Support ON UPDATE CASCADE via CascadeOnUpdate attribute

README.md

@@ -28,14 +28,15 @@ The following features are supported:
 - Tables from classes (supported annotations: `Table`)
 - Columns from properties (supported annotations: `Column`, `Key`, `MaxLength`, `Required`, `NotMapped`, `DatabaseGenerated`, `Index`)
 - PrimaryKey constraint (`Key` annotation, key composites are supported)
-- ForeignKey constraint (1-n relationships, support for 'Cascade on delete')
+- ForeignKey constraint (1-n relationships, support for 'Cascade on delete' and 'Cascade on update')
 - Not Null constraint
 - Auto increment (An int PrimaryKey will automatically be incremented and you can explicitly set the "AUTOINCREMENT" constraint to a PrimaryKey using the Autoincrement-Attribute)
 - Index (Decorate columns with the `Index` attribute. Indices are automatically created for foreign keys by default. To prevent this you can remove the convention `ForeignKeyIndexConvention`)
 - Unique constraint (Decorate columns with the `UniqueAttribute`, which is part of this library)
 - Collate constraint (Decorate columns with the `CollateAttribute`, which is part of this library. Use `CollationFunction.Custom` to specify your own collation function.)
 - Default collation (pass an instance of Collation as constructor parameter for an initializer to specify a default collation).
 - SQL default value (Decorate columns with the `SqlDefaultValueAttribute`, which is part of this library)
+- Cascade on update (Decorate the foreign key property with the `CascadeOnUpdateAttribute`, which is part of this library. Entity Framework cannot express `ON UPDATE CASCADE`, so this opt-in attribute must be placed on the dependent foreign key property, e.g. `TeamId`, not on the navigation property. It requires an explicit foreign key property.)
 
 ## Install
 

SQLite.CodeFirst.Test/IntegrationTests/CascadeOnUpdateTest.cs

@@ -0,0 +1,125 @@
+using System.Collections.Generic;
+using System.Data.Common;
+using System.Data.Entity;
+using System.Data.Entity.Infrastructure;
+using System.Data.SQLite;
+using System.Linq;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace SQLite.CodeFirst.Test.IntegrationTests
+{
+    /// <summary>
+    /// Verifies that the <see cref="CascadeOnUpdateAttribute"/> placed on a foreign key property
+    /// results in 'ON UPDATE CASCADE' being emitted for the corresponding foreign key constraint.
+    /// This exercises the full pipeline: the attribute is registered as a column annotation, survives
+    /// the EF model build and is read back from the store model when the SQL is generated.
+    /// </summary>
+    [TestClass]
+    public class CascadeOnUpdateTest
+    {
+        private static string generatedSql;
+
+        [TestMethod]
+        public void CascadeOnUpdateAttributeEmitsOnUpdateCascade()
+        {
+            using (DbConnection connection = new SQLiteConnection("FullUri=file::memory:"))
+            {
+                // This is important! Else the in memory database will not work.
+                connection.Open();
+
+                using (var context = new CascadeDbContext(connection))
+                {
+                    // Touching the set forces the initializer (and therefore the SQL generation) to run.
+                    context.Set<Order>().FirstOrDefault();
+                }
+            }
+
+            // Decorated FK with cascade-on-delete: both keywords, delete before update.
+            StringAssert.Contains(generatedSql, "FOREIGN KEY ([CustomerId]) REFERENCES \"Customers\"([Id]) ON DELETE CASCADE ON UPDATE CASCADE");
+
+            // Decorated FK without cascade-on-delete: only the update keyword.
+            StringAssert.Contains(generatedSql, "FOREIGN KEY ([WarehouseId]) REFERENCES \"Warehouses\"([Id]) ON UPDATE CASCADE");
+
+            // Undecorated FK: no cascade keyword at all.
+            Assert.IsFalse(generatedSql.Contains("[RegionId]) REFERENCES \"Regions\"([Id]) ON"),
+                "The foreign key without the attribute must not emit any cascade clause.");
+        }
+
+        private class Customer
+        {
+            public int Id { get; set; }
+        }
+
+        private class Warehouse
+        {
+            public int Id { get; set; }
+        }
+
+        private class Region
+        {
+            public int Id { get; set; }
+        }
+
+        private class Order
+        {
+            public int Id { get; set; }
+
+            [CascadeOnUpdate]
+            public int CustomerId { get; set; }
+            public Customer Customer { get; set; }
+
+            [CascadeOnUpdate]
+            public int? WarehouseId { get; set; }
+            public Warehouse Warehouse { get; set; }
+
+            public int? RegionId { get; set; }
+            public Region Region { get; set; }
+        }
+
+        private class CascadeDbContext : DbContext
+        {
+            public CascadeDbContext(DbConnection connection)
+                : base(connection, false)
+            {
+            }
+
+            protected override void OnModelCreating(DbModelBuilder modelBuilder)
+            {
+                modelBuilder.Entity<Order>()
+                    .HasRequired(o => o.Customer)
+                    .WithMany()
+                    .HasForeignKey(o => o.CustomerId)
+                    .WillCascadeOnDelete(true);
+
+                modelBuilder.Entity<Order>()
+                    .HasOptional(o => o.Warehouse)
+                    .WithMany()
+                    .HasForeignKey(o => o.WarehouseId)
+                    .WillCascadeOnDelete(false);
+
+                modelBuilder.Entity<Order>()
+                    .HasOptional(o => o.Region)
+                    .WithMany()
+                    .HasForeignKey(o => o.RegionId)
+                    .WillCascadeOnDelete(false);
+
+                Database.SetInitializer(new CaptureInitializer(modelBuilder));
+            }
+        }
+
+        private class CaptureInitializer : SqliteInitializerBase<CascadeDbContext>
+        {
+            public CaptureInitializer(DbModelBuilder modelBuilder)
+                : base(modelBuilder)
+            {
+            }
+
+            public override void InitializeDatabase(CascadeDbContext context)
+            {
+                DbModel model = ModelBuilder.Build(context.Database.Connection);
+                generatedSql = new SqliteSqlGenerator().Generate(model.StoreModel);
+                base.InitializeDatabase(context);
+            }
+        }
+    }
+}

