Screencast: Fortgeschrittene Abfragen in Rails 3

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Resourcen:

• Episode 202: Active Record Queries in Rails 3
• Arel
• MetaWhere
• Full episode source code

Quellcode:

[ruby] # rails console Product.cheap.to_sql (Category.joins(:products) & Product.cheap).to_sql Category.with_cheap_products.to_sql p = Product.discontinued.build p.discontinued t = Product.arel_table t[:price].eq(2.99) t[:name].matches(“%catan”).to_sql Product.where(t[:price].eq(2.99).or(t[:name].matches(“%catan”)))

# models/product.rb scope :discontinued, where(:discontinued => true)

def self.cheaper_than(price) where(“products.price < ?”, price) end

scope :cheap, cheaper_than(5)

# models/category.rb scope :with_cheap_products, joins(:products) & Product.cheap [/ruby]