/save_data/ 处的 ValueError
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【中文标题】/save_data/ 处的 ValueError【英文标题】：ValueError at / save_data/ 【发布时间】：2021-10-28 04:32:47 【问题描述】：无法分配“'Electronic'”：“Product.category”必须是“Category”实例。
文件/models.py：
from django.db import models
# Create your models here.
class Category(models.Model):
name = models.CharField(max_length=150, db_index=True)
def __str__(self):
return self.name
class SubCategory(models.Model):
name = models.CharField(max_length=150, db_index=True)
category = models.ForeignKey(Category, related_name='souscatégories', on_delete=models.CASCADE)
def __str__(self):
return self.name
class Product(models.Model):
name = models.CharField(max_length=100, db_index=True)
category = models.ForeignKey(Category, on_delete=models.CASCADE)
subcategory = models.ForeignKey(SubCategory, on_delete=models.CASCADE)
def __str__(self):
return self.
还有业务逻辑代码...... 文件/views.py
# from django.urls import reverse_lazy
# from django.views.generic import ListView, CreateView
from django.shortcuts import render
from .models import Product, Category, SubCategory
# Create your views here.
def home(request):
if request.method == "POST":
name = request.POST['name']
subcategory = request.POST['subcategory']
category = request.POST['category']
ins = Product(name=name, subcategory=subcategory, category=category)
ins.save()
data = Product.objects.all()
return render(request, 'mysiteapp/index.html', 'data': data)
模板就在那里......
<!doctype html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>Hello, world!</title>
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"
integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
</head>
<body>
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<a class="navbar-brand" href="/">Product List </a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent"
aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item active">
<a class="nav-link" href="/">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item">
<a class="nav-link disabled" href="#">Disabled</a>
</li>
</ul>
<form class="form-inline my-2 my-lg-0">
<input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
<button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
</form>
</div>
</nav>
<!-- Table -->
<table class="table table-dark">
<thead>
<tr>
<th scope="col">#</th>
<th scope="col">Product</th>
<th scope="col">Subcategory</th>
<th scope="col">Category</th>
</tr>
</thead>
% for p in data%
<tbody>
<tr>
<th scope="row">p.id</th>
<td>p.name</td>
<td>p.subcategory</td>
<td>p.category</td>
</tr>
% endfor %
</tbody>
</table>
<!-- modal -->
<!-- Button trigger modal -->
<h2><a class="btn btn-success" data-toggle="modal" data-target="#exampleModal">
Add Product
</a></h2>
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel"
aria-hidden="true">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="exampleModalLabel">Add Product</h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<!-- form -->
<form method="POST">% csrf_token %
<div class="form-group row">
<label for="name" class="col-sm-2 col-form-label">Product</label>
<div class="col-sm-8">
<input name="name" type="text" id="name" class="form-control mx-sm-2">
</div>
</div>
<div class="form-group row">
<label for="subcategory" class="col-sm-2 col-form-label">SubCategory</label>
<div class="col-sm-8">
<select name="subcategory" class="custom-select mr-sm-2" id="subcategory">
<option>Choose....</option>
% for p in data %
<option>p.subcategory</option>
% endfor %
</select>
</div>
</div>
<div class="form-group row">
<label for="category" class="col-sm-2 col-form-label">Category</label>
<div class="col-sm-8">
<select name="category" class="custom-select mr-sm-2" id="category">
<option>Choose....</option>
% for p in data %
<option>p.category</option>
% endfor %
</select>
</div>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
<button type="submit" class="btn btn-primary">Save changes</button>
</div>
</form>
</div>
</div>
</div>
<!-- Optional javascript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin="anonymous"></script>
</body>
</html>
最后的错误是：
ValueError 在 / 无法分配“'Electronic'”：“Product.category”必须是“Category”实例。
请回答我...
【问题讨论】：
【参考方案1】：您不能直接从 POST 数据中传递类别。 要么它需要是 Category 类的实例
category_id = request.POST['category']
#Get category instance
category = Category.objects.get(pk=category_id)
ins = Product(name=name, subcategory=subcategory, category=category)
或者你可以使用类别pk值。
ins = Product(name=name, subcategory=subcategory, category_id=category_id)
【讨论】：
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