ModelBuilder API for sentinels

src/EFCore/Metadata/Builders/IConventionPropertyBuilder.cs

@@ -161,6 +161,24 @@ public interface IConventionPropertyBuilder : IConventionPropertyBaseBuilder
     /// <returns><see langword="true" /> if the maximum length of data allowed can be set for this property.</returns>
     bool CanSetMaxLength(int? maxLength, bool fromDataAnnotation = false);
 
+    /// <summary>
+    ///     Configures the value that will be used to determine if the property has been set or not. If the property is set to the
+    ///     sentinel value, then it is considered not set. By default, the sentinel value is the CLR default value for the type of
+    ///     the property.
+    /// </summary>
+    /// <param name="sentinel">The sentinel value.</param>
+    /// <param name="fromDataAnnotation">Indicates whether the configuration was specified using a data annotation.</param>
+    /// <returns>The same builder instance if the configuration was applied, <see langword="null" /> otherwise.</returns>
+    IConventionPropertyBuilder? HasSentinel(object? sentinel, bool fromDataAnnotation = false);
+
+    /// <summary>
+    ///     Returns a value indicating whether the sentinel can be set for this property from the current configuration source.
+    /// </summary>
+    /// <param name="sentinel">The sentinel value.</param>
+    /// <param name="fromDataAnnotation">Indicates whether the configuration was specified using a data annotation.</param>
+    /// <returns><see langword="true" /> if the sentinel can be set for this property.</returns>
+    bool CanSetSentinel(object? sentinel, bool fromDataAnnotation = false);
+
     /// <summary>
     ///     Configures whether the property as capable of persisting unicode characters.
     /// </summary>

src/EFCore/Metadata/Builders/PropertiesConfigurationBuilder.cs

@@ -69,6 +69,20 @@ public virtual PropertiesConfigurationBuilder HaveMaxLength(int maxLength)
         return this;
     }
 
+    /// <summary>
+    ///     Configures the value that will be used to determine if the property has been set or not. If the property is set to the
+    ///     sentinel value, then it is considered not set. By default, the sentinel value is the CLR default value for the type of
+    ///     the property.
+    /// </summary>
+    /// <param name="sentinel">The sentinel value.</param>
+    /// <returns>The same builder instance so that multiple configuration calls can be chained.</returns>
+    public virtual PropertiesConfigurationBuilder HaveSentinel(object? sentinel)
+    {
+        Configuration.SetSentinel(sentinel);
+
+        return this;
+    }
+
     /// <summary>
     ///     Configures the precision and scale of the property.
     /// </summary>

src/EFCore/Metadata/Builders/PropertyBuilder.cs

@@ -95,6 +95,20 @@ public virtual PropertyBuilder HasMaxLength(int maxLength)
         return this;
     }
 
+    /// <summary>
+    ///     Configures the value that will be used to determine if the property has been set or not. If the property is set to the
+    ///     sentinel value, then it is considered not set. By default, the sentinel value is the CLR default value for the type of
+    ///     the property.
+    /// </summary>
+    /// <param name="sentinel">The sentinel value.</param>
+    /// <returns>The same builder instance if the configuration was applied, <see langword="null" /> otherwise.</returns>
+    public virtual PropertyBuilder HasSentinel(object? sentinel)
+    {
+        Builder.HasSentinel(sentinel, ConfigurationSource.Explicit);
+
+        return this;
+    }
+
     /// <summary>
     ///     Configures the precision and scale of the property.
     /// </summary>

src/EFCore/Metadata/Builders/PropertyBuilder`.cs

@@ -63,6 +63,16 @@ public PropertyBuilder(IMutableProperty property)
     public new virtual PropertyBuilder<TProperty> HasMaxLength(int maxLength)
         => (PropertyBuilder<TProperty>)base.HasMaxLength(maxLength);
 
+    /// <summary>
+    ///     Configures the value that will be used to determine if the property has been set or not. If the property is set to the
+    ///     sentinel value, then it is considered not set. By default, the sentinel value is the CLR default value for the type of
+    ///     the property.
+    /// </summary>
+    /// <param name="sentinel">The sentinel value.</param>
+    /// <returns>The same builder instance if the configuration was applied, <see langword="null" /> otherwise.</returns>
+    public new virtual PropertyBuilder<TProperty> HasSentinel(object? sentinel)
+        => (PropertyBuilder<TProperty>)base.HasSentinel(sentinel);
+
     /// <summary>
     ///     Configures the precision and scale of the property.
     /// </summary>

src/EFCore/Metadata/Builders/TypeMappingConfigurationBuilder.cs

@@ -74,6 +74,20 @@ public virtual TypeMappingConfigurationBuilder HasMaxLength(int maxLength)
         return this;
     }
 
