。在查詢零屬性時返回nil

Question

我試圖通過其屬性使用.where查找對象（Variant），如果沒有參數爲零，查詢將起作用，否則它不返回任何內容。這裏是我的代碼：

product.product_options.blank? ? options = [nil] : options = product.product_options 
product.product_sides.blank? ? sides = [nil] : sides = product.product_sides 
product.product_sizes.blank? ? sizes = [nil] : sizes = product.product_sizes 

valid_variants = [] 

sides.product(sizes, options).each do |side, size, option| 
    side.blank? ? side_id = nil : side_id = side.id 
    size.blank? ? size_id = nil : size_id = size.id 
    option.blank? ? option_id = nil : option_id = option.id 

    valid_variants << product.variants.where(product_size_id: size_id, product_side_id: side_id, product_option_id: option_id).first 
end 

在這種情況下product.variants不包含匹配側，大小和選擇IDS但valid_variants是空的變體。

這裏是product.variants的內容：

{"id"=>1, "product_side_id"=>nil, "product_size_id"=>1, "product_id"=>1, "created_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "updated_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "product_option_id"=>1} 
{"id"=>2, "product_side_id"=>nil, "product_size_id"=>1, "product_id"=>1, "created_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "updated_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "product_option_id"=>2} 
{"id"=>3, "product_side_id"=>nil, "product_size_id"=>2, "product_id"=>1, "created_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "updated_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "product_option_id"=>1} 
{"id"=>4, "product_side_id"=>nil, "product_size_id"=>2, "product_id"=>1, "created_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "updated_at"=>Mon, 27 Jan 2014 16:28:46 UTC +00:00, "product_option_id"=>2} 

下面是使用product.variants.where當valid_variants的內容（product_size_id：size_id，product_side_id：side_id，product_option_id：option_id）。首先

[nil, nil] 

下面是使用product.variants.where當valid_variants的內容（product_size_id：size_id，product_side_id：side_id，product_option_id：option_id）

[#<ActiveRecord::AssociationRelation []>] 

Answer 1

您將在每次迭代中重置valid_variants陣列。移動循環valid_variants = []外：

valid_variants = [] 
sides.product(sizes, options).each do |side, size, option| 
    side_id = side.blank? ? nil : side.id 
    size_id = size.blank? ? nil : size.id 
    option_id = option.blank? ? nil : option.id 

    valid_variants << product.variants.where(product_size_id: size_id, product_side_id: side_id, product_option_id: option_id).first 
end 

更新您的side_id，size_id和option_id初始化。