Support Database Default values specified using a custom attribute #85

#85

Author: jonkeda

SQLite.CodeFirst.Console/Entity/Person.cs

@@ -1,4 +1,6 @@
-using System.ComponentModel.DataAnnotations;
+using System;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
 
 namespace SQLite.CodeFirst.Console.Entity
 {
@@ -18,5 +20,9 @@ public abstract class Person : IEntity
 
         [Required]
         public string City { get; set; }
+
+        [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
+        [SqlDefaultValue(DefaultValue = "DATETIME('now')")]
+        public DateTime CreatedUtc { get; set; }
     }
 }

SQLite.CodeFirst.Console/Program.cs

@@ -131,6 +131,7 @@ private static void DisplaySeededData(DbContext context)
                     System.Console.WriteLine("\t\t LastName: {0}", player.LastName);
                     System.Console.WriteLine("\t\t Street: {0}", player.Street);
                     System.Console.WriteLine("\t\t City: {0}", player.City);
+                    System.Console.WriteLine("\t\t Created: {0}", player.CreatedUtc);
                     System.Console.WriteLine();
                 }
             }

SQLite.CodeFirst.Test/SQLite.CodeFirst.Test.csproj

@@ -98,6 +98,7 @@
     <Compile Include="UnitTests\Statement\ColumnConstraint\ColumnConstraintCollectionTest.cs" />
     <Compile Include="UnitTests\Statement\ColumnConstraint\NotNullConstraintTest.cs" />
     <Compile Include="UnitTests\Statement\ColumnConstraint\CollateConstraintTest.cs" />
+    <Compile Include="UnitTests\Statement\ColumnConstraint\DefaultValueConstraintTest.cs" />
     <Compile Include="UnitTests\Statement\ColumnConstraint\UniqueConstraintTest.cs" />
     <Compile Include="UnitTests\Statement\ColumnStatementCollectionTest.cs" />
     <Compile Include="UnitTests\Statement\PrimaryKeyStatementTest.cs" />

SQLite.CodeFirst.Test/UnitTests/Statement/ColumnConstraint/DefaultValueConstraintTest.cs

@@ -0,0 +1,36 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using SQLite.CodeFirst.Statement.ColumnConstraint;
+
+namespace SQLite.CodeFirst.Test.UnitTests.Statement.ColumnConstraint
+{
+    [TestClass]
+    public class DefaultValueConstraintTest
+    {
+        [TestMethod]
+        public void CreateStatement_StatementIsCorrect_IntDefault()
+        {
+            var defaultValueConstraint = new DefaultValueConstraint();
+            defaultValueConstraint.DefaultValue = "0";
+            string output = defaultValueConstraint.CreateStatement();
+            Assert.AreEqual(output, "DEFAULT 0");
+        }
+
+        [TestMethod]
+        public void CreateStatement_StatementIsCorrect_StringDefault()
+        {
+            var defaultValueConstraint = new DefaultValueConstraint();
+            defaultValueConstraint.DefaultValue = @"'Something'";
+            string output = defaultValueConstraint.CreateStatement();
+            Assert.AreEqual(output, "DEFAULT 'Something'");
+        }
+
+        [TestMethod]
+        public void CreateStatement_StatementIsCorrect_ExpressionDefault()
+        {
+            var defaultValueConstraint = new DefaultValueConstraint();
+            defaultValueConstraint.DefaultValue = @"(datetime('now'))";
+            string output = defaultValueConstraint.CreateStatement();
+            Assert.AreEqual(output, "DEFAULT (datetime('now'))");
+        }
+    }
+}

SQLite.CodeFirst/Internal/Builder/ColumnStatementCollectionBuilder.cs

@@ -41,6 +41,7 @@ private IEnumerable<ColumnStatement> CreateColumnStatements()
                 AddUniqueConstraintIfNecessary(property, columnStatement);
                 AddCollationConstraintIfNecessary(property, columnStatement);
                 AddPrimaryKeyConstraintAndAdjustTypeIfNecessary(property, columnStatement);
+                AddDefaultValueConstraintIfNecessary(property, columnStatement);
 
                 yield return columnStatement;
             }
@@ -90,6 +91,15 @@ private static void AddUniqueConstraintIfNecessary(EdmProperty property, ColumnS
             }
         }
 
