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EmberData treats data "opaquely" meaning that any data format will work so long as you are able to describe to the library how that data fits into various concepts (usually this is done by implementing a Cache).
Below, we describe the semantic meaning of these more opaque concepts.
A resource is a unit of discretely identifiable data.
Usually resources map to things like rows in a database with their "type" being derived from the table name.
Discretely identifiable means that given some data, your app would consistently be able to identify the source of that data and meaningfully distinguish it from other data.
For instance, in the following JSON we have two distinct resources:
{
"users": [
{ "id": 1, "name": "Chris" }, // => resource 1
{ "id": 2, "name": "Rey" } // => resource 2
]
}Every resource has a string "type". All resources with the same type are assumed to have the same schema.
Types can represent polymorphic traits.
For instance, imagine your API has the notion of an automobile resource. Automobiles have an id, a number of wheels, and a name.
{
"automobiles": [
{ "id": 1, "wheels": 4, "name": "Rivian R1T" }
]
}However, every specific automobile belongs to a more specialized type. For instance "pickup" which has the additional fields of length and 4wd and "racecar" which has the additional field of topspeed.
{
"pickups": [
{
"id": 1,
"wheels": 4,
"name": "Rivian R1T",
"length": "12ft",
"4wd": true
}
],
"racecars": [
{
"id": 2,
"wheels": 4,
"name": "Mazda 787B",
"topspeed": { "value": 258, "unit": "mph" }
}
]
}In this case, we can refer to both type pickup and type racecar as satisfying type automobile. We refer to pickup and racecar as "concrete types" and to automobile as an abstract type. For more, read about polymorphism in depth.
The "inverse" of a relationship is the compound key generated by considering both the type and the name of the matching field on the related resource .
E.g. if Users have Pets and Pets have Owners, then the
inverse of the field user.pets is pet.owners, and the inverse of pet.owners is similarly user.pets.
Note
to-nonerelationships have no inverse. We often refer to this as anull inverse.
Self referential relationships are relationships that point back at the same resource type.
E.g. if a Person has parents and children, the link between person.parents and person.children is self-referential because both sides belong to the person resource type.
Reflexive relationships are self-referential relationships that point back at the same property in addition to the same type.
For instance, if a User has friends, where user.friends is its own inverse.
A circular relationship is a self-referential or reflexive relationship for which the value is the same on both sides.
For instance, if Ego is his own best friend, then ego.bestFriend === ego
Polymorphic relationships can be satisfied by multiple resource types. For instance, a user may have many vehicles, and each vehicle might be of type car or boat or airplane etc.