如何从 ruby on Rails 中的数据库函数获取单个结果？

Question

我正在尝试获取数据库函数的结果并将其存储在变量中。在此函数中，会传递一个收据 ID，并且根据是否启用收据，函数会返回

TRUE

或

FALSE

。请尝试以下方法：

 result = ActiveRecord::Base.connection.execute("SELECT receipt_enabled FROM schema.receipt_enabled(158800)") 
=> #<PG::Result:0x00556c7c374158 @connection=#<PG::Connection:0x00556c7d8ab3f0 @socket_io=nil, @notice_receiver=nil, @notice_processor=nil>> 

result = ActiveRecord::Base.connection.execute("SELECT receipt_enabled FROM schema.receipt_enabled(158800)").to_a
 => [{"receipt_enabled"=>"f"}]

result = ActiveRecord::Base.connection.select_all("SELECT receipt_enabled FROM schema.receipt_enabled(158800)").rows
=> [["f"]] 

我需要做类似的事情

if result == true
    @showreceipt = true
else
    @showreceipt = false
end

Answer 1

ActiveRecord::Result

有

cast_values

方法（它在底层使用

deserialize

）

query =
  <<~SQL
    SELECT receipt_enabled
    FROM schema.receipt_enabled(158800)
  SQL

ActiveRecord::Base.connection.exec_query(query).cast_values.flatten.first
# will return true or false