Error the entity type requires a primary key

Question

I would like to expand the question asked on this thread  Binding listbox to observablecollection  by giving it an ability to persistent the data  The structure is mostly the same except I installed Entity Framework Core  created a DbContext class to hold the records  I added a button to save the dataset to SQL Server  I did not encounter the compiling error but when I attempted to save the data in the database I got this run time exception      Message The entity type  Fruit  requires a primary key to be defined    The whole exception in its entirety is listed below     System InvalidOperationException was unhandled   HResult -2146233079   Message The entity type  Fruit  requires a primary key to be defined    Source Microsoft EntityFrameworkCore   StackTrace    at Microsoft EntityFrameworkCore Internal ModelValidator ShowError String message    at Microsoft EntityFrameworkCore Internal ModelValidator EnsureNonNullPrimaryKeys IModel model    at Microsoft EntityFrameworkCore Internal ModelValidator Validate IModel model    at Microsoft EntityFrameworkCore Internal RelationalModelValidator Validate IModel model    at Microsoft EntityFrameworkCore Infrastructure ModelSource CreateModel DbContext context  IConventionSetBuilder conventionSetBuilder  IModelValidator validator    at Microsoft EntityFrameworkCore Infrastructure ModelSource  lt  c  DisplayClass14 0 b  0 Object k    at System Collections Concurrent ConcurrentDictionary2 GetOrAdd TKey key  Func2 valueFactory    at Microsoft EntityFrameworkCore Infrastructure ModelSource GetModel DbContext context  IConventionSetBuilder conventionSetBuilder  IModelValidator validator    at Microsoft EntityFrameworkCore Internal DbContextServices CreateModel     at Microsoft EntityFrameworkCore Internal LazyRef1 get Value     at Microsoft EntityFrameworkCore Internal DbContextServices get Model     at Microsoft EntityFrameworkCore Infrastructure EntityFrameworkServiceCollectionExtensions  lt  gt c  lt AddEntityFramework gt b  0 6 IServiceProvider p    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteRuntimeResolver VisitFactoryService FactoryService factoryService  ServiceProvider provider    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteVisitor2 VisitCallSite IServiceCallSite callSite  TArgument argument    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteRuntimeResolver VisitScoped ScopedCallSite scopedCallSite  ServiceProvider provider    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteVisitor2 VisitCallSite IServiceCallSite callSite  TArgument argument    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteRuntimeResolver VisitConstructor ConstructorCallSite constructorCallSite  ServiceProvider provider    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteVisitor2 VisitCallSite IServiceCallSite callSite  TArgument argument    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteRuntimeResolver VisitScoped ScopedCallSite scopedCallSite  ServiceProvider provider    at Microsoft Extensions DependencyInjection ServiceLookup CallSiteVisitor2 VisitCallSite IServiceCallSite callSite  TArgument argument    at Microsoft Extensions DependencyInjection ServiceProvider  lt  gt c  DisplayClass16 0  lt RealizeService gt b  0 ServiceProvider provider    at Microsoft Extensions DependencyInjection ServiceProvider GetService Type serviceType    at Microsoft Extensions DependencyInjection ServiceProviderServiceExtensions GetService T  IServiceProvider provider    at Microsoft EntityFrameworkCore Infrastructure AccessorExtensions GetService TService  IInfrastructure1 accessor    at Microsoft EntityFrameworkCore ChangeTracking ChangeTracker get StateManager     at Microsoft EntityFrameworkCore ChangeTracking ChangeTracker DetectChanges     at Microsoft EntityFrameworkCore DbContext TryDetectChanges     at Microsoft EntityFrameworkCore DbContext SaveChanges Boolean acceptAllChangesOnSuccess    at Microsoft EntityFrameworkCore DbContext SaveChanges     at Fruits MainWindow SaveFruitCommandBinding Executed Object sender  ExecutedRoutedEventArgs e  in D  Frank Test Fruits Fruits MainWindow xaml cs line 50   at System Windows Input CommandBinding OnExecuted Object sender  ExecutedRoutedEventArgs e    at System Windows Input CommandManager ExecuteCommandBinding Object sender  ExecutedRoutedEventArgs e  CommandBinding commandBinding    at System Windows Input CommandManager FindCommandBinding CommandBindingCollection commandBindings  Object sender  RoutedEventArgs e  ICommand command  Boolean execute    at System Windows Input CommandManager FindCommandBinding Object sender  RoutedEventArgs e  ICommand command  Boolean execute    at System Windows Input CommandManager OnExecuted Object sender  ExecutedRoutedEventArgs e               at System Windows UIElement OnExecutedThunk Object sender  ExecutedRoutedEventArgs e               at System Windows Input ExecutedRoutedEventArgs InvokeEventHandler Delegate genericHandler  Object target               at System Windows RoutedEventArgs InvokeHandler Delegate handler  Object target               