带有 Pyramid 的 Sqlalchemy 批量插入答案

【问题标题】：Sqlalchemy bulk insert with Pyramid带有 Pyramid 的 Sqlalchemy 批量插入
【发布时间】：2013-03-17 04:18:30
【问题描述】：

我有一个需要使用循环插入多次的对象。每次循环迭代我都会更改一些字段值。我的代码是：

@view_config(route_name="be.bautocredits.rates.add",
             request_method="POST",
             permission="admin",
             renderer="json")
def _add_rates(self):
    _ = self.request.translate
    controls = self.request.POST.items()
    schema = AutocreditRateSchema()
    try:
        schema.deserialize(controls)
        rate = AutocreditRate()
        rate.autocredit = Autocredit.by_rid(self.request.POST.get('_autocredits_rid'))
        rate.carshow = Carshow.by_rid(self.request.POST.get('_carshows_rid'))
        rate.currency = Currency.by_rid(self.request.POST.get('_currencies_rid'))
        rate.min_cost_currency = Currency.by_rid(self.request.POST.get('min_cost_currencies_rid'))
        rate.max_cost_currency = Currency.by_rid(self.request.POST.get('max_cost_currencies_rid'))
        rate.min_currency = Currency.by_rid(self.request.POST.get('min_currencies_rid'))
        rate.max_currency = Currency.by_rid(self.request.POST.get('max_currencies_rid'))
        rate.manufacturer = Manufacturer.by_rid(self.request.POST.get('_manufacturers_rid'))
        rate.autocredit.updated = datetime.datetime.now()

        _cars_rids = list(set(self.request.POST.getall('_cars_rid')))
        if _cars_rids:
            for _cars_rid in _cars_rids:
                rate.car = Car.by_rid(_cars_rid)
                DBSession.add(rate)
        else:
            DBSession.add(rate)

    except colander.Invalid, e:
        return dict(errors=dict(e.asdict().items()+dict(status_bar=_(u'Check errors')).items()))
    return dict()

此代码仅插入单行。由于某些原因，我无法直接在“尝试块”开始时设置循环。我做错了什么？

【问题讨论】：

标签： python sqlalchemy pyramid

【解决方案1】：

DBSession.add 向会话添加一个对象（顾名思义）——当时没有发出 SQL 查询，.add 只是让会话知道该对象。

在提交会话之前，您可以继续修改对象的属性 - 无论您将对象添加到会话中多少次，只会将一行添加到数据库中。

您也许可以通过一些巧妙的会话刷新来做您想做的事情，但是，说真的，为什么不为每一行创建一个单独的对象呢？这就是 ORM 通常的工作方式。

def _add_rates(self):
    _ = self.request.translate
    controls = self.request.POST.items()
    schema = AutocreditRateSchema()
    try:
        schema.deserialize(controls)
        _cars_rids = list(set(self.request.POST.getall('_cars_rid')))
        autocredit = Autocredit.by_rid(self.request.POST.get('_autocredits_rid'))
        carshow = Carshow.by_rid(self.request.POST.get('_carshows_rid'))
        currency = Currency.by_rid(self.request.POST.get('_currencies_rid'))
        min_cost_currency = Currency.by_rid(self.request.POST.get('min_cost_currencies_rid'))
        max_cost_currency = Currency.by_rid(self.request.POST.get('max_cost_currencies_rid'))
        min_currency = Currency.by_rid(self.request.POST.get('min_currencies_rid'))
        max_currency = Currency.by_rid(self.request.POST.get('max_currencies_rid'))
        manufacturer = Manufacturer.by_rid(self.request.POST.get('_manufacturers_rid'))
        if _cars_rids:
            for _cars_rid in _cars_rids:
                rate = AutocreditRate(autocredit=autocredit, carshow=carshow, ...)
                rate.car = Car.by_rid(_cars_rid)
                rate.autocredit.updated = datetime.datetime.now()
                DBSession.add(rate)
        else:
            rate = AutocreditRate(autocredit=autocredit, carshow=carshow, ...)
            rate.autocredit.updated = datetime.datetime.now()
            DBSession.add(rate)

【讨论】：