Ash has extensive Query support (across DataLayers)!
Zach (Ash’s Author) is clear that he was not interested in recreating something like Active Record. Ash Queries are quite flexible. For now we will start with filters, sort and select. However, there are many Query Functions available – including sort, distinct, aggregate, calculate, limit, offset, subset_of, etc (more or less any Query mechanism needed). The nice thing is that this functions with all Data Layer, ETS, SQL, Mnesia, etc.
To learn more visit:
Critical Query Functions
In order to user Queries we must REQUIRE the Ash.Query macro with: require Ash.Query so an iex session might look like:
require Ash.Query
# a simple 'read' returns ALL users:
Support.AshApi.read!(Support.User)
# don't return duplicate emails
Support.User
|> Ash.Query.new()
|> Ash.Query.distinct(query, :last_name)
|> Support.AshApi.read!()
# we can sort the results with:
Support.User
|> Ash.Query.sort([last_name: :desc, first_name: :asc])
|> Support.AshApi.read!()
# we can limit our results to the first value - with a limit 1
Support.User
|> Ash.Query.sort([last_name: :desc, first_name: :asc])
|> Ash.Query.limit(1)
|> Support.AshApi.read!()
# with filter we can return users with 'Office' within the department_name
Support.User
|> Ash.Query.filter(contains(department_name, "Office"))
|> Support.AshApi.read!()
# we can add multiple filters and build complex filters
Support.User
|> Ash.Query.filter(contains(department_name, "Office"))
|> Ash.Query.filter(account_type == :employee and not(contains(department_name, "Admin")))
|> Support.AshApi.read!()
# we can limit what values are returned with select
Support.User
|> Ash.Query.filter(contains(department_name, "Office"))
|> Ash.Query.filter(account_type == :employee and not(contains(department_name, "Admin")))
|> Ash.Query.sort([last_name: :desc, first_name: :asc])
|> Ash.Query.limit(1)
|> Ash.Query.select([:first_name, :last_name])
|> Support.AshApi.read!()
# notice our return only contains id, first_name and last_name now
[
#Support.User<
__meta__: #Ecto.Schema.Metadata<:loaded>,
id: "23bb05e1-936a-4dc6-94b4-a2123a37eb65",
email: nil,
first_name: "Nyima",
middle_name: nil,
last_name: "Sönam",
admin: nil,
account_type: nil,
department_name: nil,
inserted_at: nil,
updated_at: nil,
aggregates: %{},
calculations: %{},
__order__: nil,
...
>
]