为什么 Django form.save() returns object(None)？

Question

from django.shortcuts import render
from django.forms import forms
from .models import Chart, ChartData
from .forms import ChartForm, ChartDataForm
import datetime

def home(request):
    chart_form = ChartForm(request.POST)
    chart_data_form = ChartDataForm(request.POST)
    context = {
        'chart_form': chart_form,
        'chart_data_form': chart_data_form,
    }
    if chart_form.is_valid():
        
        chart_obj = chart_form.save()
        chart = Chart.objects.get(pk=23)

        print(chart_obj)
        print(chart)

    
    return render(request, 'charts/home.html', context)

chart_form.save() returns "图表对象(None)

我最终必须将 chart_obj 传递给外键的另一个模型，但现在它在那里刹车并出现错误 - save() 被禁止以防止由于未保存的相关数据丢失对象.

在管理站点中，我看到对象已创建。

models.py低于

import datetime
from django.db import models
from django.forms import DateTimeField

# Create your models here.

class Chart(models.Model):
    id = models.IntegerField(primary_key=True)
    type = models.CharField(max_length=10)
    chartname = models.CharField(max_length=20, null=True)
    
class ChartData(models.Model):
    dataY = models.IntegerField()
    dataX = models.DateTimeField()
    chart = models.ForeignKey(Chart, on_delete=models.CASCADE)

forms.py以下

from django import forms
from .models import Chart, ChartData

class ChartForm(forms.ModelForm):
    class Meta:
        model = Chart
        fields = ['type','chartname']

class ChartDataForm(forms.ModelForm):
    class Meta:
        model = ChartData
        fields = ['dataY']

Answer 1

您应该在保存对象时使用 AutoField 来填充模型对象，因此：

class Chart(models.Model):
    id = models.<strong>AutoField(</strong>primary_key=True<strong>)</strong>
    type = models.CharField(max_length=10)
    chartname = models.CharField(max_length=20, null=True)

或者只是没有 id 字段：

class Chart(models.Model):
    type = models.CharField(max_length=10)
    chartname = models.CharField(max_length=20, null=True)

Answer 2

这里你不需要明确定义id，因为Django会为你做同样的事情。如果你想将主键重命名为其他东西，你可以使用下面的方法。

为什么 Django form.save() returns object(None)？

Why Django form.save() returns object(None)?

django

django-models

django-forms