good day to everyone, i had the name error in this code, someone can explain me why, please???
category = models.ManyToManyField(Category) NameError: name 'Category' is not defined
from django.db import models
from datetime import datetime
# Create your models here.
class Store(models.Model):
business_name = models.CharField(max_length=100, null=False, verbose_name='Nombre')
nit = models.PositiveIntegerField(null=False,default=0,verbose_name='NIT')
category = models.ManyToManyField(Category)
def __str__(self):
return self.business_name
class Meta:
db_table = 'Store'
verbose_name = 'Tienda'
verbose_name_plural = 'Tiendas'
ordering = ['id']
class Category(models.Model):
name = models.CharField(max_length=150, verbose_name='Name')
def __str__(self):
return self.name
class Meta:
verbose_name = 'Categoria'
verbose_name_plural = 'Categorias'
ordering = ['id']
thanks for your comments
When python is reading the file, it gets to the category = models.ManyToManyField(Category) but doesnt know what Category is yet,
Move the Category class BEFORE Store, and all will work.
Related
I'm using python 3.7
django 2.2
django rest framework 3.9.4
After running:
python manage.py migrate
An error comes out:
ValueError: invalid literal for int() with base 10: 'category'
This is my model:
class Category(models.Model):
name = models.CharField(max_length=40, default='', verbose_name="类别名", help_text="类别名") # 分类名
class Meta:
verbose_name = "分类"
verbose_name_plural = verbose_name
def __str__(self):
return self.name
class Article(models.Model):
...code...
category = models.ForeignKey(Category, on_delete=models.CASCADE, related_name="cate", blank=True, verbose_name='分类',
default='')
...code...
class Meta:
ordering = ['-add_time']
verbose_name = "新闻"
verbose_name_plural = verbose_name
def __str__(self):
return self.title # 在后台中以文章标题显示
This is my serizalizers.py
class CategorySerializer(serializers.ModelSerializer):
class Meta:
model = Category
fields = "__all__"
class ArticleSerializer(serializers.ModelSerializer):
# 外键相关对象
tag = TagSerializer(many=True)
category = CategorySerializer()
class Meta:
model = Article
fields = "__all__"
Any friend can help?
I think the error is that you're defining the default value for the category foreign key as '', when it should be None. Also you should set null = True instead of blank = True.
class Article(models.Model):
...code...
category = models.ForeignKey(
Category,
on_delete=models.CASCADE,
related_name="cate",
null=True, # change here
verbose_name='分类',
default=None # and here
)
...code...
Delete migrations and run migrate again.
I'm trying to add a data using "Array Model Field"(djongo) as shown Djongo Documentation(Array Model Field) or
from djongo import models
class Blog(models.Model):
name = models.CharField(max_length=100)
tagline = models.TextField()
class Meta:
abstract = True
class MetaData(models.Model):
pub_date = models.DateField()
mod_date = models.DateField()
n_pingbacks = models.IntegerField()
rating = models.IntegerField()
class Meta:
abstract = True
class Author(models.Model):
name = models.CharField(max_length=200)
email = models.EmailField()
class Meta:
abstract = True
def __str__(self):
return self.name
class Entry(models.Model):
blog = models.EmbeddedModelField(
model_container=Blog,
)
meta_data = models.EmbeddedModelField(
model_container=MetaData,
)
headline = models.CharField(max_length=255)
body_text = models.TextField()
authors = models.ArrayModelField(
model_container=Author,
)
n_comments = models.IntegerField()
def __str__(self):
return self.headline
Into admin.py I added for registration of model in admin panel
from django.contrib import admin
from .models import Entry
admin.site.register(Entry)
And when I try to add a data via http://localhost:8000/admin/ I have a MigrationError...
Where is my mistake? And what am I not understanding?
You should use models.ObjectIdField() on all models to avoid calling django migrations.
Example:
class Author(models.Model):
_id = models.ObjectIdField()
name = models.CharField(max_length=200)
email = models.EmailField()
class Meta:
abstract = True
def __str__(self):
return self.name
See more in Djongo Docs
I'm a stupid. Sry. I didn't 'makemigration' after update a model.
And so here's what I did to make it work:
1. After update a model I did 'python manage.py makemigrations' and that power on.
I want to define a relationship between Book and Member through Borrow in models.py
ER
But I don't know how to define the Borrow relationship.
