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Metadata Plus

This topic describes Metadata Plus (MDP) 2.0, which is the underlying default storage engine for purchase orders and subscriptions in Optimizely Commerce Cloud.

How it works

MDP lets you extend any system object with a series of meta-fields. It is similar to object-oriented programming. For example, in object-oriented programming, you can create a base Order class, and then a Purchase Order Type object called PurchaseOrder, which inherits its properties and adds specific fields.

The root meta-class is based on a database table called system meta-class. Consider that an abstract meta-class which you must extend to use when associating extended new attributes with a new meta-class. Order becomes a system meta-class, and PurchaseOrder becomes a meta-class that you can extend.

The instance of the meta-class that holds values is called meta-object.

NameDescription
BinaryMSSQL Common Type
BitMSSQL Common Type
CharMSSQL Common Type
DateTimeMSSQL Common Type
DecimalMSSQL Common Type
FloatMSSQL Common Type
ImageMSSQL Common Type
IntMSSQL Common Type
MoneyMSSQL Common Type
NCharMSSQL Common Type
NTextMSSQL Common Type
NVarCharMSSQL Common Type
RealMSSQL Common Type
UniqueIdentifierMSSQL Common Type
SmallDateTimeMSSQL Common Type
SmallIntMSSQL Common Type
SmallMoneyMSSQL Common Type
TextMSSQL Common Type
TimestampMSSQL Common Type
TinyIntMSSQL Common Type
VarBinaryMSSQL Common Type
VarCharMSSQL Common Type
VariantMSSQL Common Type
NumericMSSQL Common Type
SysnameMSSQL Common Type
IntegerMetadata Type
BooleanMetadata Type
DateMetadata Type
EmailMetadata Type
URLMetadata Type
ShortStringMetadata Type
LongStringMetadata Type
LongHtmlStringMetadata Type
DictionarySingleValueMetadata Type
DictionaryMultiValueMetadata Type
EnumSingleValueMetadata Type
EnumMultiValueMetadata Type
StringDictionaryMetadata Type
FileMetadata Type
ImageFileMetadata Type
MetaObjectMetadata Type

Not all properties have a visual designer associated with them, but you can use all of them to extend the meta-class.

The MDP is designed to give the resulting database structure the fastest performance. When a meta-class is created, the container data table and history tables are created with a corresponding set of stored procedures and full text indexes (if full text functionality is enabled). The appropriate indexes are also put.

Meta data fields and classes

Meta-fields

Meta-fields describe different properties associated with an element inside Optimizely Commerce. You can create a meta-field of any type supported by Metadata Plus.

Meta-classes

Optimizely Commerce uses meta-classes to describe different types of elements, such as Categories and Products, that are used in the creation and extension of the Commerce solutions developed. Meta-class is a collection of meta-fields. The following types of meta-classes are defined:

  • Mediachase.MetaDataPlus.System. Used for the built-in OrderGroup elements of Commerce.
  • Mediachase.MetaDataPlus.User. Created when a user defines a new meta-class for a OrderGroup. It is always an extension of one the existing System meta-classes.

Using meta-classes and meta-fields

It is important to understand the concepts of a meta-class and meta-field, which form the basis for Categories and Products, to fully understand how they work within Episerver Commerce. For a better understanding of meta-fields and meta-classes, consider an example of creating a product Book. Book has the following properties:

  • Name
  • ISBN
  • Author
  • Price

To duplicate this product inside your solution, create a BookClass meta-class with the Entry meta-class as its parent. In this example, BookClass is of type Mediachase.MetaDataPlus.User, and the built-in Product meta-class is of type Mediachase.MetaDataPlus.System. 

Next, assign the properties of Book to your BookClass by creating a meta-attribute for each Property, then assigning them to your BookClass. For example, the Name property could be a meta-attribute of type ShortString, and Price can be a meta-attribute of type int. After you create these meta-attributes, assign them to your BookClass.


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