SQLite.CodeFirst.Test/UnitTests/Statement/ForeignKeyStatementTest.cs

@@ -37,6 +37,37 @@ public void CreateStatementOneForeignKeyCascadeDeleteTest()
             Assert.AreEqual("FOREIGN KEY ([dummyForeignKey1]) REFERENCES dummyForeignTable([dummForeignPrimaryKey1]) ON DELETE CASCADE", output);
         }
 
+        [TestMethod]
+        public void CreateStatementOneForeignKeyCascadeUpdateTest()
+        {
+            var foreignKeyStatement = new ForeignKeyStatement
+            {
+                CascadeUpdate = true,
+                ForeignKey = new List<string> { "dummyForeignKey1" },
+                ForeignPrimaryKey = new List<string> { "dummForeignPrimaryKey1" },
+                ForeignTable = "dummyForeignTable"
+            };
+
+            string output = foreignKeyStatement.CreateStatement();
+            Assert.AreEqual("FOREIGN KEY ([dummyForeignKey1]) REFERENCES dummyForeignTable([dummForeignPrimaryKey1]) ON UPDATE CASCADE", output);
+        }
+
+        [TestMethod]
+        public void CreateStatementOneForeignKeyCascadeDeleteAndUpdateTest()
+        {
+            var foreignKeyStatement = new ForeignKeyStatement
+            {
+                CascadeDelete = true,
+                CascadeUpdate = true,
+                ForeignKey = new List<string> { "dummyForeignKey1" },
+                ForeignPrimaryKey = new List<string> { "dummForeignPrimaryKey1" },
+                ForeignTable = "dummyForeignTable"
+            };
+
+            string output = foreignKeyStatement.CreateStatement();
+            Assert.AreEqual("FOREIGN KEY ([dummyForeignKey1]) REFERENCES dummyForeignTable([dummForeignPrimaryKey1]) ON DELETE CASCADE ON UPDATE CASCADE", output);
+        }
+
         [TestMethod]
         public void CreateStatementTwoForeignKeyTest()
         {

SQLite.CodeFirst/Internal/Builder/ForeignKeyStatementBuilder.cs

@@ -29,7 +29,8 @@ private IEnumerable<ForeignKeyStatement> GetForeignKeyStatements()
                     ForeignKey = associationType.ForeignKey,
                     ForeignTable = associationType.FromTableName,
                     ForeignPrimaryKey = associationType.ForeignPrimaryKey,
-                    CascadeDelete = associationType.CascadeDelete
+                    CascadeDelete = associationType.CascadeDelete,
+                    CascadeUpdate = associationType.CascadeUpdate
                 };
             }
         }

