11# frozen_string_literal: true
22
3- require_relative 'reducer/reduction '
3+ require_relative 'reducer/refinements '
44require_relative 'reducer/middleware'
5- require_relative 'reducer/warnings'
65
76module Rack
8- # Declaratively filter data via URL params, in any Rack app.
9- module Reducer
10- # Create a Reduction object that can filter +dataset+ via +#apply+.
7+ # Declaratively filter data via URL params, in any Rack app, with any ORM.
8+ class Reducer
9+ using Refinements
10+
11+ class << self
12+ # make ::create an alias of ::new, for compatibility with v1
13+ alias create new
14+
15+ # Call Rack::Reducer as a function instead of creating a named reducer
16+ def call ( params , dataset :, filters :)
17+ new ( dataset , *filters ) . apply ( params )
18+ end
19+ end
20+
21+ # Instantiate a Reducer that can filter `dataset` via `#apply`.
1122 # @param [Object] dataset an ActiveRecord::Relation, Sequel::Dataset,
1223 # or other class with chainable methods
1324 # @param [Array<Proc>] filters An array of lambdas whose keyword arguments
1425 # name the URL params you will use as filters
15- # @return Rack::Reducer::Reduction
1626 # @example Create a reducer and use it in a Sinatra app
1727 # DB = Sequel.connect(ENV['DATABASE_URL'])
18- # MyReducer = Rack::Reducer.create(
28+ #
29+ # MyReducer = Rack::Reducer.new(
1930 # DB[:artists],
2031 # lambda { |name:| where(name: name) },
2132 # lambda { |genre:| where(genre: genre) },
@@ -25,63 +36,47 @@ module Reducer
2536 # @artists = MyReducer.apply(params)
2637 # @artists.to_json
2738 # end
28- def self . create ( dataset , *filters )
29- Reduction . new ( dataset , *filters )
39+ def initialize ( dataset , *filters )
40+ @dataset = dataset
41+ @filters = filters
42+ @default_filters = filters . select do |filter |
43+ filter . required_argument_names . empty?
44+ end
3045 end
3146
32- # Filter a dataset without creating a Reducer first.
33- # Note that this approach is a bit slower and less memory-efficient than
34- # creating a Reducer via ::create. Use ::create when you can.
35- #
36- # @param params [Hash] Rack-compatible URL params
37- # @param dataset [Object] A dataset, e.g. one of your App's models
38- # @param filters [Array<Proc>] An array of lambdas with keyword arguments
39- # @example Call Rack::Reducer as a function in a Sinatra app
40- # get '/artists' do
41- # @artists = Rack::Reducer.call(params, dataset: Artist.all, filters: [
42- # lambda { |name:| where(name: name) },
43- # lambda { |genre:| where(genre: genre) },
44- # ])
45- # end
46- def self . call ( params , dataset :, filters :)
47- Reduction . new ( dataset , *filters ) . apply ( params )
48- end
47+ # Run `@filters` against `url_params`
48+ # @param [Hash, ActionController::Parameters, nil] url_params
49+ # a Rack-compatible params hash
50+ # @return `@dataset` with the matching filters applied
51+ def apply ( url_params )
52+ if url_params . empty?
53+ # Return early with the unfiltered dataset if no default filters exist
54+ return @dataset if @default_filters . empty?
55+
56+ # Run only the default filters
57+ filters , params = @default_filters , EMPTY_PARAMS
58+ else
59+ # This request really does want filtering; run a full reduction
60+ filters , params = @filters , url_params . to_unsafe_h . symbolize_keys
61+ end
4962
50- # Mount Rack::Reducer as middleware
51- # @deprecated
52- # Rack::Reducer.new will become an alias of ::create in v2.0.
53- # To mount middleware that will still work in 2.0, write
54- # "use Rack::Reducer::Middleware" instead of "use Rack::Reducer"
55- def self . new ( app , options = { } )
56- warn "#{ caller ( 1 ..1 ) . first } \n #{ Warnings [ :new ] }
57- Middleware . new ( app , options )
63+ reduce ( params , filters )
5864 end
5965
60- # Extend Rack::Reducer to get +reduce+ and +reduces+ as class-methods
61- #
62- # @example Make an "Artists" model reducible
63- # class Artist < SomeORM::Model
64- # extend Rack::Reducer
65- # reduces self.all, filters: [
66- # lambda { |name:| where(name: name) },
67- # lambda { |genre:| where(genre: genre) },
68- # ]
69- # end
70- # Artist.reduce(params)
71- #
72- # @deprecated
73- # Rack::Reducer's mixin-style is deprecated and may be removed in 2.0.
74- # To keep using Rack::Reducer in your models, create a Reducer constant.
75- # class MyModel < ActiveRecord::Base
76- # MyReducer = Rack::Reducer.create(dataset, *filter_functions)
77- # end
78- # MyModel::MyReducer.call(params)
79- def reduces ( dataset , filters :)
80- warn "#{ caller ( 1 ..1 ) . first } \n #{ Warnings [ :reduces ] }
81- reducer = Reduction . new ( dataset , *filters )
82- define_singleton_method :reduce do |params |
83- reducer . apply ( params )
66+ private
67+
68+ def reduce ( params , filters )
69+ filters . reduce ( @dataset ) do |data , filter |
70+ next data unless filter . satisfies? ( params )
71+
72+ data . instance_exec (
73+ **params . slice ( *filter . all_argument_names ) ,
74+ &filter
75+ )
8476 end
8577 end
78+
79+ EMPTY_PARAMS = { } . freeze
80+ private_constant :EMPTY_PARAMS
8681 end
8782end
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