Django model blank=True, but sql always NOT NULL

Question

I am building a Django website from a tutorial. The model is called Post and looks like this:

class Post(models.Model):
   author = models.ForeignKey('auth.User', verbose_name='Author')
   title = models.CharField(max_length=200, verbose_name='Titel')
   text = HTMLField()
   created_date = models.DateTimeField(default=timezone.now, verbose_name='Erstellungsdatum')
   published = models.BooleanField(blank=True, verbose_name='Veröffentlichung')
   tags = models.ManyToManyField(Tag, blank=True)

   class Meta:
       verbose_name = 'Artikel'
       verbose_name_plural = 'Artikels'
       ordering = ['-created_date']

   def publish(self):
       self.published = True
       self.save()

   def __str__(self):
       return self.title

as you can see, i made some fields blank=True .

The migration/sql Django is now performing looks like this:

ALTER TABLE "blog_post" RENAME TO "blog_post__old";
CREATE TABLE "blog_post" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, 
"published" bool NOT NULL, "title" varchar(200) NOT NULL, "text" text NOT 
NULL, "created_date" datetime NOT NULL, "author_id" integer NOT NULL 
REFERENCES "auth_user" ("id"));
INSERT INTO "blog_post" ("id", "title", "text", "created_date", "author_id", 
"published") SELECT "id", "title", "text", "created_date", "author_id", 
"published" FROM "blog_post__old";
DROP TABLE "blog_post__old";
CREATE INDEX "blog_post_author_id_dd7a8485" ON "blog_post" ("author_id");
COMMIT;

It just ignores the blank-values and makes every field NOT NULL. i saw this also in this question

The problem is, that if i implement the form in the template this field is "required" input, so the form cannot be submitted if the checkbox is unchecked.

Thanks in advance!

forms.py

from django import forms
from tinymce.widgets import TinyMCE

from .models import Post

class PostForm(forms.ModelForm):

    text = forms.CharField(widget=TinyMCE(attrs={'cols': 80, 'rows': 30, 'class': 'materialize-textarea'}))
    published = forms.BooleanField(widget=forms.CheckboxInput())

    class Meta:
        model = Post
        fields = ('title', 'published', 'text', 'tags')

template

{% extends 'blog/base.html' %}

{% block content_block %}
    <div class="row">
        <h1>Edit Post</h1>
    </div>

<div class="row">
    <form class="col s12" action="" method="POST">
    {% csrf_token %}
    {{ form.as_p }}
    <button type="submit" class="waves-effect waves-light btn"><i class="material-icons left">save</i>Speichern</button>
    </form>
</div>

{% endblock %}

Answer 1

published = models.BooleanField(blank=True, verbose_name='Veröffentlichung')

source refer the docs django model references

Note that this is different than null. null is purely database-related, whereas blank is validation-related. If a field has blank=True, form validation will allow entry of an empty value. If a field has blank=False, the field will be required.

In your forms

published = forms.BooleanField(required=False,widget=forms.CheckboxInput())

Source Requred filed

Hope its working

Answer 2

The BooleanField can store True or False , so having NOT NULL isn't a problem.

If you really want to allow null for a field, then you need null=True . This is a separate option from blank=True which you already have.

You shouldn't need to override the boolean field in your model form, since it is already a checkbox. However, if you do override it, then you need to set required=False if you want the field to be optional.

published = forms.BooleanField(widget=forms.CheckboxInput(), required=False)