at System Windows RoutedEventHandlerInfo InvokeHandler Object target  RoutedEventArgs routedEventArgs               at System Windows EventRoute InvokeHandlersImpl Object source  RoutedEventArgs args  Boolean reRaised               at System Windows UIElement RaiseEventImpl DependencyObject sender  RoutedEventArgs args               at System Windows UIElement RaiseEvent RoutedEventArgs args  Boolean trusted               at System Windows Input RoutedCommand ExecuteImpl Object parameter  IInputElement target  Boolean userInitiated               at System Windows Input RoutedCommand ExecuteCore Object parameter  IInputElement target  Boolean userInitiated               at MS Internal Commands CommandHelpers CriticalExecuteCommandSource ICommandSource commandSource  Boolean userInitiated               at System Windows Controls Primitives ButtonBase OnClick                at System Windows Controls Button OnClick                at System Windows Controls Primitives ButtonBase OnMouseLeftButtonUp MouseButtonEventArgs e               at System Windows UIElement OnMouseLeftButtonUpThunk Object sender  MouseButtonEventArgs e               at System Windows Input MouseButtonEventArgs InvokeEventHandler Delegate genericHandler  Object genericTarget               at System Windows RoutedEventArgs InvokeHandler Delegate handler  Object target               at System Windows RoutedEventHandlerInfo InvokeHandler Object target  RoutedEventArgs routedEventArgs               at System Windows EventRoute InvokeHandlersImpl Object source  RoutedEventArgs args  Boolean reRaised               at System Windows UIElement ReRaiseEventAs DependencyObject sender  RoutedEventArgs args  RoutedEvent newEvent               at System Windows UIElement OnMouseUpThunk Object sender  MouseButtonEventArgs e               at System Windows Input MouseButtonEventArgs InvokeEventHandler Delegate genericHandler  Object genericTarget               at System Windows RoutedEventArgs InvokeHandler Delegate handler  Object target               at System Windows RoutedEventHandlerInfo InvokeHandler Object target  RoutedEventArgs routedEventArgs               at System Windows EventRoute InvokeHandlersImpl Object source  RoutedEventArgs args  Boolean reRaised               at System Windows UIElement RaiseEventImpl DependencyObject sender  RoutedEventArgs args               at System Windows UIElement RaiseTrustedEvent RoutedEventArgs args               at System Windows UIElement RaiseEvent RoutedEventArgs args  Boolean trusted               at System Windows Input InputManager ProcessStagingArea                at System Windows Input InputManager ProcessInput InputEventArgs input               at System Windows Input InputProviderSite ReportInput InputReport inputReport               at System Windows Interop HwndMouseInputProvider ReportInput IntPtr hwnd  InputMode mode  Int32 timestamp  RawMouseActions actions  Int32 x  Int32 y  Int32 wheel               at System Windows Interop HwndMouseInputProvider FilterMessage IntPtr hwnd  WindowMessage msg  IntPtr wParam  IntPtr lParam  Boolean amp  handled               at System Windows Interop HwndSource InputFilterMessage IntPtr hwnd  Int32 msg  IntPtr wParam  IntPtr lParam  Boolean amp  handled               at MS Win32 HwndWrapper WndProc IntPtr hwnd  Int32 msg  IntPtr wParam  IntPtr lParam  Boolean amp  handled               at MS Win32 HwndSubclass DispatcherCallbackOperation Object o               at System Windows Threading ExceptionWrapper InternalRealCall Delegate callback  Object args  Int32 numArgs               at System Windows Threading ExceptionWrapper TryCatchWhen Object source  Delegate callback  Object args  Int32 numArgs  Delegate catchHandler               at System Windows Threading Dispatcher LegacyInvokeImpl DispatcherPriority priority  TimeSpan timeout  Delegate method  Object args  Int32 numArgs               at MS Win32 HwndSubclass SubclassWndProc IntPtr hwnd  Int32 msg  IntPtr wParam  IntPtr lParam               at MS Win32 UnsafeNativeMethods DispatchMessage MSG amp  msg               at System Windows Threading Dispatcher PushFrameImpl DispatcherFrame frame               at System Windows Threading Dispatcher PushFrame DispatcherFrame frame               at System Windows Application RunDispatcher Object ignore               at System Windows Application RunInternal Window window               at System Windows Application Run Window window               at System Windows Application Run                at Fruits App Main                at System AppDomain  nExecuteAssembly RuntimeAssembly assembly  String   args               at System AppDomain ExecuteAssembly String assemblyFile  Evidence assemblySecurity  String   args               at Microsoft VisualStudio HostingProcess HostProc RunUsersAssembly                at System Threading ThreadHelper ThreadStart Context Object state               at System Threading ExecutionContext RunInternal ExecutionContext executionContext  ContextCallback callback  Object state  Boolean preserveSyncCtx               at System Threading ExecutionContext Run ExecutionContext