Object Serialization

Sometimes you want a sub-object to be serialized into a string column. Like this:

public class GiftPack
{
	public int ID;

	public Glass Glass;
}

public class Glass
{
	public int Size;
	public string Style;
}

CREATE TABLE GiftPack
AS
	ID int IDENTITY,
	Style [varchar](MAX)
GO

Here, we want to put the class into the Style column and we want it serialized as a string. Now, if the column is an XML column, Insight will automatically use the DataContractSerializer to pack up your object. Here we have a string, so Insight can't do it automatically. We can give it a clue with a column attribute:

public class GiftPack
{
	public int ID;

	[Column(SerializationMode=SerializationMode.Json)]
	public Glass Glass;
}

By adding the Column attribute, we tell Insight to convert the GiftPack to JSON when storing it, and to convert it back when reading it from a recordset. There are several built-in serialization modes:

• Default - see ToString
• Xml - the DataContractSerializer is used to convert to/from XML
• Json - the DataContractJsonSerializer is used to convert to/from XML
• ToString - the ToString method is used to convert the object to a string. An error occurs when reading the object.
• Custom - see Custom Serializers below.

Note that object serialization only occurs when a field is matched to a string column.

Using Mapping Rules to Control Serialization

If you don't like adding attributes to your objects, you can also set up mapping rules to control the serialization formats:

// specify serialization by type and field name
DbSerializationRule.Serialize<GiftPack>("Glass", SerializationMode.Xml);

// specify serialization by type and field type (applies to all fields of the type)
DbSerializationRule.Serialize<GiftPack>(typeof(Glass), SerializationMode.Xml);

// specify serialization by field type (applies across all types/tables) 
DbSerializationRule.Serialize<Glass>(SerializationMode.Xml);

Using JSON.NET for JSON Serialization

If you think DataContractJsonSerializer is slow, and you would rather use Newtonsoft's JSON.NET, you can:

1. Install the Insight.Database.Json package.
2. In your startup code, call Insight.Database.Json.JsonNetObjectSerializer.Initialize()

Then Insight will use the JSON.NET serializer for JSON conversions.

Boolean Serializers

Since a lot of databases don't have a bit type (e.g. Oracle), you might need to convert boolean values to things like "T" and "F". Starting in v5.2, you get a few built-in boolean serializers:

• BooleanYNSerializer
• BooleanTFSerializer
• BooleanTrueFalseSerializer
• Boolean10Serializer
• BooleanSerializer - roll your own like new BooleanSerializer(DbType.String, "Foo", "Bar")

You can install them with any of the methods, including globally like this:

	DbSerializationRule.Serialize<bool>(new BooleanYNSerializer());

Or for a specific field:

DbSerializationRule.Serialize<MyClass>("MyField", new BooleanYNSerializer());

Or with an attribute:

public class MyClass
{
	[Column(SerializationMode=SerializationMode.Custom, Serializer=typeof(Boolean10Serializer))]
	public bool MyField;
}

Custom Serializers

If you have a need for custom serialization, you can create your own object serializer:

public class MyDbObjectSerializer : DbObjectSerializer
{
        public override bool CanSerialize(Type type, DbType dbType)
        {
            return type == typeof(MyDbObject);
        }

        public override bool CanDeserialize(Type sourceType, Type targetType)
        {
            return targetType == typeof(MyDbObject);
        }

	public override object SerializeObject(Type type, object o)
	{
	    return object.ConvertToString();
	}

	public override object DeserializeObject(Type type, object encoded)
	{
            return encoded.ConvertToObject();
	}
}

It's also possible to do a binary serializer by overriding additional methods.

Now, you can just add a Column attribute to your field:

public class GiftPack
{
	public int ID;

	[Column(SerializationMode=SerializationMode.Custom, Serializer=typeof(MyDbObjectSerializer))]
	public Glass Glass;
}

Custom Serializer Rules

If you want to override the way Insight picks serializers:

public class MyDbSerializationRule : IDbSerializationRule
{
	public IDbObjectSerializer GetSerializer(Type recordType, Type memberType, string memberName)
	{
		return MyDbObjectSerializer;
	}
}

DbSerializationRule.AddRule(new MyDbSerializationRule());