As mentioned above, the data store manages model data and knows
how to retrieve it. In the previous chapter, you returned data in
the SightingRoute model callback with an array.
In Chapter 22, you will retrieve model data in this route
and return data as a Promise using this.store.findAll
and other data retrieval methods.
Below is a table of methods Ember Data’s store
object has at its disposal for retrieving data from an API,
storing it in memory, and returning it to the requester.
| Request type | Retrieve all records | Retrieve a single record |
|---|---|---|
| find persisted and local records | findAll | findRecord |
| find local records only | peekAll | peekRecord |
| find filtered records | query | queryRecord |
Retrieval methods come in several flavors: persisted and local, local only, and filtered persisted and local. Most use cases call for findAll and findRecord. The arguments for each match closely to the API endpoints that Ember Data will create to request the data from the API.
For findAll, the only required argument is
the model name. For example, a request for all the witnesses would
be findAll('witness'). Notice the singular
name? Remember, this argument is the model name. Ember Data will
make sure the request has a plural name when it builds the Ajax URL
/witnesses/.
For findRecord, an additional argument is
needed to indicate a specific record. This argument is the identifier,
usually the id of the record, such as
this.store.findRecord('witness', 5). When
called, findRecord('witness', 5) will create a
request for data at /witnesses/5.
For peekAll and
peekRecord, the same arguments are needed to
retrieve data. Invoking these methods will return the data
immediately, not as a Promise.
Querying your API for data is another way to form requests. If
your API supports query parameters, or params, for
individual endpoints, Ember Data’s
query and queryRecord
are great options. Like the other
store methods, these methods take the model name as their first argument.
The last argument is the query object, whose key/value pairs are
converted into query string values. For query,
the request will find all records filtered
by keys and values. queryRecord is used when
you know the request will return a single record.
For example, calling
this.store.query('user',{fName: "todd"})
would produce this request: /users/?f_name=todd. Alternatively,
this.store.queryRecord('user', {email: '[email protected]'})
would produce this request: /[email protected].
All of these store methods leverage adapters,
which you will read about in the next chapter.