Fixed issue causing explicit null FK's in insert statement to be ignored

DataDude.Tests/Core/Scripts/Migrations/1.0.0/01.Schema.sql

@@ -69,6 +69,13 @@ CREATE TABLE Test_PK_Sequential_Uuid(
 )
 GO
 
+CREATE TABLE Test_Nullable_FK(
+	Id INT PRIMARY KEY,
+	OfficeId INT NULL,
+	CONSTRAINT FK_Test_Nullable_FK_Office FOREIGN KEY (OfficeId) references Buildings.Office(Id),
+)
+GO
+
 CREATE TRIGGER People.EmployeeUpdatedAt ON People.Employee AFTER UPDATE AS BEGIN
 	UPDATE People.Employee 
 		SET People.Employee.UpdatedAt = GETDATE()

DataDude.Tests/Inserts/InstructionTests.cs

@@ -255,5 +255,23 @@ public async Task Can_Insert_Sequential_Default_Using_Generated_Value_Instead_Of
             var rows = await connection.QueryFirstAsync<int>("SELECT Count(1) FROM Test_PK_Sequential_Uuid");
             rows.ShouldBe(1);
         }
+
+        [Fact]
+        public async Task Can_Honor_Specified_Null_Values_When_Inserting_Nullable_FK()
+        {
+            using var connection = Fixture.CreateNewConnection();
+
+            await new Dude()
+                .EnableAutomaticForeignKeys()
+                .Insert("Office", new { Id = 1 })
+                .Insert("Test_Nullable_FK", new { Id = 1 })
+                .Insert("Test_Nullable_FK", new { Id = 2, OfficeId = (int?)null })
+                .Go(connection);
+
+            var firstOfficeId = await connection.QuerySingleAsync<int?>("SELECT OfficeId FROM Test_Nullable_FK WHERE Id = 1");
+            var secondOfficeId = await connection.QuerySingleAsync<int?>("SELECT OfficeId FROM Test_Nullable_FK WHERE Id = 2");
+            firstOfficeId.ShouldBe(1);
+            secondOfficeId.ShouldBeNull();
+        }
     }
 }

DataDude/DataDudeContext.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Data;
 using System.Threading.Tasks;
 using DataDude.Instructions;
@@ -24,6 +25,27 @@ public DataDudeContext(ISchemaLoader schemaLoader)
             InstructionPreProcessors = new List<IInstructionPreProcessor>();
         }
 
+        public static IDictionary<string, DbType> TypeMappings { get; } = new Dictionary<string, DbType>
+        {
+            ["bit"] = DbType.Boolean,
+            ["date"] = DbType.Date,
+            ["datetime"] = DbType.DateTime,
+            ["datetime2"] = DbType.DateTime2,
+            ["datetimeoffset"] = DbType.DateTimeOffset,
+            ["decimal"] = DbType.Decimal,
+            ["numeric"] = DbType.Decimal,
+            ["float"] = DbType.Double,
+            ["uniqueidentifier"] = DbType.Guid,
+            ["smallint"] = DbType.Int16,
+            ["int"] = DbType.Int32,
+            ["bigint"] = DbType.Int64,
+            ["variant"] = DbType.Object,
+            ["varbinary"] = DbType.Binary,
+            ["varchar"] = DbType.String,
+            ["nvarchar"] = DbType.String,
+            ["geography"] = DbType.String,
+        };
+
         public ISchemaLoader SchemaLoader { get; }
 
         public IList<IInstruction> Instructions { get; }
@@ -34,6 +56,16 @@ public DataDudeContext(ISchemaLoader schemaLoader)
 
         public SchemaInformation? Schema { get; private set; }
 
+        public static DbType GetDbType(ColumnInformation column)
+        {
+            if (TypeMappings.ContainsKey(column.DataType))
+            {
+                return TypeMappings[column.DataType];
+            }
+
+            throw new NotImplementedException($"Db type for {column.DataType} of column {column.Table.FullName}.{column.Name} is not known");
+        }
+
         public T? Get<T>(string key)
         {
             if (_store.TryGetValue(key, out var value) && value is T typedValue)

DataDude/Instructions/Insert/InsertData.cs

@@ -14,9 +14,16 @@ public InsertData(TableInformation table, InsertInstruction instruction)
 
             foreach (var column in table)
             {
-                if (instruction.ColumnValues.TryGetValue(column.Name, out var value) && value is { })
+                if (instruction.ColumnValues.ContainsKey(column.Name))
                 {
-                    _data.Add(column, new ColumnValue(value));
+                    if (instruction.ColumnValues[column.Name] is { } value)
+                    {
+                        _data.Add(column, new ColumnValue(value));
+                    }
+                    else
+                    {
+                        _data.Add(column, ColumnValue.Null(DataDudeContext.GetDbType(column)));
+                    }
                 }
                 else
                 {

DataDude/Instructions/Insert/ValueProviders/ValueProvider.cs

@@ -20,7 +20,7 @@ public void Process(ColumnInformation column, ColumnValue value)
             }
             else if (column.IsNullable)
             {
-                value.Set(ColumnValue.Null(GetNullDbType(column.DataType)));
+                value.Set(ColumnValue.Null(DataDudeContext.GetDbType(column)));
             }
             else if (GetDefaultValue(column, value) is { } newValue)
             {
@@ -29,24 +29,5 @@ public void Process(ColumnInformation column, ColumnValue value)
         }
 
         protected abstract ColumnValue? GetDefaultValue(ColumnInformation column, ColumnValue value);
-
-        private DbType GetNullDbType(string dataType) => dataType switch
-        {
-            "bit" => DbType.Boolean,
-            "date" => DbType.Date,
-            "datetime" => DbType.DateTime,
-            "datetime2" => DbType.DateTime2,
-            "datetimeoffset" => DbType.DateTimeOffset,
-            "decimal" or "numeric" => DbType.Decimal,
-            "float" => DbType.Double,
-            "uniqueidentifier" => DbType.Guid,
-            "smallint" => DbType.Int16,
-            "int" => DbType.Int32,
-            "bigint" => DbType.Int64,
-            "variant" => DbType.Object,
-            "varbinary" => DbType.Binary,
-            "varchar" or "nvarchar" or "geography" => DbType.String,
-            _ => throw new NotImplementedException($"Db type for {dataType} is not known"),
-        };
     }
 }