ToOne<EntityT> class

A to-one relation of an entity that references one object of a "target" entity EntityT.

Example:

@Entity()
class Order {
  final customer = ToOne<Customer>();
}

Uses lazy initialization. The target object is only read from the database when it is first accessed.

Common usage:

  • set the target object to create a relation. When the object with the ToOne is put, if the target object is new (its ID is 0), it will be put as well. Otherwise, only the target ID in the database is updated.
  • set the targetId of the target object to create a relation.
  • set target to null or targetId to 0 to remove the relation.

Then, to persist the changes Box.put the object with the ToOne.

// Example 1: create a relation
order.customer.target = customer;
// or order.customer.targetId = customerId;
store.box<Order>().put(order);

// Example 2: remove the relation
order.customer.target = null
// or order.customer.targetId = 0
store.box<Order>().put(order);

The target object is referenced by its ID. This targetId is persisted as part of the object with the ToOne in a special property created for each ToOne (named like "customerId").

To get all objects with a ToOne that reference a target object, see Backlink.

Constructors

ToOne.new({EntityT? target, int? targetId})
Create a ToOne relationship.

Properties

hashCode → int
The hash code for this object.
no setterinherited
hasValue → bool
Whether the relation field has a value stored. Otherwise it's null.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
target ↔ EntityT?
Returns the target object or null if there is none.
getter/setter pair
targetId ↔ int
Get ID of a relation target object.
getter/setter pair

Methods

attach(Store store) → void
Initializes this relation, attaching it to the store.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited