如何在rails中使用like子句查询？

我想在搜索关键字时获得 json 格式的数据，所以我使用 LIKE 子句并像这样查询

"select * from employees where fname like ? or mname like ? or lname like ? or username like ? or id like ?", str, str, str, str, str

但我想使用 Rails 对其进行编码。我的控制器中有这段代码

def showemployees
  str = params[:str]
  render json: @employee = Employee.where(Employee.employees[:fname].matches("%#{str}%")) or
    (Employee.employees[:mname].matches("%#{str}%")) or
    (Employee.employees[:lname].matches("%#{str}%")) or
    (Employee.employees[:id].matches("%#{str}%"))
end

这段代码在我的 config/routes.rb 中

get 'employees/showemployees'
root :to => 'employees#new'
resources :employees
post 'employees/update_info'

当我输入这个时http://localhost:3000/employees/showemployees?str=samplename http://localhost:3000/employees/showemployees?str=samplename，应该会出现 json 格式的记录，但我收到此错误消息

undefined method `employees' for #<Class:0x8e38900>
app/controllers/employees_controller.rb:6:in `showemployees'

其中第 6 行有此代码

render json: @employee = Employee.where(Employee.employees[:fname].matches("%#{str}%")) or

您可以链接 where 查询，但是这个AND每个where查询结果

Employee.where('fname LIKE ?', "%#{str}%").where('lname LIKE ?', "%#{str}%").where('mname LIKE ?', "%#{str}%").where('username LIKE ?', "%#{str}%").where('id LIKE ?', "%#{str}%")

或使用OR clause

Employee.where('fname LIKE ? OR lname LIKE ? OR mname', "%#{str}%", "%#{str}%", "%#{str}%")