+    /// <summary>
+    ///     Configures the value that will be used to determine if the property has been set or not. If the property is set to the
+    ///     sentinel value, then it is considered not set. By default, the sentinel value is the CLR default value for the type of
+    ///     the property.
+    /// </summary>
+    /// <param name="sentinel">The sentinel value.</param>
+    /// <returns>The same builder instance if the configuration was applied, <see langword="null" /> otherwise.</returns>
+    public virtual TypeMappingConfigurationBuilder HasSentinel(object? sentinel)
+    {
+        Configuration.SetSentinel(sentinel);
+
+        return this;
+    }
+
     /// <summary>
     ///     Configures the precision and scale of the property.
     /// </summary>

src/EFCore/Metadata/Builders/TypeMappingConfigurationBuilder`.cs

@@ -53,6 +53,16 @@ public TypeMappingConfigurationBuilder(PropertyConfiguration scalar)
     public new virtual TypeMappingConfigurationBuilder<TProperty> HasMaxLength(int maxLength)
         => (TypeMappingConfigurationBuilder<TProperty>)base.HasMaxLength(maxLength);
 
+    /// <summary>
+    ///     Configures the value that will be used to determine if the property has been set or not. If the property is set to the
+    ///     sentinel value, then it is considered not set. By default, the sentinel value is the CLR default value for the type of
+    ///     the property.
+    /// </summary>
+    /// <param name="sentinel">The sentinel value.</param>
+    /// <returns>The same builder instance if the configuration was applied, <see langword="null" /> otherwise.</returns>
+    public new virtual TypeMappingConfigurationBuilder<TProperty> HasSentinel(object? sentinel)
+        => (TypeMappingConfigurationBuilder<TProperty>)base.HasSentinel(sentinel);
+
     /// <summary>
     ///     Configures the precision and scale of the property.
     /// </summary>

src/EFCore/Metadata/Internal/CoreAnnotationNames.cs

@@ -19,6 +19,14 @@ public static class CoreAnnotationNames
     /// </summary>
     public const string MaxLength = "MaxLength";
 
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public const string Sentinel = "Sentinel";
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
@@ -317,6 +325,7 @@ public static class CoreAnnotationNames
     public static readonly ISet<string> AllNames = new HashSet<string>
     {
         MaxLength,
+        Sentinel,
         Precision,
         Scale,
         Unicode,

src/EFCore/Metadata/Internal/InternalPropertyBuilder.cs

@@ -193,6 +193,34 @@ public virtual bool CanSetMaxLength(int? maxLength, ConfigurationSource? configu
         => configurationSource.Overrides(Metadata.GetMaxLengthConfigurationSource())
             || Metadata.GetMaxLength() == maxLength;
 
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual InternalPropertyBuilder? HasSentinel(object? sentinel, ConfigurationSource configurationSource)
+    {
+        if (CanSetSentinel(sentinel, configurationSource))
+        {
+            Metadata.SetSentinel(sentinel, configurationSource);
+
+            return this;
+        }
+
+        return null;
+    }
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual bool CanSetSentinel(object? sentinel, ConfigurationSource? configurationSource)
+        => configurationSource.Overrides(Metadata.GetSentinelConfigurationSource())
+            || Equals(Metadata.Sentinel, sentinel);
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
@@ -1013,6 +1041,24 @@ bool IConventionPropertyBaseBuilder.CanSetPropertyAccessMode(PropertyAccessMode?
     bool IConventionPropertyBuilder.CanSetMaxLength(int? maxLength, bool fromDataAnnotation)
         => CanSetMaxLength(maxLength, fromDataAnnotation ? ConfigurationSource.DataAnnotation : ConfigurationSource.Convention);
 
