Develop Reference

How can I make DRF Serializer create() function only create an entry that does not exist yet?

I have two tables, which are connected with each other through a cross table. (Recipes <--> Ingredients)
My Serializer works ok, I can send POST-Requests and it saves everything. The problem ist, that every time a new Recipe comes in with let just say the Ingredient "Milk" then my Serializer creates a new entry in my database named Milk, although I have an already existing entry "Milk" in my database.
How do I tell my Serializer to use the Id of an already existing entry instead of creating a new one every time for the cross table.
Here is how I thought I could fix it, but it clearly doesn't:
class RecipeIngredientSerializer(serializers.ModelSerializer):
ingredient = IngerdientSerializer()
class Meta:
model = recipe_ingredients
fields = ['amount', 'unit', 'ingredient']
def create(self, validated_data):
ingredient_validated_data = validated_data.pop('ingredient')
ingredient_serializer = self.fields['ingredient']
ingredientDict = dict(ingredient_validated_data)
// This is where I try to check if there is already an ingredient with the name from the form
ingredientObj = ingredient.objects.all().filter(ingredient_name=ingredientDict['ingredient_name']).
if not ingredientObj:
ingredient_instance = ingredient.objects.create(**ingredientDict)
validated_data['ingredient'] = ingredient_instance
else:
ingredient_instance = ingredient_serializer.create(ingredientDict)
validated_data['ingredient'] = ingredient_instance
recipe_ingredients_instance = recipe_ingredients.objects.create(**validated_data)
return recipe_ingredients_instance
This code also seems to work, at least I find an existing ingredient, but after the last create() it seems to ignore what ever I push into the validated_data['ingredient'] object.
EDIT
my models are:
class recipe_ingredients(models.Model):
recipe = models.ForeignKey(recipe, models.CASCADE)
ingredient = models.ForeignKey(ingredient, models.CASCADE)
amount = models.IntegerField(default=0)
unit = models.CharField(max_length=50)
def __str__(self):
return self.ingredient.ingredient_name + ' of Recipe: ' + self.recipe.recipe_name
class recipe(models.Model):
recipe_name = models.CharField(max_length=200)
assembly_time = models.IntegerField(default=0)
number_of_servings = models.IntegerField(default=0)
tags = models.ManyToManyField(tag, blank=True)
def __str__(self):
return self.recipe_name
class ingredient(models.Model):
ingredient_name = models.CharField(max_length=200)
ingredient_calories = models.IntegerField('Calories per 100 Units', default=-1)
default_unit = models.CharField(max_length=50)
def __str__(self):
return self.ingredient_name

I got the answer, finally. My mistake is this line in my Serializer:
ingredientObj = ingredient.objects.all().filter(ingredient_name=ingredientDict['ingredient_name']).
if not ingredientObj:
ingredient_instance = ingredient.objects.create(**ingredientDict)
validated_data['ingredient'] = ingredient_instance
I changed it now so that it looks something like this:
ingredientObj = ingredient.objects.all().filter(ingredient_name=ingredientDict['ingredient_name']).
if len(ingredientObj):
ingredient_instance = ingredientObj.first()
validated_data['ingredient'] = ingredient_instance
The ingredient.object.create(**ingredientDict) does actually create a new object (who would have known ;) ). This is probably still an ugly solution and I am open to more criticism but this does work for now.

Insert multiple keywords in one field

My question is how i can insert multiple keywords in one django field and show them in a template like stackoverflow tags.
Models:
class Jobs(models.Model):
title = models.CharField(max_length=100)
slug = models.SlugField(blank=True, default='')
company = models.ForeignKey(Company, on_delete=models.CASCADE)
tags = ?????

Create another class and use many-to-many relationship between jobs class (tags) and new class:
class Tags(models.Model):
tag_name=models.CharField()
In jobs class
tags=models.ManyToManyField(Tags)
For show in template you can use for loop, etc.

Make it a Comma separated value.
class Jobs(models.Model):
tags = models.TextField()
def tag_list(self):
return self.tags.split(",")
def add_tag(self, tag_str):
current_tags = self.tag_list()
current_tags.append(tag_str)
current_tags = set(current_tags)
new_tag_string = ",".join(current_tags)
self.tags = new_tag_string
# you could save the model now or let caller save it outside of this method. I suggest letting caller save the model.
def remove_tag(self, tag_str):
current_tags = self.tag_list()
current_tags.remove(tag_str)
new_tag_string = ",".join(current_tags)
self.tags = new_tag_string
# you could save the model now or let caller save it outside of this method. I suggest letting caller save the model.

Pull object from database in views.py

I would like to create a function in views.py to retrieve an information from this class:
class Vin(models.Model):
def __unicode__ (self):
return self.nom
name = models.CharField( max_length = 30)
year = models.CharField (max_length = 4)
appellation = models.ForeignKey(Appellation)
photo = models.CharField (max_length = 70)
quantity = models.IntegerField ()
released = models.IntegerField()
and retrieve it by its attribute "name".
So for instance, if i have a Wine ("chardonnay", 1990, ...) only retrieve chardonnay.
Thanks !