SQLite.CodeFirst/Internal/Statement/ForeignKeyStatement.cs

@@ -9,11 +9,13 @@ internal class ForeignKeyStatement : IStatement
     {
         private const string Template = "FOREIGN KEY ({foreign-key}) REFERENCES {referenced-table}({referenced-id})";
         private const string CascadeDeleteStatement = "ON DELETE CASCADE";
+        private const string CascadeUpdateStatement = "ON UPDATE CASCADE";
 
         public IEnumerable<string> ForeignKey { get; set; }
         public string ForeignTable { get; set; }
         public IEnumerable<string> ForeignPrimaryKey { get; set; }
         public bool CascadeDelete { get; set; }
+        public bool CascadeUpdate { get; set; }
 
         public string CreateStatement()
         {
@@ -25,6 +27,10 @@ public string CreateStatement()
             {
                 sb.Append(" " + CascadeDeleteStatement);
             }
+            if (CascadeUpdate)
+            {
+                sb.Append(" " + CascadeUpdateStatement);
+            }
 
             return sb.ToString();
         }

SQLite.CodeFirst/Internal/Utility/SqliteAssociationType.cs

@@ -2,6 +2,7 @@
 using System.Data.Entity.Core.Metadata.Edm;
 using System.Linq;
 using SQLite.CodeFirst.Builder.NameCreators;
+using SQLite.CodeFirst.Extensions;
 
 namespace SQLite.CodeFirst.Utility
 {
@@ -30,6 +31,13 @@ public SqliteAssociationType(AssociationType associationType, EntityContainer co
             ForeignKey = associationType.Constraint.ToProperties.Select(x => x.Name);
             ForeignPrimaryKey = associationType.Constraint.FromProperties.Select(x => x.Name);
             CascadeDelete = associationType.Constraint.FromRole.DeleteBehavior == OperationAction.Cascade;
+
+            // EF has no notion of update-cascade, so it is opt-in via the CascadeOnUpdateAttribute placed on the
+            // dependent foreign key property. The attribute is registered as a column annotation and therefore
+            // available on the store model foreign key columns (the constraint's ToProperties).
+            CascadeUpdate = associationType.Constraint.ToProperties
+                .Select(property => property.GetCustomAnnotation<CascadeOnUpdateAttribute>())
+                .Any(attribute => attribute != null && attribute.CanCascade);
         }
 
         private static bool IsSelfReferencing(AssociationType associationType)
@@ -47,5 +55,6 @@ private static bool IsSelfReferencing(AssociationType associationType)
         public string ToTableName { get; }
         public IEnumerable<string> ForeignPrimaryKey { get; }
         public bool CascadeDelete { get; }
+        public bool CascadeUpdate { get; }
     }
 }

SQLite.CodeFirst/Public/Attributes/CascadeOnUpdateAttribute.cs

@@ -0,0 +1,28 @@
+using System;
+
+namespace SQLite.CodeFirst
+{
+    /// <summary>
+    /// Adds 'ON UPDATE CASCADE' to the foreign key constraint of the relationship the decorated property belongs to.
+    /// Entity Framework has no concept of update-cascade (it assumes primary keys are immutable), so neither the
+    /// <see cref="System.ComponentModel.DataAnnotations.Schema.ForeignKeyAttribute"/> nor the fluent API can express it.
+    /// This opt-in attribute is the only way to emit the keyword.
+    /// Place it on the dependent foreign key property (e.g. the 'TeamId' property), not on the navigation property (e.g. 'Team').
+    /// Requires an explicit foreign key property; relationships with a shadow foreign key column cannot be decorated.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Property)]
+    public sealed class CascadeOnUpdateAttribute : Attribute
+    {
+        public CascadeOnUpdateAttribute()
+        {
+            CanCascade = true;
+        }
+
+        public CascadeOnUpdateAttribute(bool canCascade)
+        {
+            CanCascade = canCascade;
+        }
+
+        public bool CanCascade { get; }
+    }
+}

SQLite.CodeFirst/Public/DbInitializers/SqliteInitializerBase.cs

@@ -40,6 +40,7 @@ protected SqliteInitializerBase(DbModelBuilder modelBuilder, Collation defaultCo
             modelBuilder.RegisterAttributeAsColumnAnnotation<CollateAttribute>();
             modelBuilder.RegisterAttributeAsColumnAnnotation<AutoincrementAttribute>();
             modelBuilder.RegisterAttributeAsColumnAnnotation<SqlDefaultValueAttribute>();
+            modelBuilder.RegisterAttributeAsColumnAnnotation<CascadeOnUpdateAttribute>();
 
             // By default there is a 'ForeignKeyIndexConvention' but it can be removed.
             // And there is no "Contains" and no way to enumerate the ConventionsCollection.