executionContext  ContextCallback callback  Object state  Boolean preserveSyncCtx               at System Threading ExecutionContext Run ExecutionContext executionContext  ContextCallback callback  Object state               at System Threading ThreadHelper ThreadStart           InnerException     This is the updated class Fruit   namespace Fruits ViewModels        Table  Fruits        public  class Fruit   ViewModelBase                region Constractor         public Fruit                               public Fruit string name  String clrString                        FruitName   name                  Parse colors like so   Color ColorConverter ConvertFromString clrString               FruitColor   clrString               id   Guid NewGuid                      public Fruit string name  Color clr                        FruitName   name              FruitColor   clr ToString                 id   Guid NewGuid                        endregion           region Properties         private Guid  id           Key          public Guid ID                       get   return  id                        region FruitName         private string  fruitname          public string FruitName                       get                               return  fruitname                            set                               if   fruitname    value                                         fruitname   value                      OnPropertyChanged  FruitName                                                       endregion           region FruitColor         private String  fruitcolor          public String FruitColor                       get                               return  fruitcolor                            set                               if   fruitcolor    value                                         fruitcolor   value                      OnPropertyChanged  FruitColor                                                       endregion           region Selected Property         private bool  isSelected   true              NOTE  I renamed this property         public bool IsSelected                       get                               return  isSelected                            set                               if   isSelected    value                                         isSelected   value                      OnPropertyChanged  IsSelected                                                       endregion           endregion           The updated MainWindows xaml  to add a save button    lt Window x Class  Fruits MainWindow          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          xmlns d  http   schemas microsoft com expression blend 2008          xmlns mc  http   schemas openxmlformats org markup-compatibility 2006          xmlns local  clr-namespace Fruits          mc Ignorable  d          Title  MainWindow  Height  350  Width  525  gt       lt Window Resources gt           lt RoutedCommand x Key  AddFruit    gt           lt RoutedCommand x Key  SaveFruit    gt       lt  Window Resources gt       lt Window CommandBindings gt           lt CommandBinding Command   StaticResource AddFruit                                           Executed  AddFruitCommandBinding Executed                                          CanExecute  AddFruitCommandBinding CanExecute    gt           lt CommandBinding Command   StaticResource SaveFruit                                           Executed  SaveFruitCommandBinding Executed                                          CanExecute  SaveFruitCommandBinding CanExecute    gt       lt  Window CommandBindings gt       lt Grid gt           lt StackPanel Orientation  Vertical                                  Margin  10  gt               lt CheckBox IsChecked   Binding ShowSelectedFruitOnly   gt Selected Fruit Only lt  CheckBox gt               lt ListBox x Name  MyList                               ItemsSource   Binding FruitsView                                ItemTemplate   StaticResource FruitTemp     gt               lt StackPanel Orientation  Horizontal                                      Margin  0 10 0 0  gt                   lt Label Width  100  gt New Name  lt  Label gt                   lt TextBox Width  200                                   Text   Binding NewFruitName  Mode TwoWay                                        gt               lt  StackPanel gt               lt StackPanel Orientation  Horizontal                                      Margin  0 10 0 0  gt                   lt Label Width  100  gt New Color  lt  Label gt                   lt  -- lt TextBox Width  200                                   Text   Binding NewFruitColor  UpdateSourceTrigger PropertyChanged     gt -- gt                   lt TextBox Width  200                                   Text   Binding NewFruitColor  Mode TwoWay      gt                    lt ContentControl Style   StaticResource ColorSwatch                                                   Margin  2                                                  VerticalAlignment  Center                                                  Content   Binding NewFruitColor     gt               lt  StackPanel