One to many mapping with a ChainMap Dictionary Question: I would like do a one to many mapping with the following list and mapping dictonary: l1 = [‘a’, ‘b’, ‘c’] l2 = [‘a’, ‘c’, ‘d’] l3 = [‘d’, ‘e’, ‘f’] mapping_dict = ChainMap( dict.fromkeys(l1, ‘A’), dict.fromkeys(l2, ‘B’), dict.fromkeys(l3, ‘C’)) This is my dataframe: df = …
Create one object and bulk-create many related objects Question: Am new to Django (and Python) and have a problem initializing my model. For every school year created in the database, I want the corresponding days (not exactly 365/366, but > 300) to be created with a default value of 0 (a one-to-many relationship). I learned …
How to parse the many values of one-to-many relationship into HTML template in Django? Question: I have a one-to-many relationship in Django as such: class Listing(models.Model): title = models.CharField(max_length=60) class Images(models.Model): listings = models.ForeignKey(Listing, on_delete=models.CASCADE) image_urls = models.URLField(max_length = 200) I have the following view defined: from .models import Listing, Images def index(request): All_Listings = …
__init__() got an unexpected keyword argument 'author' for one to many Question: So, im trying to reference a users post ? and i keep getting this error error >>> from app import db, models >>> u = models.User.query.get(2) >>> p = models.Post(title=’barn owl’, body=’thompson’, author=u) Traceback (most recent call last): File "<stdin>", line 1, in …
AttributeError: 'int' object has no attribute '_sa_instance_state' Question: I’m working on forum template using Flask. When I attempt creating a new thread in the browser using forms, SQLAlchemy throws an AttributeError. The problem showed up when I tried implementing a one-to-many relationship with Forum-to-Thread and a one-to-many relationship with Thread-to-User. models.py class User(db.Model): id = …
