帶有任何created_at的Railswhere方法

我有這樣的方法：

def transfers(material, capacity, category, created_at)
  transfers_range = Transfer.first.created_at..Transfer.last.created_at if created_at.nil?
  Transfer.where(
    sender_dispensary_id: id,
    status: %i[dispatched released returned],
    capacity: capacity,
    material: material,
    created_at: created_at.nil? ? transfers_range : Time.given_month_range(created_at)
  ).or(
    Transfer.where(
      receiver_dispensary_id: id,
      status: %i[dispatched released returned],
      capacity: capacity,
      material_id: material,
      created_at: created_at.nil? ? transfers_range : Time.given_month_range(created_at)
    )
  )
end

它正在作業，但是有沒有辦法避免查詢transfer_range？我的意思是......如果created_at == nil，那么這個函式應該跳過created_at列，就像它沒有包含在查詢中一樣

uj5u.com熱心網友回復：

什么時候基本上created_at涵蓋了所有轉移，因此條件是沒有意義的，在這種情況下我會簡單地查詢。niltransfers_rangecreated_at

def transfers(material, capacity, category, created_at)
  transfers = Transfer
    .where(status: %i[dispatched released returned], capacity: capacity, material_id: material)
    .where('sender_dispensary_id = :id OR receiver_dispensary_id = :id', id: id)

  transfer = transfer.where(created_at: Time.given_month_range(created_at)) if created_at

  transfer
end

uj5u.com熱心網友回復：

是的，transfers_range可以通過將查詢分成多行并created_at分別添加存在條件來避免查詢。您還可以將兩個 OR 查詢組合成一個查詢，如下所示：

def transfers(material, capacity, category, created_at)
  transfer_data = Transfer.where('sender_dispensary_id = ? OR receiver_dispensary_id = ?', id).where(status: %i[dispatched released returned], capacity: capacity, material_id: material)
  transfer_data = transfer_data.where(created_at: Time.given_month_range(created_at)) if created_at.present?
  transfer_data
end

uj5u.com熱心網友回復：

您可以整合 created_at 查詢邏輯，以便將其放在一個位置，而無需重復。

  created_at = if created_at.nil?
    Transfer.first.created_at..Transfer.last.created_at
  else
    Time.given_month_range(created_at)
  end

您也不需要重復整個 where 條件兩次。你想要相當于...

where status in ('dispatched', 'released', 'returned')
  and capacity = ?
  and material = ?
  and created_at = ?
  and (
    sender_dispensary_id = ?
    or
    receiver_dispensary_id = ?
  )

你這樣做：

  Transfer
    .where(
      status: %i[dispatched released returned],
      capacity: capacity,
      material: material,
      created_at: created_at
    )
    .where(
      Transfer
        .where(receiver_dispensary_id: id)
          .or(Transfer.where(sender_dispensary_id: id))
    )
  )

通過將邏輯放入scopes中，您可以使其更加簡潔，并隱藏細節。

class Transfer < Application
  scope :by_dispensary_id ->(id) {
    where(receiver_dispensary_id: id)
      .or(where(sender_dispensary_id: id))
  }

  scope :by_created_month ->(time) {
    if time.nil?
      where(created_at: first.created_at..last.created_at)
    else
      where(created_at: Time.given_month_range(time))
    end
  }
end

現在查詢要簡單得多。

  Transfer
    .by_dispensary_id(id)
    .by_created_month(created_at)
    .where(
      status: %i[dispatched released returned],
      capacity: capacity,
      material: material
    )
  )

標籤：轨道上的红宝石 红宝石 PostgreSQL ruby-on-rails-6.1

上一篇：Rubyonrails-API添加狀態路由

下一篇：為什么我收到內部服務器錯誤500？