gt               lt StackPanel Orientation  Horizontal  gt               lt Button x Name  AddFruit                              Height  auto                              Width  auto                              Content  Add New Fruit 2                              Margin  0 10 0 0                              Command   StaticResource AddFruit     gt                   lt Button x Name  SaveFruit                                  Height  auto                                  Width  auto                                  Content  Save Fruit                                  Margin  100 10 0 0                                  Command   StaticResource SaveFruit     gt               lt  StackPanel gt           lt  StackPanel gt       lt  Grid gt   lt  Window gt    and my code behind the mainwindows  added handler   using Fruits ViewModels  using System  using System Windows  using System Windows Input   namespace Fruits            lt summary gt          Interaction logic for MainWindow xaml          lt  summary gt      public partial class MainWindow   Window               public MainWindow                         InitializeComponent                DataContext   new MainViewModel                 ViewModel AddNewFruit  Jackfruit    Yellow                ViewModel AddNewFruit  Watermelon    ForestGreen                ViewModel AddNewFruit  Apple    Red                ViewModel AddNewFruit  Banana    Yellow                ViewModel AddNewFruit  Orange    DeepSkyBlue                   ViewModel Fruits 0  IsSelected   false                ViewModel Fruits 1  IsSelected   false               ViewModel FruitsView Refresh                       public MainViewModel ViewModel   get   return DataContext as MainViewModel               private void AddFruitCommandBinding Executed object sender  ExecutedRoutedEventArgs e                        ViewModel AddNewFruit                       private void AddFruitCommandBinding CanExecute object sender  CanExecuteRoutedEventArgs e                        e CanExecute                       ViewModel    null                      amp  amp   String IsNullOrWhiteSpace ViewModel NewFruitName                       amp  amp   String IsNullOrWhiteSpace ViewModel NewFruitColor                                           private void SaveFruitCommandBinding Executed object sender  ExecutedRoutedEventArgs e                        using  var db new FruitDbContext                                  db SaveChanges                                     private void SaveFruitCommandBinding CanExecute object sender  CanExecuteRoutedEventArgs e                        e CanExecute   true                      My newly added dbContext   namespace Fruits ViewModels       public class FruitDbContext DbContext               public DbSet lt Fruit gt  Fruits   get  set            protected override void OnConfiguring DbContextOptionsBuilder optionBuilder                        optionBuilder UseSqlServer   Server   xxx  Database Test  Integrated Security   True                        Other classes remain unchanged  but I listed them anyway   ViewModelBase      namespace Fruits ViewModels               public  class ViewModelBase   INotifyPropertyChanged                       public event PropertyChangedEventHandler PropertyChanged              public void OnPropertyChanged string name                                if  PropertyChanged    null                                        PropertyChanged this  new PropertyChangedEventArgs name                                                     ViewModel  using System  using System Collections ObjectModel  using System ComponentModel  using System Windows Data  using System Windows Media   namespace Fruits ViewModels         region MainViewModel Class     public class MainViewModel   ViewModelBase               public  MainViewModel                         Fruits   new ObservableCollection lt Fruit gt                        public ICollectionView FruitsView   get  private set              region ShowSelectedFruitOnly Property         private bool  showSelectedFruitOnly   true          public bool ShowSelectedFruitOnly                       get   return  showSelectedFruitOnly                set                               if  value     showSelectedFruitOnly                                         showSelectedFruitOnly   value                      FruitsView Refresh                        OnPropertyChanged  ShowSelectedFruitOnly                                                       endregion ShowSelectedFruitOnly Property           region Add Methods         public void AddNewFruit                         Fruits Add new Fruit NewFruitName  NewFruitColor                 NewFruitName                   NewFruitColor                         public void AddNewFruit string name  string color                        Fruits Add new Fruit name  color                      public void AddNewFruit string name  Color color                        Fruits Add new Fruit name  color                       endregion Add Methods           region NewFruitName Property         private String  newFruitName   default String           public