+        private static void AddDefaultValueConstraintIfNecessary(EdmProperty property, ColumnStatement columnStatement)
+        {
+            var value = property.GetCustomAnnotation<SqlDefaultValueAttribute>();
+            if (value != null)
+            {
+                columnStatement.ColumnConstraints.Add(new DefaultValueConstraint { DefaultValue = value.DefaultValue });
+            }
+        }
+
         private void AddPrimaryKeyConstraintAndAdjustTypeIfNecessary(EdmProperty property, ColumnStatement columnStatement)
         {
             // Only handle a single primary key this way.

SQLite.CodeFirst/Internal/Statement/ColumnConstraint/DefaultValueConstraint.cs

@@ -0,0 +1,20 @@
+using System.Text;
+
+namespace SQLite.CodeFirst.Statement.ColumnConstraint
+{
+    internal class DefaultValueConstraint : IColumnConstraint
+    {
+        private const string Template = "DEFAULT ({defaultValue})";
+
+        public string DefaultValue { get; set; }
+
+        public string CreateStatement()
+        {
+            var sb = new StringBuilder(Template);
+
+            sb.Replace("{defaultValue}", DefaultValue);
+
+            return sb.ToString().Trim();
+        }
+    }
+}

SQLite.CodeFirst/Public/Attributes/SqlDefaultValueAttribute.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace SQLite.CodeFirst
+{
+    /// <summary>
+    /// Decorate an column with this attribute to create a "DEFAULT {defaultvalue}".
+    /// <remarks>
+    /// https://www.sqlite.org/lang_createtable.html [05.10.2017]
+    /// </remarks>
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Property)]
+    public sealed class SqlDefaultValueAttribute : Attribute
+    {
+        public string DefaultValue { get; set; }
+    }
+}

SQLite.CodeFirst/Public/DbInitializers/SqliteInitializerBase.cs

@@ -43,6 +43,7 @@ protected SqliteInitializerBase(DbModelBuilder modelBuilder)
             modelBuilder.RegisterAttributeAsColumnAnnotation<UniqueAttribute>();
             modelBuilder.RegisterAttributeAsColumnAnnotation<CollateAttribute>();
             modelBuilder.RegisterAttributeAsColumnAnnotation<AutoincrementAttribute>();
+            modelBuilder.RegisterAttributeAsColumnAnnotation<SqlDefaultValueAttribute>();
 
             // By default there is a 'ForeignKeyIndexConvention' but it can be removed.
             // And there is no "Contains" and no way to enumerate the ConventionsCollection.

SQLite.CodeFirst/SQLite.CodeFirst.csproj

@@ -88,13 +88,15 @@
       <Link>Properties\AssemblySharedInfo.cs</Link>
     </Compile>
     <Compile Include="Internal\Builder\NameCreators\NameCreator.cs" />
+    <Compile Include="Internal\Statement\ColumnConstraint\DefaultValueConstraint.cs" />
     <Compile Include="Internal\Utility\InMemoryAwareFile.cs" />
     <Compile Include="Internal\Extensions\ListExtensions.cs" />
     <Compile Include="Internal\Statement\ColumnConstraint\PrimaryKeyConstraint.cs" />
     <Compile Include="Public\Attributes\AutoincrementAttribute.cs" />
     <Compile Include="Public\Attributes\CollateAttribute.cs" />
     <Compile Include="Public\Attributes\CollationFunction.cs" />
     <Compile Include="Public\Attributes\OnConflictAction.cs" />
+    <Compile Include="Public\Attributes\SqlDefaultValueAttribute.cs" />
     <Compile Include="Public\Attributes\UniqueAttribute.cs" />
     <Compile Include="Public\Entities\IHistory.cs" />
     <Compile Include="Internal\Builder\NameCreators\IndexNameCreator.cs" />