picto_moncloud.svg", ThemeColor = "ags-400", Enabled = false }
};
IList<Role> roles = new List<Role>()
{
/* SVault Roles */
new Role() { Id = Guid.NewGuid(), ProductId = 1, Name = RolesHelper.SvaultRoles.RoleAdmin, NormalizedName = RolesHelper.SvaultRoles.RoleAdmin.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 1, Name = RolesHelper.SvaultRoles.RoleBackup, NormalizedName = RolesHelper.SvaultRoles.RoleBackup.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 1, Name = RolesHelper.SvaultRoles.RoleRestore, NormalizedName = RolesHelper.SvaultRoles.RoleRestore.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 1, Name = RolesHelper.SvaultRoles.RoleRead, NormalizedName = RolesHelper.SvaultRoles.RoleRead.ToUpper() },
/* Hosting Roles */
new Role() { Id = Guid.NewGuid(), ProductId = 2, Name = RolesHelper.HostingRoles.RoleAdmin, NormalizedName = RolesHelper.HostingRoles.RoleAdmin.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 2, Name = RolesHelper.HostingRoles.RoleCreate, NormalizedName = RolesHelper.HostingRoles.RoleCreate.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 2, Name = RolesHelper.HostingRoles.RoleDelete, NormalizedName = RolesHelper.HostingRoles.RoleDelete.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 2, Name = RolesHelper.HostingRoles.RoleEdit, NormalizedName = RolesHelper.HostingRoles.RoleEdit.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 2, Name = RolesHelper.HostingRoles.RoleRead, NormalizedName = RolesHelper.HostingRoles.RoleRead.ToUpper() },
/* VEEAM Roles */
new Role() { Id = Guid.NewGuid(), ProductId = 3, Name = RolesHelper.VEEAMRoles.RoleAdmin, NormalizedName = RolesHelper.VEEAMRoles.RoleAdmin.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 3, Name = RolesHelper.VEEAMRoles.RoleBackup, NormalizedName = RolesHelper.VEEAMRoles.RoleBackup.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 3, Name = RolesHelper.VEEAMRoles.RoleRestore, NormalizedName = RolesHelper.VEEAMRoles.RoleRestore.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 3, Name = RolesHelper.VEEAMRoles.RoleRead, NormalizedName = RolesHelper.VEEAMRoles.RoleRead.ToUpper() },
/* Mail Roles */
new Role() { Id = Guid.NewGuid(), ProductId = 4, Name = RolesHelper.MailRoles.RoleAdmin, NormalizedName = RolesHelper.MailRoles.RoleAdmin.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 4, Name = RolesHelper.MailRoles.RoleCreate, NormalizedName = RolesHelper.MailRoles.RoleCreate.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 4, Name = RolesHelper.MailRoles.RoleDelete, NormalizedName = RolesHelper.MailRoles.RoleDelete.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 4, Name = RolesHelper.MailRoles.RoleEdit, NormalizedName = RolesHelper.MailRoles.RoleEdit.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 4, Name = RolesHelper.MailRoles.RoleRead, NormalizedName = RolesHelper.MailRoles.RoleRead.ToUpper() },
/* Mail Office */
new Role() { Id = Guid.NewGuid(), ProductId = 5, Name = RolesHelper.Office365Roles.RoleAdmin, NormalizedName = RolesHelper.Office365Roles.RoleAdmin.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 5, Name = RolesHelper.Office365Roles.RoleCreate, NormalizedName = RolesHelper.Office365Roles.RoleCreate.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 5, Name = RolesHelper.Office365Roles.RoleDelete, NormalizedName = RolesHelper.Office365Roles.RoleDelete.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 5, Name = RolesHelper.Office365Roles.RoleEdit, NormalizedName = RolesHelper.Office365Roles.RoleEdit.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 5, Name = RolesHelper.Office365Roles.RoleRead, NormalizedName = RolesHelper.Office365Roles.RoleRead.ToUpper() },
/* MailProtect Roles */
