Add Named Default Constraints docs (#5035)

Author: AndriySvyryd

entity-framework/core/modeling/generated-properties.md

@@ -2,7 +2,7 @@
 title: Generated Values - EF Core
 description: How to configure value generation for properties when using Entity Framework Core
 author: AndriySvyryd
-ms.date: 1/10/2021
+ms.date: 5/27/2025
 uid: core/modeling/generated-properties
 ---
 
@@ -16,11 +16,28 @@ On relational databases, a column can be configured with a default value; if a r
 
 You can configure a default value on a property:
 
-[!code-csharp[Main](../../../samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValue.cs?name=DefaultValue&highlight=5)]
+[!code-csharp[Main](../../../samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValue.cs?name=DefaultValue&highlight=3)]
 
 You can also specify a SQL fragment that is used to calculate the default value:
 
-[!code-csharp[Main](../../../samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValueSql.cs?name=DefaultValueSql&highlight=5)]
+[!code-csharp[Main](../../../samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValueSql.cs?name=DefaultValueSql&highlight=3)]
+
+Starting with EF 10, for SQL Server you can explicitly specify the name for default value constraints, giving you more control over your database schema.
+
+[!code-csharp[Main](../../../samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValue.cs?name=DefaultValueNamed&highlight=3)]
+
+[!code-csharp[Main](../../../samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValueSql.cs?name=DefaultValueSqlNamed&highlight=3)]
+
+You can also call `UseNamedDefaultConstraints` to enable automatic naming of all the default constraints. Note that if you have existing migrations then the next migration you add will rename every single default constraint in your model.
+
+```C#
+protected override void OnModelCreating(ModelBuilder modelBuilder)
+{
+    modelBuilder
+        .UseNamedDefaultConstraints();
+}
+
+```
 
 ## Computed columns
 

entity-framework/core/what-is-new/ef-core-10.0/whatsnew.md

@@ -185,6 +185,39 @@ await context.Blogs.ExecuteUpdateAsync(s =>
 
 Thanks to [@aradalvand](https://github.com/aradalvand) for proposing and pushing for this change (in [#32018](https://github.com/dotnet/efcore/issues/32018)).
 
+<a name="default-constrain-names"></a>
+
+## Custom Default Constraint Names
+
+In previous versions of EF Core, when you specified a default value for a property, EF Core would always let the database automatically generate a constraint name. Now, you can explicitly specify the name for default value constraints for SQL Server, giving you more control over your database schema.
+
+You can now specify a constraint name when defining default values in your model configuration:
+
+```C#
+protected override void OnModelCreating(ModelBuilder modelBuilder)
+{
+    modelBuilder.Entity<Blog>()
+        .Property(b => b.IsActive)
+        .HasDefaultValue(true, "DF_Blog_IsActive");
+
+    modelBuilder.Entity<Post>()
+        .Property(p => b.CreatedDate)
+        .HasDefaultValueSql("GETDATE()", "DF_Post_CreatedDate");
+}
+
+```
+
+You can also call `UseNamedDefaultConstraints` to enable automatic naming of all the default constraints. Note that if you have existing migrations then the next migration you add will rename every single default constraint in your model.
+
+```C#
+protected override void OnModelCreating(ModelBuilder modelBuilder)
+{
+    modelBuilder
+        .UseNamedDefaultConstraints();
+}
+
+```
+
 <a name="other-improvements"></a>
 
 ## Other improvements

samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValue.cs

@@ -6,14 +6,20 @@ internal class MyContext : DbContext
 {
     public DbSet<Blog> Blogs { get; set; }
 
-    #region DefaultValue
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
+        #region DefaultValue
         modelBuilder.Entity<Blog>()
             .Property(b => b.Rating)
             .HasDefaultValue(3);
+        #endregion
+    
+        #region DefaultValueNamed
+        modelBuilder.Entity<Blog>()
+            .Property(b => b.Rating)
+            .HasDefaultValue(3, "DF_Blog_IsActive");
+        #endregion
     }
-    #endregion
 }
 
 public class Blog

samples/core/Modeling/GeneratedProperties/FluentAPI/DefaultValueSql.cs

@@ -7,14 +7,20 @@ internal class MyContext : DbContext
 {
     public DbSet<Blog> Blogs { get; set; }
 
-    #region DefaultValueSql
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
+        #region DefaultValueSql
         modelBuilder.Entity<Blog>()
             .Property(b => b.Created)
             .HasDefaultValueSql("getdate()");
+        #endregion
+
+        #region DefaultValueSqlNamed
+        modelBuilder.Entity<Blog>()
+            .Property(b => b.Created)
+            .HasDefaultValueSql("getdate()" , "DF_Blog_IsActive");
+        #endregion
     }
-    #endregion
 }
 
 public class Blog