Question

考虑以下模型：

class Physician < ActiveRecord::Base
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ActiveRecord::Base
  belongs_to :physician
  belongs_to :patient
end

class Patient < ActiveRecord::Base
  has_many :appointments
  has_many :physicians, through: :appointments
end

目标：

创建患者（如果尚未存在）。
将患者添加到特定医生（如果尚未存在）

我想，我可以通过两种方式做到这一点：

方法1

physician = Physician.find(physician_id)
unless Patient.where(email: email).empty?
  record = physician.patients.create email: email
else
#Patient already exist, just add them to appointment
  record = Patient.where(email: email)
  physician.patients << record
end

方法2

physician = Physician.find(physician_id)
record = Patient.find_or_create_by(email: email)
# avoid overhead of SQL JOINS, use simple SELECT/CREATE
if Appointment.where(physician_id: physician_id).where(patient_id: record.id).empty?
   Appointment.create physician_id: physician.id, patient_id: record.id
end

现在，哪个是上述两个更好的方法？另外，在性能方面还有另一种比上述术语更好的方法吗？

Answer 1

选项3如何：

physician = Physician.find(physician_id)
unless physician.patients.where(email: email).exists?
  patient = Patient.find_or_create_by(email: email)
  physician.appointments.create(patient: patient)
end

如果患者已经与该医生预约，这将避免对find_or_create_by进行不必要的呼叫。

对于记录，调用model.association.create(...)将不会执行任何加入。它适用于表示关联的ActiveRelation对象，并且只会触发INSERT语句。但是，您建议的方法1还存在其他一些技术问题，而您的方法2也是不必要的冗长。

如果尚未在rails 4中预约，则将患者添加到Physician模型

1 个答案: