Fix NRE with AlterColumn

Author: mythz

src/ServiceStack.OrmLite/OrmLiteSchemaModifyApi.cs

@@ -15,6 +15,14 @@ public enum OnFkOption
 
     public static class OrmLiteSchemaModifyApi
     {
+        private static void InitUserFieldDefinition(Type modelType, FieldDefinition fieldDef)
+        {
+            if (fieldDef.PropertyInfo == null)
+            {
+                fieldDef.PropertyInfo = TypeProperties.Get(modelType).GetPublicProperty(fieldDef.Name);
+            }
+        }
+
         public static void AlterTable<T>(this IDbConnection dbConn, string command)
         {
             AlterTable(dbConn, typeof(T), command);
@@ -35,6 +43,8 @@ public static void AddColumn<T>(this IDbConnection dbConn, Expression<Func<T, ob
 
         public static void AddColumn(this IDbConnection dbConn, Type modelType, FieldDefinition fieldDef)
         {
+            InitUserFieldDefinition(modelType, fieldDef);
+
             var command = dbConn.GetDialectProvider().ToAddColumnStatement(modelType, fieldDef);
             dbConn.ExecuteSql(command);
         }
@@ -48,6 +58,8 @@ public static void AlterColumn<T>(this IDbConnection dbConn, Expression<Func<T,
 
         public static void AlterColumn(this IDbConnection dbConn, Type modelType, FieldDefinition fieldDef)
         {
+            InitUserFieldDefinition(modelType, fieldDef);
+
             var command = dbConn.GetDialectProvider().ToAlterColumnStatement(modelType, fieldDef);
             dbConn.ExecuteSql(command);
         }

tests/ServiceStack.OrmLite.Tests/Issues/NullReferenceIssues.cs

@@ -0,0 +1,40 @@
+using NUnit.Framework;
+using ServiceStack.Logging;
+
+namespace ServiceStack.OrmLite.Tests.Issues
+{
+    public class NullReferenceIssues : OrmLiteTestBase
+    {
+        public class Foo
+        {
+            public int Id { get; set; }
+
+            public string Name { get; set; }
+
+            public string Key { get; set; }
+        }
+
+        [Test]
+        public void Can_AlterColumn()
+        {
+            if (Dialect == Dialect.Sqlite)
+                return; // Not supported
+
+            LogManager.LogFactory = new ConsoleLogFactory(debugEnabled:true);
+
+            using (var db = OpenDbConnection())
+            {
+                db.DropAndCreateTable<Foo>();
+
+                db.AlterColumn(typeof(Foo), new FieldDefinition
+                {
+                    Name = "Name",
+                    FieldType = typeof(string),
+                    IsNullable = true,
+                    DefaultValue = null
+                });
+            }
+        }
+
+    }
+}