new Role() { Id = Guid.NewGuid(), ProductId = 6, Name = RolesHelper.MailProtectRoles.RoleAdmin, NormalizedName = RolesHelper.MailProtectRoles.RoleAdmin.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 6, Name = RolesHelper.MailProtectRoles.RoleCreate, NormalizedName = RolesHelper.MailProtectRoles.RoleCreate.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 6, Name = RolesHelper.MailProtectRoles.RoleDelete, NormalizedName = RolesHelper.MailProtectRoles.RoleDelete.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 6, Name = RolesHelper.MailProtectRoles.RoleEdit, NormalizedName = RolesHelper.MailProtectRoles.RoleEdit.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 6, Name = RolesHelper.MailProtectRoles.RoleRead, NormalizedName = RolesHelper.MailProtectRoles.RoleRead.ToUpper() },
/* MonCloud Roles */
new Role() { Id = Guid.NewGuid(), ProductId = 7, Name = RolesHelper.MonCloudRoles.RoleAdmin, NormalizedName = RolesHelper.MonCloudRoles.RoleAdmin.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 7, Name = RolesHelper.MonCloudRoles.RoleSync, NormalizedName = RolesHelper.MonCloudRoles.RoleSync.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 7, Name = RolesHelper.MonCloudRoles.RoleRestore, NormalizedName = RolesHelper.MonCloudRoles.RoleRestore.ToUpper() },
new Role() { Id = Guid.NewGuid(), ProductId = 7, Name = RolesHelper.MonCloudRoles.RoleRead, NormalizedName = RolesHelper.MonCloudRoles.RoleRead.ToUpper() },
};
IList<GroupType> grouptypes = new List<GroupType>()
{
new GroupType() { Id = 1, Name = "Cloud Provider", PictoName = "cloud" },
new GroupType() { Id = 2, Name = "Partenaire", PictoName = "supervisor_account" },
new GroupType() { Id = 3, Name = "Client", PictoName = "group" },
new GroupType() { Id = 4, Name = "Groupe", PictoName = "folder" }
};
IList<Group> groups = new List<Group>()
{
new Group() { Id = mProvider, Name = "AGS Cloud", GroupTypeId = 1, ParentGroupId = null },
};
IList<GroupProperty> groupProperties = new List<GroupProperty>()
{
new GroupProperty() { Id = Guid.NewGuid(), ProductId = 1, GroupId = mProvider, Name = Domain.Portal.GroupProperties.community_id.ToString(), Value = Guid.Empty.ToString() }
};
IList<LicenseType> licenseTypes = new List<LicenseType>()
{
new LicenseType() { Id = 1, Name = "Cloud", IsFilterable = true, OrderBy = 1 },
new LicenseType() { Id = 2, Name = "Hybrid Mirroir", IsFilterable = true, OrderBy = 2 },
new LicenseType() { Id = 4, Name = "Hybrid Illimitée", IsFilterable = true, OrderBy = 3 },
new LicenseType() { Id = 8, Name = "Locale", IsFilterable = true, OrderBy = 4 }
};
IList<LicenseStatus> licenseStatus = new List<LicenseStatus>()
{
new LicenseStatus() { Id = -1, Name = "NotInstalled", IconName = "highlight_off", IconColor = "grey-600-fg", IsFilterable = true, OrderBy = 3 },
new LicenseStatus() { Id = 0, Name = "Online", IconName = "wifi", IconColor = "green-600-fg", IsFilterable = true, OrderBy = 1 },
new LicenseStatus() { Id = 1, Name = "Disabled", IconName = "delete", IconColor = "red-600-fg", IsFilterable = false },
new LicenseStatus() { Id = 2, Name = "MarkForDelete", IconName = "delete_forever", IconColor = "red-600-fg", IsFilterable = false },
new LicenseStatus() { Id = 4, Name = "Detached", IconName = "indeterminate_check_box", IconColor = "red-600-fg", IsFilterable = false },
new LicenseStatus() { Id = 8, Name = "Offline", IconName = "wifi_off", IconColor = "red-600-fg", IsFilterable = true, OrderBy = 2 }
};
IList<LicenseState> licenseStates = new List<LicenseState>()
{
new LicenseState() { Id = 0, Name = "NotInstalled", IconName = "highlight_off", IconColor = "grey-600-fg", IsFilterable = true, OrderBy = 9 },
new LicenseState() { Id = 1, Name = "NotConfigured", IconName = "perm_data_setting", IconColor = "grey-600-fg", IsFilterable = true, OrderBy = 8 },
