76 lines
1.6 KiB
Ruby
76 lines
1.6 KiB
Ruby
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# frozen_string_literal: true
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module AceOfBase
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# A query builder for querying our data.
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class Query
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INVALID_FIELD_MESSAGE = 'Field %s is not a valid field name'
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def initialize(storage)
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@fields = []
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@order_bys = []
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@filters = []
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@storage = storage
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end
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def select(*fields)
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ensure_valid_fields!(fields)
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@fields = fields
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self
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end
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def order_by(*fields)
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ensure_valid_fields!(fields)
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@order_bys = fields
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self
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end
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def filter(field, value)
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ensure_valid_fields!([field])
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@filters << [field, value]
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self
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end
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def execute
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@storage
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.select(&method(:select_with_filters))
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.sort(&method(:sort_with_order_bys))
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.map(&method(:take_fields))
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end
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private
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attr_reader :fields, :order_bys, :filters, :storage
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def ensure_valid_fields!(fields)
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fields.each do |field|
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raise ArgumentError, format(INVALID_FIELD_MESSAGE, field) \
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unless Record::ATTRIBUTES.include?(field.to_sym)
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end
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end
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def take_fields(record)
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selected_fields.map { |field| record.public_send(field) }
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end
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def sort_with_order_bys(lhs, rhs)
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@order_bys
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.lazy
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.map { |attr| lhs.public_send(attr) <=> rhs.public_send(attr) }
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.find(-> { 0 }, &:nonzero?)
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end
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def select_with_filters(record)
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@filters.all? do |(key, value)|
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record.public_send(key) == value
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end
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end
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def selected_fields
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return Record::ATTRIBUTES if fields.empty?
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fields
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end
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end
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end
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