使用ActiveRecord :: Base＃valid只验证一个属性？

Question

我正在寻找一种使用ActiveRecord::Base#valid? 只有一个属性。 考虑以下示例，该示例受RailsGuides的启发：

class Product < ActiveRecord::Base
  belongs_to :company

  validates :legacy_code, format: { with: /\A[a-zA-Z]+\z/ }
  validates :name, uniqueness: { scope: :company }
end

调用Product#valid? 由于name验证，将触发SQL查询：

Product.new(legacy_code: "helloworld", company: c).valid?
  Product Exists (0.3ms)  SELECT  1 AS one FROM "products"  WHERE ("products"."name" IS NULL AND "products"."company_id" = 1) LIMIT 1
=> true

现在，我只想验证legacy_code属性：

Product.new(legacy_code: "helloworld").valid?
  Product Exists (0.2ms)  SELECT  1 AS one FROM "products"  WHERE ("products"."name" IS NULL AND "products"."company_id" IS NULL) LIMIT 1
=> true

看到问题了吗？ 我很想使用类似于Product#valid?(:legacy_code)并且避免使用试图验证我不关心的属性的查询。

到目前为止，我的解决方案是使用Product#valid_legacy_code? 我可以独立调用的方法，也可以在模型的验证声明中调用此方法。

Answer 1

我最终为此写了一个宝石： https : //github.com/KevinBongart/valid_attribute

# Test only one attribute:
product.valid_attribute?(:company)      # => true
product.valid_attribute?(:name)         # => true
product.valid_attribute?(:legacy_code)  # => false

# Test several attributes at once, like a boss:
product.valid_attribute?(:company, :name)               # => true
product.valid_attribute?(:company, :name, :legacy_code) # => false

# Wow, you can even filter down to a specific validator:
product.valid_attribute?(name: :format)                     # => true
product.valid_attribute?(name: [:format, :uniqueness])      # => true
product.valid_attribute?(name: :format, company: :presence) # => true