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    IConventionPropertyBuilder? IConventionPropertyBuilder.HasSentinel(object? sentinel, bool fromDataAnnotation)
+        => HasSentinel(sentinel, fromDataAnnotation ? ConfigurationSource.DataAnnotation : ConfigurationSource.Convention);
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    bool IConventionPropertyBuilder.CanSetSentinel(object? sentinel, bool fromDataAnnotation)
+        => CanSetSentinel(sentinel, fromDataAnnotation ? ConfigurationSource.DataAnnotation : ConfigurationSource.Convention);
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in

src/EFCore/Metadata/Internal/PropertyConfiguration.cs

@@ -46,23 +46,21 @@ public virtual void Apply(IMutableProperty property)
             {
                 case CoreAnnotationNames.MaxLength:
                     property.SetMaxLength((int?)annotation.Value);
-
+                    break;
+                case CoreAnnotationNames.Sentinel:
+                    property.Sentinel = annotation.Value;
                     break;
                 case CoreAnnotationNames.Unicode:
                     property.SetIsUnicode((bool?)annotation.Value);
-
                     break;
                 case CoreAnnotationNames.Precision:
                     property.SetPrecision((int?)annotation.Value);
-
                     break;
                 case CoreAnnotationNames.Scale:
                     property.SetScale((int?)annotation.Value);
-
                     break;
                 case CoreAnnotationNames.ProviderClrType:
                     property.SetProviderClrType((Type?)annotation.Value);
-
                     break;
                 case CoreAnnotationNames.ValueConverterType:
                     if (ClrType.UnwrapNullableType() == property.ClrType.UnwrapNullableType())
@@ -121,6 +119,24 @@ public virtual void SetMaxLength(int? maxLength)
         this[CoreAnnotationNames.MaxLength] = maxLength;
     }
 
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual int? GetSentinel()
+        => (int?)this[CoreAnnotationNames.Sentinel];
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual void SetSentinel(object? sentinel)
+        => this[CoreAnnotationNames.Sentinel] = sentinel;
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in

test/EFCore.SqlServer.FunctionalTests/GraphUpdates/GraphUpdatesSqlServerOwnedTest.cs

@@ -565,7 +565,7 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
             modelBuilder.Entity<CruiserWithSentinel>(
                 b =>
                 {
-                    b.Property(e => e.IdUserState).HasDefaultValue(1).Metadata.Sentinel = 667;
+                    b.Property(e => e.IdUserState).HasDefaultValue(1).HasSentinel(667);
                     b.HasOne(e => e.UserState).WithMany(e => e.Users).HasForeignKey(e => e.IdUserState);
                 });
         }

test/EFCore.SqlServer.FunctionalTests/GraphUpdates/GraphUpdatesSqlServerTestBase.cs

@@ -53,7 +53,7 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
             modelBuilder.Entity<CruiserWithSentinel>(
                 b =>
                 {
-                    b.Property(e => e.IdUserState).HasDefaultValue(1).Metadata.Sentinel = 667;
+                    b.Property(e => e.IdUserState).HasDefaultValue(1).HasSentinel(667);
                     b.HasOne(e => e.UserState).WithMany(e => e.Users).HasForeignKey(e => e.IdUserState);
                 });
 

test/EFCore.SqlServer.FunctionalTests/SqlServerSentinelValueGenerationScenariosTest.cs

@@ -51,12 +51,12 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
         modelBuilder.Entity<Blog>(
             b =>
             {
-                b.Property(e => e.Id).Metadata.Sentinel = IntSentinel;
-                b.Property(e => e.Name).Metadata.Sentinel = StringSentinel;
-                b.Property(e => e.CreatedOn).Metadata.Sentinel = DateTimeSentinel;
-                b.Property(e => e.GeometryCollection).Metadata.Sentinel = GeometryCollectionSentinel;
-                b.Property(e => e.OtherId).Metadata.Sentinel = NullableIntSentinel;
-                b.Property(e => e.NeedsConverter).Metadata.Sentinel = new NeedsConverter(IntSentinel);
+                b.Property(e => e.Id).HasSentinel(IntSentinel);
+                b.Property(e => e.Name).HasSentinel(StringSentinel);
+                b.Property(e => e.CreatedOn).HasSentinel(DateTimeSentinel);
+                b.Property(e => e.GeometryCollection).HasSentinel(GeometryCollectionSentinel);
+                b.Property(e => e.OtherId).HasSentinel(NullableIntSentinel);
+                b.Property(e => e.NeedsConverter).HasSentinel(new NeedsConverter(IntSentinel));
             });
     }
 }