I'm new to django (and python) and I have a question.
I have this model:
class Material(models.Model):
name = models.CharField(max_length=256, blank=True)
description = models.TextField(null=True, blank=True)
def __str__(self):
return self.name
class Meta:
abstract = True
and
class Experiments(models.Model):
title = models.CharField(max_length=200)
experiment = models.TextField(null=True, blank=True)
def __str__(self):
return self.title
I want to query it so I have only have the Materials used in the Experiments model. I was reading about Q objects but I'm not sure how to use it. I appreciate any help!
Related
I am trying to create an educational website using django, so I have two models class and course which have a one-to-many foreignkey relationship between them i.e. one course can have several class but one class can only have one course. But this creates a problem for me. That is, in my course_detail_view I have assigned the model course. So I cannot render classes in my html file. Can anyone help me solve this ?
My models.py:
class Course(models.Model):
title = models.CharField(max_length=100)
image = models.ImageField(upload_to='class/instructor_pics', null=True)
instructor = models.CharField(max_length=100)
instructor_image = models.ImageField(upload_to='class/instructor_pics', null=True)
students = models.ManyToManyField(User, related_name='courses_joined', blank=True)
slug = models.SlugField(max_length=200, unique=True)
description = models.TextField(max_length=300, null=True)
created = models.DateTimeField(auto_now_add=True)
class Meta:
ordering = ['-created']
def __str__(self):
return self.title
class Class(models.Model):
title = models.CharField(max_length=100)
video = models.FileField(upload_to='class/class_videos',null=True,
validators=[FileExtensionValidator(allowed_extensions=['MOV','avi','mp4','webm','mkv'])])
course = models.ForeignKey(Course, on_delete=models.CASCADE, null=True, related_name='classes')
def __str__(self):
return self.title
My views.py:
class CourseDetailView(LoginRequiredMixin, DetailView):
model = Course
template_name = 'class/course.html'
Thanks in advance!
I am trying to create an educational website using django so I have a class model and a course model. I have tried to use the Many-to-one foreignkey relationship but that doesn't work, I can create classes using foreignkey but that class is not being assigned to that course only. It appears in other courses as well. So how can I make this work? What should I change?
My models.py:
class Class(models.Model):
title = models.CharField(max_length=100)
video = models.FileField(upload_to='class/class_videos',null=True,
validators=[FileExtensionValidator(allowed_extensions=['MOV','avi','mp4','webm','mkv'])])
def __str__(self):
return self.title
class Course(models.Model):
title = models.CharField(max_length=100)
image = models.ImageField(upload_to='class/instructor_pics', null=True)
instructor = models.CharField(max_length=100)
instructor_image = models.ImageField(upload_to='class/instructor_pics', null=True)
students = models.ManyToManyField(User, related_name='courses_joined', blank=True)
classes = models.ForeignKey(Class, on_delete=models.CASCADE, null=True)
slug = models.SlugField(max_length=200, unique=True)
description = models.TextField(max_length=300, null=True)
created = models.DateTimeField(auto_now_add=True)
class Meta:
ordering = ['-created']
def __str__(self):
return self.title
You are using the foreign key in the wrong model. If each class can only have one course, but a single course, can have multiple classes, you should place the ForeignKey in the class model instead of the course model. Your code would be like this:
class Course(models.Model):
title = models.CharField(max_length=100)
image = models.ImageField(upload_to='class/instructor_pics', null=True)
instructor = models.CharField(max_length=100)
instructor_image = models.ImageField(upload_to='class/instructor_pics', null=True)
students = models.ManyToManyField(User, related_name='courses_joined', blank=True)
slug = models.SlugField(max_length=200, unique=True)
description = models.TextField(max_length=300, null=True)
created = models.DateTimeField(auto_now_add=True)
class Meta:
ordering = ['-created']
def __str__(self):
return self.title
class Class(models.Model):
title = models.CharField(max_length=100)
video = models.FileField(upload_to='class/class_videos',null=True,
validators=[FileExtensionValidator(allowed_extensions=['MOV','avi','mp4','webm','mkv'])])
course = models.ForeignKey(Course, on_delete=models.CASCADE, null=True, related_name='classes')
def __str__(self):
return self.title
And when you want to list the classes of a single course, you can use this code (you should use the related_name field in the source model like the way I have used in the class model):
course = Course.objects.filter(some_filter=some_value).first()
course.classes.first() # This will return the first class of the course
I have below models and form.
