Scopes

Scope provides elegant way to write commonly used query fragments and improve readability of your code. Scope returns a new collection Collection or taint the current Collection.
Let's get an example:
class User
    include Clear::Model
​
    primary_key
​
    column role : String
    column role_level : Int32
    column email : String
    column active : Bool
​
    scope :with_privileges do |level|
        where{ role.in?(%w(superadmin admin)) | (role_level > level) }
    end
    scope(:active){ where(active: true) }
end
​
# Later one:
User.with_privileges(3).each do |x|
    puts "Admin #{x.id} - #{x.email}"
end
Scope can be easily chained and you can pass argument to them too:
User.with_admin_privileges(4).active
Scope live both in Model::Collection and Model code space, meaning you may ignore Model.query to start a new Collection but instead go straight to Model.scope.

Window and CTE

Next - Querying

Writing low-level SQL

Last modified 3yr ago

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