python - 如何过滤数据库表行并更新 Django 中的特定列？

Question

我有一个数据库表，我想按 id 过滤它并用我写的 if 条件更新特定对象(列)。但它得到一个错误:attributeError: 'int' 对象没有属性 'save'

models.py

class Forcast(models.Model):                                                        
    current_complete = models.FloatField(null=True)                                                                    
    optimestic = models.BooleanField(null=True)
    probable = models.BooleanField(null=True)
    pessimistic = models.BooleanField(null=True)
    optimestic_percentage = models.FloatField(null=True)
    probable_percentage = models.FloatField(null=True)
    pessimistic_percentage = models.FloatField(null=True)
    weight = models.FloatField(null=True)




views.py

 def update(request, id):
    item = Forcast.objects.get(id=id)
    if request.method == 'POST':
        form = CharacterNoteForm(request.POST, instance=item)
        if form.is_valid():
            current_complete = Forcast.objects.values('current_complete').get(id=id)
            print(current_complete['current_complete'])
            weight = Forcast.objects.values('weight').get(id=id)
            print(weight)
            optimestic = form.cleaned_data['optimestic']
            probable = form.cleaned_data['probable']
            pessimistic = form.cleaned_data['pessimistic']
            if current_complete['current_complete'] == 65.0 and optimestic:
                optimestic_percentagex = current_complete['current_complete'] * weight['weight']
                if probable or pessimistic:
                    probable_percentagey = current_complete['current_complete'] * weight['weight']
                    pessimistic_percentagez = current_complete['current_complete'] * weight['weight']
                obj = Forcast.objects.filter(id=id).update(optimestic_percentage=optimestic_percentagex)

我除了可以使用我创建的 if 条件更新 optimestic_percentage。有关更多信息，我正在使用 postgresql

Answer 1

你的代码看起来不错，但是 django 框架是用 python 开发的，这意味着你可以使用 Pythonic 的方式找到问题的解决方案，这样你就可以使用 psycopg2 库连接你的数据库并更新你的数据

import psycopg2

try:
    conncetion = psycopg2.connect(user='db_user',
                                  password='***',
                                  host='192.168.0.0',
                                  port='5432',
                                  database='****')
    cursor = conncetion.cursor()

    query_update = ''' UPDATE forecast_Table SET optimestic_percentage = ''' +   optimestic_percentagex + ''' WHERE id= ''' + id + ''' '''
    cursor.execute(query_update)
    conncetion.commit()
    count = cursor.rowcount
    print(count, "Record inserted successfully into forecast table")
except (Exception, psycopg2.Error) as error:
    print("Failed to insert record into forecast table", error)