Brand > Section > Category > Article.
I can pull the existing data out of the database however I have hit a wall. I am trying to create a new article or update an existing article but I'm not sure how I can update the brand, then the Section. The Category I can update and it is connected directly to the Article model. I have been thinking about this for a few days now and tried different models but ultimately i can't think of the best way to connect the models and have them update in the model.
class Brand(models.Model):
def brand_image(instance, filename):
return 'uploads/brand/{0}/{1}'.format(instance.title, filename)
title = models.CharField(max_length=50, unique=True, blank=True, null=True)
image = models.ImageField(upload_to=brand_image, null=True, blank=True)
slug = AutoSlugField(populate_from='title', unique_with='title', blank=True, null=True)
my_order = models.PositiveIntegerField(default=0, blank=False, null=False)
class Meta:
ordering = ['my_order']
def __str__(self):
return self.title or ''
def get_absolute_url(self):
return reverse('brand-list', kwargs={'brand_slug': self.slug})
class Section(models.Model):
title = models.CharField(max_length=50,unique=True, blank=True,null=True)
slug = AutoSlugField(populate_from='title', unique_with='title',blank=True,null=True)
brand = models.ForeignKey(Brand, on_delete=models.CASCADE, related_name='section', blank=False, null=False)
my_order = models.PositiveIntegerField(default=0, blank=False, null=False)
class Meta:
ordering = ['my_order']
def __str__(self):
return self.title or ''
def get_absolute_url(self):
return reverse('section-list', kwargs={'section_slug': self.slug})
class Category(models.Model):
title = models.CharField(max_length=50, blank=True,null=True)
slug = AutoSlugField(populate_from='title', unique_with='title',blank=True,null=True)
my_order = models.PositiveIntegerField(default=0, blank=False, null=False)
section = models.ForeignKey(Section, on_delete=models.CASCADE,related_name='category', blank=False ,null=False)
class Meta:
ordering = ['my_order']
def __str__(self):
return self.title or ''
def get_absolute_url(self):
return reverse('category-list', kwargs={'category_slug': self.slug})
class Article(models.Model):
title = models.CharField(max_length=100, unique=True, db_index=True)
description = models.CharField(max_length=100, blank=True, null=False)
category = models.ForeignKey(Category, on_delete=PROTECT, related_name='article', null=False, default=1)
slug = AutoSlugField(populate_from='title', unique_with='created__month')
content = HTMLField(null=True,blank=True)
internal = models.BooleanField(default=False)
status = models.CharField(max_length=30, choices=STATUS_CHOICES, default='Draft')
author = models.ForeignKey(User, related_name='author' ,on_delete=PROTECT,null=True)
updated_by = models.ForeignKey(User, related_name='updated_by',on_delete=PROTECT,null=True)
created = models.DateTimeField(auto_now_add=True)
updated = models.DateTimeField(auto_now=True)
video = models.FileField(blank=True, null=True, upload_to='articles/videos')
favourites = models.ManyToManyField(User, related_name='art_favourite', default=None, blank=True)
tags = TaggableManager(related_name='tags', help_text='Comma or space separated list', blank=True)
pinned = models.BooleanField(default=False)
def __str__(self) -> str:
return self.title
def get_absolute_url(self):
return reverse('articles-detail', kwargs={'article_slug': self.slug})
class ArticleForm(forms.ModelForm):
title = forms.CharField(label='Article Title', max_length=100,)
description = forms.CharField(label='Description', max_length=100,required=False)
content = forms.CharField(label='Article Content',widget=CKEditorUploadingWidget(attrs={'cols': 80, 'rows': 30}))
video = forms.FileField(help_text="Valid file Extension - .mp4", required=False, validators=[validate_file_extension])
category = GroupedModelChoiceField(queryset=Category.objects.exclude(section=None).order_by('section'),choices_groupby='section')
internal = forms.BooleanField(required=False, help_text='Is this for internal use only?', label='Internal Article')
class Meta:
model = Article
exclude = ['slug','author','created','updated','updated_by','favourites','votes','views','section']
widgets = {"tags": TagWidget(attrs={"data-role": "tagsinput"})}
Any help or guidance would be greatly appreciated.