String NewFruitName                       get   return  newFruitName                set                               if  value     newFruitName                                         newFruitName   value                      OnPropertyChanged  NewFruitName                                                       endregion NewFruitName Property           region NewFruitColor Property         private String  newFruitColor   default String           public String NewFruitColor                       get   return  newFruitColor                set                               if  value     newFruitColor                                         newFruitColor   value                      OnPropertyChanged  NewFruitColor                                                       endregion NewFruitColor Property           region Fruits Property         private static ObservableCollection lt Fruit gt   fruits          public ObservableCollection lt Fruit gt  Fruits                       get   return  fruits                private set                               if  value     fruits                                         fruits   value                       FruitsView   CollectionViewSource GetDefaultView Fruits                        FruitsView Filter   FruitFilterPredicate                      FruitsView Refresh                         OnPropertyChanged  Fruits                                                      protected bool FruitFilterPredicate Object o                        if  ShowSelectedFruitOnly                                return  o as Fruit  IsSelected                             return true                     endregion Fruits Property             endregion MainViewModel Class     App xaml   lt Application x Class  Fruits App               xmlns  http   schemas microsoft com winfx 2006 xaml presentation               xmlns x  http   schemas microsoft com winfx 2006 xaml               xmlns local  clr-namespace Fruits               StartupUri  MainWindow xaml  gt       lt Application Resources gt           lt Style x Key  ColorSwatch                       TargetType  ContentControl  gt               lt Setter Property  Width                              Value  24    gt               lt Setter Property  Height                              Value  24    gt               lt Setter Property  IsTabStop                              Value  false    gt               lt Setter Property  ContentTemplate  gt                   lt Setter Value gt                       lt DataTemplate gt                           lt Rectangle HorizontalAlignment  Stretch                                               VerticalAlignment  Stretch                                               Stroke  Gray                                               StrokeThickness  1  gt                               lt Rectangle Fill gt                                   lt SolidColorBrush Color   Binding     gt                               lt  Rectangle Fill gt                           lt  Rectangle gt                       lt  DataTemplate gt                   lt  Setter Value gt               lt  Setter gt           lt  Style gt            lt DataTemplate x Key  FruitTemp  gt               lt StackPanel Orientation  Horizontal                                      Margin  5  gt                   lt TextBlock x Name  tbName                                       Text   Binding FruitName                                        Margin  10 0 0 0                                       Width  100    gt                   lt TextBlock x Name  tbColor                                       Text   Binding FruitColor                                        Margin  10 0 0 0                                       Width  100    gt                   lt ContentControl Width  16                                                  Height  16                                                  Style   StaticResource ColorSwatch                                                   Content   Binding FruitColor     gt                   lt  -- The problem here was you were trying to bind Checked  an event                   instead if IsChecked  a bool  property                   -- gt                   lt CheckBox x Name  cbSelected                                      Content  Selected                                      Margin  10 0 0 0                                      IsChecked   Binding IsSelected     gt               lt  StackPanel gt           lt  DataTemplate gt       lt  Application Resources gt   lt  Application gt    The structure of my project    My table in SQL Server   CREATE TABLE  dbo   Fruits         ID   uniqueidentifier  NOT NULL       FruitName   nvarchar  50  NULL       FruitColor   nvarchar  50  NULL       IsSelected   nvarchar  1  NULL        CONSTRAINT  PK Fruit           PRIMARY KEY CLUSTERED   ID  ASC                      WITH  PAD INDEX   OFF  STATISTICS NORECOMPUTE   OFF                             IGNORE DUP KEY   OFF  ALLOW ROW LOCKS   ON                             ALLOW PAGE LOCKS   ON  ON  PRIMARY    ON  PRIMARY    Please advise why the message said there was no primary key while it does exist

