82 lines
2.3 KiB
Ruby
82 lines
2.3 KiB
Ruby
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# frozen_string_literal: true
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module WhereComposite
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extend ActiveSupport::Concern
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class TooManyIds < ArgumentError
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LIMIT = 100
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def initialize(no_of_ids)
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super(<<~MSG)
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At most #{LIMIT} identifier sets at a time please! Got #{no_of_ids}.
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Have you considered splitting your request into batches?
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MSG
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end
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def self.guard(collection)
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n = collection.size
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return collection if n <= LIMIT
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raise self, n
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end
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end
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class_methods do
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# Apply a set of constraints that function as composite IDs.
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#
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# This is the plural form of the standard ActiveRecord idiom:
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# `where(foo: x, bar: y)`, except it allows multiple pairs of `x` and
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# `y` to be specified, with the semantics that translate to:
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#
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# ```sql
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# WHERE
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# (foo = x_0 AND bar = y_0)
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# OR (foo = x_1 AND bar = y_1)
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# OR ...
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# ```
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#
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# or the equivalent:
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#
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# ```sql
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# WHERE
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# (foo, bar) IN ((x_0, y_0), (x_1, y_1), ...)
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# ```
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#
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# @param permitted_keys [Array<Symbol>] The keys each hash must have. There
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# must be at least one key (but really,
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# it ought to be at least two)
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# @param hashes [Array<#to_h>|#to_h] The constraints. Each parameter must have a
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# value for the keys named in `permitted_keys`
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#
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# e.g.:
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# ```
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# where_composite(%i[foo bar], [{foo: 1, bar: 2}, {foo: 1, bar: 3}])
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# ```
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#
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def where_composite(permitted_keys, hashes)
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raise ArgumentError, 'no permitted_keys' unless permitted_keys.present?
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# accept any hash-like thing, such as Structs
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hashes = TooManyIds.guard(Array.wrap(hashes)).map(&:to_h)
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return none if hashes.empty?
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case permitted_keys.size
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when 1
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key = permitted_keys.first
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where(key => hashes.map { |hash| hash.fetch(key) })
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else
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clauses = hashes.map do |hash|
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permitted_keys.map do |key|
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arel_table[key].eq(hash.fetch(key))
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end.reduce(:and)
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end
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where(clauses.reduce(:or))
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end
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rescue KeyError
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raise ArgumentError, "all arguments must contain #{permitted_keys}"
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end
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end
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end
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