Your Article model has a foreign key link to Section for some reason. However your stated heirarchy and models use the following one-to-many relations, which creates a direct link up the chain.
Brand < Section < Category < Article.
This means that by choosing the Category you could also choose Brand and Section. If your Article had a foreign key link to Category instead, then all the information above about groups above Article could be obtained via the article, eg, article.category__section__brand. Changing the category would, by default, update section and brand. You could do this in a single dropdown that contained Category.objects.all - perhaps with the dropdown option text also containing brand and section info for clarity and sorting purposes.
I am new to Python and Django.
I am trying to build myself very simple blog application.
So I have this 2 models :
class Tag(models.Model):
name = models.CharField(max_length=250)
slug = models.SlugField(unique=True)
def __unicode__(self):
return self.name
class Blogpost(models.Model):
title = models.CharField(max_length=300)
content = tinymce_models.HTMLField()
date_created = models.DateTimeField(auto_now_add=True)
date_updated = models.DateTimeField(auto_now=True)
tags = models.ManyToManyField(Tag)
def __unicode__(self):
return self.title
As you can see Blogpost can contain many Tags,
my question is how can I query Blogpost.objects.all() to get Blogposts list by specific Tag?
Thank you.
I think related manager is your answer
t = Tag.objects.get(name="Some tag")
t.blogpost_set.all()
I have the following sets of models (abbreviated for clarity):
First set:
class Web(Link):
ideas = models.ManyToManyField(Idea, blank=True, null=True)
precedents = models.ManyToManyField(Precedent, blank=True, null=True)
categories = GenericRelation(CategoryItem)
#permalink
def get_absolute_url(self):
return ('resources-link-detail', [str(self.slug)])
which is a child of:
class Link(models.Model):
title = models.CharField(max_length=250)
description = models.TextField(blank=True)
website = models.URLField(unique=True)
slug = models.SlugField(unique_for_date='pub_date')
...
#permalink
def get_absolute_url(self):
return ('link-detail', [str(self.slug)])
Second set
class ResourceOrganization(Organization):
ideas = models.ManyToManyField(Idea, blank=True, null=True)
precedents = models.ManyToManyField(Precedent, blank=True, null=True)
categories = GenericRelation(CategoryItem)
#permalink
def get_absolute_url(self):
return ('resources-org-detail', [str(self.slug)])
which is a child of:
class Organization(Contact):
name = models.CharField(max_length=100)
org_type = models.PositiveSmallIntegerField(choices=ORG_CHOICES)
...
#permalink
def get_absolute_url(self):
return ('org-detail', [str(self.slug)])
which is a child of:
class Contact(models.Model):
description = models.TextField(blank=True, null=True)
address_line1 = models.CharField(max_length=250, blank=True)
address_line2 = models.CharField(max_length=250, blank=True)
slug = models.SlugField(unique=True)
...
class Meta:
abstract = True
The "ResourceOrganization" model is properly overiding the get_absolute_url method and is adding the "categories" generic relation.
The "Web" model is not.
I'm at a loss to figure out why. Would appreciate any insight.
P.S. I'm realizing that there may have been better ways to implement this functionality, but I'm stuck with it for the moment until I can refactor and would like to get it working.
Thanks.
If anyone else is running into this problem, take a look at any custom managers you have defined on the parent model. They will not inherit to the child model in the way you might think.
http://docs.djangoproject.com/en/dev/topics/db/managers/#custom-managers-and-model-inheritance