User · Answer

Make sure you have the following condition:

Use [key] if your primary key name is not Id or ID.
Use the public keyword.
Primary key should have getter and setter.

Example:

public class MyEntity {
   [key]
   public Guid Id {get; set;}
}

User · Answer

None of the answers worked until I removed the HasNoKey   method from the entity  Dont forget to remove this from your data context or the  Key  attribute will not fix anything

User · Answer

Yet another reason may be that your entity class has several properties named somhow    id i - so ending with ID case insensitive AND elementary type AND there is no  Key  attribute  EF will namely try to figure out the PK by itself by looking for elementary typed properties ending in ID  See my case  public class MyTest  IMustHaveTenant     public long Id   get  set      public int TenantId   get  set       MaxLength 32     public virtual string Signum  get  set      public virtual string ID   get  set      public virtual string ID Other   get  set       don t ask - lecacy code  The Id was even inherited  so I could not use  Key   just simplifying the code here  But here EF is totally confused  What helped was using modelbuilder this in DBContext class              modelBuilder Entity lt MyTest gt  f   gt                                f HasKey e   gt  e Id                   f HasIndex e   gt  new   e TenantId                     f HasIndex e   gt  new   e TenantId  e ID Other                      the index on PK is implicit

User · Answer

Your Id property needs to have a setter  However the setter can be private  The  Key  attribute is not necessary if the property is named  Id  as it will find it through the naming convention where it looks for a key with the name  Id    public Guid Id   get                    Will not work public Guid Id   get  set               Will work public Guid Id   get  private set       Will also work

User · Answer

I found a bit different cause of the error  It seems like SQLite wants to use correct primary key class property name  So     Wrong PK name  public class Client     public int SomeFieldName   get  set        It is the ID           Correct PK name  public class Client     public int Id   get  set        It is the ID          public class Client     public int ClientId   get  set        It is the ID           It still posible to use wrong PK name but we have to use  Key  attribute like   public class Client       Key     public int SomeFieldName   get  set        It is the ID

User · Answer

The entity type  DisplayFormatAttribute  requires a primary key to be   defined    In my case I figured out the problem was that I used properties like this   public string LastName   get  set       OK public string Address   get  set        OK  public string State   get  set          OK public int  Zip   get  set              OK public EmailAddressAttribute Email   get  set       NOT OK public PhoneAttribute PhoneNumber   get  set        NOT OK   Not sure if there is a better way to solve it but I changed the Email and PhoneNumber attribute to a string  Problem solved

User · Answer

This worked for me   using System ComponentModel DataAnnotations    Key  public int ID   get  set

User · Answer

When I used the Scaffold-DbContext command  it didn t include the  quot  key  quot  annotation in the model files or the  quot entity HasKey     quot  entry in the  quot modelBuilder Entity quot  blocks  My solution was to add a line like this in every  quot modelBuilder Entity quot  block in the  Context cs file  entity HasKey X   gt  x Id    I m not saying this is better  or even the right way  I m just saying that it worked for me

User · Answer

I came here with similar error      System InvalidOperationException   The entity type  MyType  requires a primary key to be defined     After reading answer by hvd  realized I had simply forgotten to make my key property  public   This    namespace MyApp Models Schedule       public class MyType                Key          int Id   get  set                      Should be this    namespace MyApp Models Schedule       public class MyType                Key          public int Id   get  set        must be public

User · Answer

This exception message doesn t mean it requires a primary key to be defined in your database  it means it requires a primary key to be defined in your class   Although you ve attempted to do so    private Guid  id   Key  public Guid ID       get   return  id         This has no effect  as Entity Framework ignores read-only properties  It has to  when it retrieves a Fruits record from the database  it constructs a Fruit object  and then calls the property setters for each mapped property  That s never going to work for read-only properties   You need Entity Framework to be able to set the value of ID  This means the property needs to have a setter

User · Answer

Removed and added back in the table using Scaffold-DbContext and the error went away

[c#] Error: the entity type requires a primary key

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