DraftItem

A DraftItem is the representation of an instance of a Pattern, Element/Collection or Attribute.

It represents an abstraction of both the current state (eg. value of) plus the Schema information about the item.

Schema

The structure of any DraftItem must comply with the schema of the pattern that underpins it. Every DraftItem has a schema underpinning it.

The underpinning schema is defined as either: Pattern, Element, or Attribute defined by the Toolkit that creates the Draft.

For DraftItems, we further expand the set of possible types (based on some common behaviours) to include: DraftCollection.

DraftPattern

A DraftItem that represents a Pattern

• There must be one and only one instance of it (essentially Cardinality=One)
• It behaves just like any other Element apart from the fact that it cannot be deleted (unmaterialised).
• It is always materialised when a draft is created (AutoCreate =true).
• It has no Parent

DraftElement

A DraftItem that represents an Element, where Element.Cardinality=One or ZeroOrOne

• There can be at most one instance of it (determined by Element.Cardinality)
• It can have one or more properties (DraftAttributes), in its collection of Properties

• It can have any number of child DraftElement or DraftCollection, also in its collection of Properties

• It can be deleted (unmaterialised).

• It must have a Parent, and that parent DraftItem is the representation of the logical parent defined in the PatternDefinition

DraftCollection

A DraftItem that represents an Element, where Element.Cardinality=ZeroOrMany or OneOrMany.

Also known as an "Ephemeral Collection", since it has no Value (or Properties).

• There can be at most one instance of it (essentially Cardinality=One or ZeroOrOne)
• It has ZeroOrMany or OneOrMany "Collection Items", in its collection of Items
  • Each "Collection Item" is itself a DraftElement or DraftCollection, which adopts the schema of the underlying Element of this DraftCollection.
• It cannot have any child (DraftAttributes), in its collection of Properties
• It cannot have any child DraftElement or DraftCollection, in its collection of Properties
• It can be deleted (unmaterialised).
• It must have a Parent, and that parent DraftItem is the representation of the logical parent defined in the PatternDefinition

DraftCollectionItem

A DraftItem that represents a DraftElement or DraftCollection that is in the Items collection of another DraftCollection.

• It must have a Parent, and that parent DraftItem is not the containing DraftCollection, but the next ancestor that is not a DraftCollection. It has an ImmediateParent that is the containing DraftCollection.

DraftAttribute

A DraftItem that represents an Attribute.

• There can be at most one instance of it
• It cannot have any "Collection Items" in its collection on Items
• It cannot have any child (DraftAttributes), in its collection of Properties
• It cannot have any child DraftElement or DraftCollection, in its collection of Properties
• It cannot be deleted (unmaterialised) independently from its Parent.
• It must have a Parent, and that parent DraftItem is the representation of the logical parent defined in the PatternDefinition

Lifecycle

When a Draft is created, all of its DraftItems for all of its Schema, and all of its descendant schema, is instantiated.

This means that all the leaves of the initial tree (with the DraftItem as the root) are built initially.

This is done as a strategy to manage the future addition and subtraction of leaves to the tree. In other words, to know (ahead of time) what those leaves could be and where they are on the tree.

In order to keep track of whether an instance is "assigned" we use the notion of "Materialisation".

Only DraftItems for schema that permit creation initially are instantiated. For example, the Pattern, all its Attributes, and any Elements/Collections (and all their attributes) where AutoCreate=true, are created initially. Even though Collections may be created, no items are created.

Materialisation

A DraftItem maintains a state of its own materialisation.

• Materialised, or
• UnMaterialised

Materialised DraftItem:

• A DraftItem has a Value of some sort.
  • That would be a value that the user could "see" and interact with.
    • For example, if you were to view the "Configuration" of the DraftItem, then only materialised Values would be present in the output.
• A DraftItem has a Structure of some sort.
  • For an Attribute, and a ephemeral Collection this is nothing
  • For Pattern/Element/CollectionItem, they will always have materialised Attributes, and descendant Element/Collections.
• The user can view, and interact with anything that is Materialised

UnMaterialised DraftItem:

• The Value will always null
• All structure of the current Pattern/Attribute/Element/Collection/CollectionItem is also UnMaterialised.
• For Collections, their Items are always cleared.
• The user cannot view or interact with anything that is UnMaterialised