ohm-sorted
Sorted indices for Ohm
Setup
-
Include the
Callbacks
andSorted
modules in your model:include Ohm::Callbacks include Ohm::Sorted
-
Add the sorted indices you want to your model:
-
If you want a complete index:
sorted :created_at
-
If you want to partition the index based on an attribute:
sorted :created_at, :group_by => :site_id
You can use both indices for the same attribute, as the partition keys are
namespaced by the group_by
attribute.
You will need to resave every model if they already exist for the index to get built.
The ranking attribute must be of a type that responds to to_f
.
Usage
To query the sorted index, use the sorted_find
class method.
>> Post.sorted_find(:created_at, site_id: "ar")
This returns an Ohm::SortedSet
, similiar to an Ohm::Set
but backed by a sorted
set.
To limit the results to a certain score range, use the between
method.
This and the following methods return a new copy of the set object, but data
is not read until it is necessary.
>> Post.sorted_find(:created_at, site_id: "ar").between(start_time, end_time)
To take a slice of the results, use the slice
method. This returns a new copy
of the set which will pass its offset
and count
parameters to Redis.
>> Post.sorted_find(:created_at, site_id: "ar").slice(2, 4)
Requirements
This plugin works with Ohm versions higher than 0.1.3.
Acknowledgements
Many thanks to Damian Janowski (https://github.com/djanowski)