In the Borrow table it must be determined which books have been borrowed by who and which books have been returned on which date. Should I use another table for this date field?
models.py
from django.contrib.auth.models import AbstractUser
from django.db import models
from django.utils.translation import gettext as _
class CategoryType(models.Model):
category_name = models.CharField(max_length=200)
def __str__(self):
return self.category_name
class Book(models.Model):
name = models.CharField(verbose_name="عنوان", max_length=128)
number_of_copy = models.IntegerField(default=0)
writer = models.CharField(max_length=64)
B_category = models.ForeignKey(CategoryType, on_delete=models.CASCADE)
class Meta:
ordering = ["B_category"]
def __str__(self):
return self.name
class Borrow(models.Model):
borrowed_from_date = models.DateField(_("borrow Date"), default=0)
borrowed_to_date = models.DateField(_("return Date"), default=3)
actual_return_date = models.DateField()
borrowed_by = models.ForeignKey(member, on_delete=models.CASCADE)
books = models.ManyToManyField(Book)
def __str__(self):
return self.id
class Member(AbstractUser):
pass
I think in the Member class I should have a field containing borrow_id, but how?
It seems to me that you need to use a ManyToMany relationship with a through model (this way you can store extra information for every row of the Borrow model)
...
class Borrow(models.Model):
borrowed_from_date = models.DateField(_("borrow Date"), default=0)
borrowed_to_date = models.DateField(_("return Date"), default=3)
actual_return_date = models.DateField()
borrowed_by = models.ForeignKey(Member, on_delete=models.CASCADE)
book = models.ForeignKey(Book)
def __str__(self):
return self.id
...
class Member(AbstractUser):
borrowed_books = models.ManyToManyField(Book, through='Borrow')
Maybe this link (https://docs.djangoproject.com/es/2.1/ref/models/fields/#django.db.models.ManyToManyField.through) could clarify it more.
I have a little problem. In my models.py file I have two classes:
class Categories and class Websites.
In Categories by the admin panel I added many records of categories. How to show in html file for example : how many webstites were added in the category 'Company' or in the another categories?
Here is my models.py
from django.db import models
from django.utils import timezone
class Kategorie(models.Model):
glowna = models.CharField(max_length=150, verbose_name='Kategoria')
class Meta:
verbose_name='Kategoria'
verbose_name_plural='Kategorie'
def __str__(self):
return self.glowna
class Witryna(models.Model):
nazwa = models.CharField(default="", max_length=150, verbose_name = 'Nazwa strony')
adres_www = models.CharField(max_length=70, verbose_name='Adres www')
slug = models.SlugField(max_length=250, verbose_name='Przyjazny adres url')
email = models.CharField(max_length=100, verbose_name='Adres e-mail')
text = models.TextField(max_length=3000, verbose_name='Opis strony')
kategoria = models.ForeignKey(Kategorie, verbose_name='Kategoria')
data_publikacji = models.DateTimeField(blank=True, null=True, verbose_name='Data publikacji')
class Meta:
verbose_name='Strona www'
verbose_name_plural = 'Strony www'
def publikacja(self):
self.data_publikacji=timezone.now()
self.save()
def __str__(self):
return self.nazwa
I have just started learning Django Rest Framework and trying to make a simple API using Django rest Framework.
This is my models.py
from __future__ import unicode_literals
from django.db import models
class Student(models.Model):
created = models.DateTimeField(auto_now_add=True)
name = models.CharField(max_length=150, blank=False)
student_id = models.CharField(max_length=20, primary_key=True)
father_name = models.CharField(max_length=150)
mother_name = models.CharField(max_length=150)
class Meta:
ordering = ('student_id',)
class Subject(models.Model):
created = models.DateTimeField(auto_now_add=True)
subject_id = models.CharField(max_length=20, primary_key=True)
name = models.CharField(max_length=150)
class Meta:
ordering = ('subject_id',)
class Result(models.Model):
created = models.DateTimeField(auto_now_add=True)
grade = models.DecimalField(max_digits=5, decimal_places=3, blank=False)
student_id = models.ForeignKey(Student, on_delete=models.CASCADE)
subject_id = models.ForeignKey(Subject, on_delete=models.CASCADE)
class Meta:
ordering = ('created',)
And this is my serializers.py
from rest_framework import serializers
from models import *
class StudentSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Student
fields = ('student_id', 'name', 'father_name', 'mother_name')
class SubjectSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Subject
fields = ('subject_id', 'name')
class ResultSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Result
fields = ('grade', 'student_id', 'subject_id')
In my "Result" model, I have two foreign keys; student_id and subject_id. This is how it looks like:
My questions is, how can I show the "name" field in the drop down menu in stead of showing "Student Object" and "Subject Object"?
I have tried with
STUDENT_CHOICES = [(each.student_id, each.name) for each in Student.objects.all()]
SUBJECT_CHOICES = [(each.subject_id, each.name) for each in Subject.objects.all()]
in the model's "choices=" field but it didn't work out.
Thanks in advance.
I think you're looking for this part of the DRF documentation.
Basically, your Django model's own representation is used. So for example, in your Student model you can add __str__ method:
# this is for Python 3, use __unicode__ on Python 2
def __str__(self):
return self.name
Meta options documentation for Django is here, look for model methods.