public function __construct(model_relation $relation)
{
if (!$relation) {
throw new \InvalidArgumentException('missing relation');
}
$this->relationName = $relation->getName();
if (is_null($this->relationName)) {
// relation's name is considered equivalent to some property of starting node's model
throw new \InvalidArgumentException('relation must be named for editing');
}
// check if relation's binding makes it suitable for editing here
// (there must be exactly one unbound reference in relation now)
$unboundReferences = $relation->getUnboundReferences();
switch (count($unboundReferences)) {
case 1:
break;
case 2:
if ($unboundReferences[0] === $relation->referenceAtIndex(0)) {
// first reference might be also unbound due to item not
// selected yet
// -> ignore ...
array_shift($unboundReferences);
break;
}
default:
throw new \InvalidArgumentException('relation is not properly bound for editing');
}
// store information
$this->relation = $relation;
$this->mutable = array_shift($unboundReferences);
// also take snapshot of relation's initial binding state
$this->initialBinding = model_relation_binding::createOnRelation($relation)->save();
}