Your view function will be called after the user enters a URL that is in your urls.py. The url entered may provide you with the additional information you need to query the database and get information on the Vin object you need.
If you want a view to just return every Vin in your database. Something like this might be helpful for you:
def get_vins(request, *args, **kwargs):
vins = Vin.objects.all().values_list('name', flat=True)
return render(request, 'somepage.html', {"vins": vins})
Your question is really vauge and you should read the django documentation. This is a very basic question that all starters should learn.

How to snip Django TextField?

I want to create a simple blog using Django, this is my code :
class Blog(models.Model):
title = models.CharField(max_length = 50)
content = models.TextField(max_length = 10000)
publication_date = models.DateField(blank = True, null = True)
author = models.CharField(max_length = 50)
image = models.ImageField(upload_to='image',verbose_name = 'My photos',blank = True)
def __str__(self):
return self.title
When I display the content field, I don't know how to add images (in the body of content field) , strong text, ...
Is there anyone can show me how to do this?, sorry if it's a silly question,
I've searched for hours but I didn't find out the answer

This is to be done using Rich text editors. See the list of available django packages here. CKEditor and TinyMCE are promising to easily handle images.

Auto Incrementing natural keys with django / postgres

Let me preface this in saying that I'm a UI dev who's trying to branch out into more backend coding, so excuse me if my verbiage is off at all. This is could be a duplicate, but i'm not sure what on god's good green earth i'm even supposed to call what i want to do.
Basically, I have categories, and images. I need to label each image with an acronym of the category it belongs to, and increment a sku after.
For Example, the following images would be automatically labeled like...
ABC-1
ABC-2
DEF-1
DEF-2
DEF-3
ABC-3*
*note: I want it to increment the ID based on the category, not the total # of images
How would I achieve this in idiomatic Django?
Models:
class Group(models.Model):
title = models.CharField(max_length=200)
abbv = models.CharField(max_length=200)
urlified = models.CharField(max_length=200)
description = models.TextField(blank=True)
hidden = models.BooleanField()
def __unicode__(self):
return self.title
class Photo(models.Model):
group = models.ForeignKey(Group)
title = models.CharField(max_length=200)
description = models.TextField(blank=True)
pub_date = models.DateTimeField(auto_now_add = True, blank=True)
image = models.ImageField(max_length=100)
class Meta:
ordering = ('pub_date',)

If you want true composed primary keys, you might want to use django-compositepks, but that is not ideal. You might be better off breaking DRY and recording the number (see the category_auto_key field and default).
Transactions will solve it this way:
from django.db import transaction
class Group(models.model):
# your fields
img_count = models.IntegerField()
#transaction.atomic
def next_sku(self):
self.img_count += 1
self.save()
return self.img_count
class Photo(models.Model):
# your fields
category_auto_key = models.IntegerField(editable=False)
def category_image(self):
return self.group.abbv+"-"+str(self.category_auto_key)
def save(self, *args, **kwargs):
if not self.category_auto_key:
self.category_auto_key = self.group.next_sku()
super(Photo, self).save(*args, **kwargs)
When you need this in your templates, just enclose it in double brackets:
{{ photo.category_image }}

I'm curious if you just want to generate and store the acronym and sku in a text field, or if you are trying to create relationships between your image categories?
If the later, I would look for a different approach.
If the former, i would use a customized set or save method (hook?) for your image model. It will need do a small one time lookup to count the number of acronym already existing, but I wouldn't worry about the performance too much.
Wasn't sure how to do this exactly in Django off the top of my head, but it looks like the accepted answer works similarly. Anyways, here is my attempt at setting a Model Field during save. Be warned this in untested.
After looking into it more I think that Beltiras' solution is better
class Photo(models.Model):
# simple column definitions
group = models.ForeignKey(Group)
title = models.CharField(max_length=200)
description = models.TextField(blank=True)
pub_date = models.DateTimeField(auto_now_add = True, blank=True)
image = models.ImageField(max_length=100)
# new column for storing abbv sku
category_label = models.CharField(max_length=200)
# save override
def save(self, *args, **kwargs):
# hopefully only set category_label on first save, not sure this
# works, open to other ideas
if (self.pk is None):
count = Photo.objects.filter(group=self.group).count()
label = self.group.abbv + '-' + count
setattr(self, 'category_label', label)
# call the super class' save method
super(Photo, self).save(*args, ** kwargs)
The part I am least sure about is:
count = Photo.objects.filter(group=self.group).count()
The idea is to query the photos table for photos in the same group and count them. This may need to be replaced with a direct SQL call or done some other way. Let me know what you find.