new LicenseState() { Id = 2, Name = "Failed", IconName = "sms_failed", IconColor = "red-600-fg", IsFilterable = true, OrderBy = 7 },
new LicenseState() { Id = 3, Name = "NotConnected", IconName = "wifi_off", IconColor = "red-600-fg", IsFilterable = true, OrderBy = 6 },
new LicenseState() { Id = 4, Name = "Suspended", IconName = "pause", IconColor = "orange-600-fg", IsFilterable = true, OrderBy = 5 },
new LicenseState() { Id = 5, Name = "Killed", IconName = "stop", IconColor = "orange-600-fg", IsFilterable = true, OrderBy = 4 },
new LicenseState() { Id = 6, Name = "Maintenance", IconName = "outlined_flag", IconColor = "blue-600-fg", IsFilterable = true, OrderBy = 3 },
new LicenseState() { Id = 7, Name = "Running", IconName = "play_circle_outline", IconColor = "yellow-600-fg", IsFilterable = true, OrderBy = 2 },
new LicenseState() { Id = 8, Name = "Completed", IconName = "check", IconColor = "green-600-fg", IsFilterable = true, OrderBy = 1 }
};
IList<BackupMode> backupmodes = new List<BackupMode>()
{
new BackupMode() { Id = 1, Name = "Cloud", IconName = "cloud", IconColor = "blue-600-fg" },
new BackupMode() { Id = 2, Name = "Locale", IconName = "dns", IconColor = "grey-600-fg" },
new BackupMode() { Id = 4, Name = "Cloud & Locale", IconName = "all_inclusive", IconColor = "light-blue-300-fg" }
};
/* Code to allow 0 value in BackupState -> Id */
modelBuilder.Entity<LicenseState>().Property(p => p.Id).ValueGeneratedNever();
modelBuilder.Entity<BackupState>().Property(p => p.Id).ValueGeneratedNever();
modelBuilder.Entity<LicenseStatus>().Property(p => p.Id).ValueGeneratedNever();
/* End */
modelBuilder.Entity<GroupType>().HasData(grouptypes);
modelBuilder.Entity<Group>().HasData(groups);
modelBuilder.Entity<Product>().HasData(products);
modelBuilder.Entity<Role>().HasData(roles);
modelBuilder.Entity<User>().HasData(users);
modelBuilder.Entity<LicenseType>().HasData(licenseTypes);
modelBuilder.Entity<LicenseStatus>().HasData(licenseStatus);
modelBuilder.Entity<LicenseState>().HasData(licenseStates);
modelBuilder.Entity<BackupMode>().HasData(backupmodes);
modelBuilder.Entity<GroupProperty>().HasData(groupProperties);
modelBuilder.Entity<AuditType>().HasData(audittypes);
base.OnModelCreating(modelBuilder);
/* Has to be set up after base.OnModelCreating */
modelBuilder.Entity<UserRole>(userRole =>
{
userRole.HasKey(ur => new { ur.UserId, ur.RoleId });
userRole.HasOne(ur => ur.Role)
.WithMany(r => r.UserRoles)
.HasForeignKey(ur => ur.RoleId)
.IsRequired();
userRole.HasOne(ur => ur.User)
.WithMany(r => r.UserRoles)
.HasForeignKey(ur => ur.UserId)
.IsRequired();
});
modelBuilder.Entity<GroupProperty>().HasIndex(b => b.Name);
modelBuilder.Entity<GroupProperty>().HasIndex(b => b.Value);
/*modelBuilder.Entity<Group>().HasOne(b => b.ParentGroup)
.WithMany(b => b.ChildGroupsHidden)
.HasForeignKey(b => b.ParentGroupId)
.OnDelete(DeleteBehavior.Restrict);*/
}
}
因此，当我最初创建我的第一个迁移时，我使用了以下内容：
Add-Migration "Initialization" -o "Data\Migrations"
但是每次我尝试添加第二个迁移时，当我想向表中添加新字段时，都会出现此错误，提示Value cannot be null (Parameter: Key)
public class Audit
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
public Guid GroupId { get; set; }
[ForeignKey(nameof(GroupId))]
public Group Group { get; set; }
public Guid UserId { get; set; }
[ForeignKey(nameof(UserId))]
public User User { get; set; }
public int AuditTypeId { get; set; }
[ForeignKey(nameof(AuditTypeId))]
public AuditType AuditType { get; set; }
public string IP { get; set; }
public string BrowserInfo { get; set; }
public string OriginalObject { get; set; }
public string UpdatedObject { get; set; }
public DateTime CreationTime { get; set; }
**public string TestField { get; set; }**
}
有人对我为什么无法添加第二个迁移有任何想法吗？ 显示的错误是：
PM> Add-Migration "Test_Audit"
Build started...
Build succeeded.
Microsoft.EntityFrameworkCore.Infrastructure[10403]
Entity Framework Core 3.1.2 initialized 'DataContext' using provider 'Microsoft.EntityFrameworkCore.SqlServer' with options: None
Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (13ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT 1
Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (12ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT OBJECT_ID(N'[__EFMigrationsHistory]');
Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (1ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT 1
Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (0ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT OBJECT_ID(N'[__EFMigrationsHistory]');
Microsoft.EntityFrameworkCore.Database.Command[20101]
Executed DbCommand (1ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT [MigrationId], [ProductVersion]
FROM [__EFMigrationsHistory]
ORDER BY [MigrationId];
Microsoft.EntityFrameworkCore.Migrations[20405]
No migrations were applied. The database is already up to date.
Microsoft.EntityFrameworkCore.Infrastructure[10403]
Entity Framework Core 3.1.2 initialized 'DataContext' using provider 'Microsoft.EntityFrameworkCore.SqlServer' with options: None
System.ArgumentNullException: Value cannot be null. (Parameter 'key')
at System.Collections.Generic.Dictionary`2.FindEntry(TKey key)
at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.EntityReferenceMap.TryGet(Object entity, IEntityType entityType, InternalEntityEntry& entry, Boolean throwOnNonUniqueness)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.TryGetEntry(Object entity, IEntityType entityType, Boolean throwOnTypeMismatch)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.NavigationFixer.KeyPropertyChanged(InternalEntityEntry entry, IProperty property, IReadOnlyList`1 containingPrincipalKeys, IReadOnlyList`1 containingForeignKeys, Object oldValue, Object newValue)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntryNotifier.KeyPropertyChanged(InternalEntityEntry entry, IProperty property, IReadOnlyList`1 keys, IReadOnlyList`1 foreignKeys, Object oldValue, Object newValue)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.ChangeDetector.DetectKeyChange(InternalEntityEntry entry, IProperty property)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.ChangeDetector.PropertyChanged(InternalEntityEntry entry, IPropertyBase propertyBase, Boolean setModified)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntryNotifier.PropertyChanged(InternalEntityEntry entry, IPropertyBase property, Boolean setModified)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetProperty(IPropertyBase propertyBase, Object value, Boolean isMaterialization, Boolean setModified, Boolean isCascadeDelete, CurrentValueType valueType)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetProperty(IPropertyBase propertyBase, Object value, Boolean isMaterialization, Boolean setModified, Boolean isCascadeDelete)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.CascadeDelete(InternalEntityEntry entry, Boolean force, IEnumerable`1 foreignKeys)
at Microsoft.EntityFrameworkCore.Update.Internal.UpdateAdapter.CascadeDelete(IUpdateEntry entry, IEnumerable`1 foreignKeys)
at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDataOperations(DiffContext diffContext)+MoveNext()
at System.Linq.Enumerable.ConcatIterator`1.MoveNext()
at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Sort(IEnumerable`1 operations, DiffContext diffContext)
at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDifferences(IModel source, IModel target)
at Microsoft.EntityFrameworkCore.Migrations.Design.MigrationsScaffolder.ScaffoldMigration(String migrationName, String rootNamespace, String subNamespace, String language)
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)
Value cannot be null. (Parameter 'key')
我的理解是，以某种方式，我们有一个初始化为null的Key字段，因此它无法创建新的迁移，但是我无法找到问题的根源。奇怪的是，第一次迁移可以正常工作。
任何帮助将不胜感激，谢谢大家！
答案 0 :(得分：1)
根据评论进行编辑
“ ......我们必须使用固定的Guid或固定的ID。否则，任何后续迁移都将使用Guid.NewGuid（）生成该新的Guid / Id，并尝试播种该新数据，很遗憾，因为我们已经链接了那些带有某些外键的ID，EF无法继续。”
进行初始（或任何）迁移后，请确保运行Update-Database命令以应用迁移。从更新中应用完之后，您可以根据需要在应用程序开发中进行新的迁移，更新和重复。
例如：
对ef模型，代码等进行更改，然后运行add migration命令：
Add-Migration NewMigrationAfterChanges
使用update db命令应用迁移：
Update-Database
现在，您可以进行更改并添加新的迁移，前提是该迁移已更新且没有错误或发生了意外情况。有关使用EF内核的更多详细信息，请参见MSDN on EF。
答案 1 :(得分：1)
在@CoderLee经过数小时的研究和帮助之后，我发现在播种数据时不应使用Guid.NewGuid（），这将导致后续的迁移根据已使用的Guid一次又一次地尝试播种数据。通过某些外键。