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DateTimeField – Django Models

  • Difficulty Level : Easy
  • Last Updated : 12 Feb, 2020

DateTimeField is a date and time field which stores date, represented in Python by a datetime.datetime instance. As the name suggests, this field is used to store an object of datetime created in python. The default form widget for this field is a TextInput. The admin uses two separate TextInput widgets with JavaScript shortcuts.

Syntax

field_name = models.DateTimeField(**options)
DateTimeField has the following extra optional arguments –
  • DateTimeField.auto_now

    Automatically set the field to now every time the object is saved. Useful for “last-modified” timestamps. Note that the current date is always used; it’s not just a default value that you can override.
    The field is only automatically updated when calling Model.save(). The field isn’t updated when making updates to other fields in other ways such as QuerySet.update(), though you can specify a custom value for the field in an update like that.

  • DateTimeField.auto_now_add

    Automatically set the field to now when the object is first created. Useful for creation of timestamps. Note that the current date is always used; it’s not just a default value that you can override. So even if you set a value for this field when creating the object, it will be ignored. If you want to be able to modify this field, set the following instead of auto_now_add=True:

    • For DateTimeField: default=datetime.now – from datetime.now()
    • For DateTimeField: default=timezone.now – from django.utils.timezone.now()

Note: The options auto_now_add, auto_now, and default are mutually exclusive. Any combination of these options will result in an error.

Django Model DateTimeField Explanation

Illustration of DateTimeField using an Example. Consider a project named geeksforgeeks having an app named geeks.



Refer to the following articles to check how to create a project and an app in Django.

Enter the following code into models.py file of geeks app.




from django.db import models
from django.db.models import Model
# Create your models here.
  
class GeeksModel(Model):
    geeks_field = models.DateTimeField()

Add the geeks app to INSTALLED_APPS




# Application definition
  
INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'geeks',
]

Now when we run makemigrations command from the terminal,

Python manage.py makemigrations

A new folder named migrations would be created in geeks directory with a file named 0001_initial.py




# Generated by Django 2.2.5 on 2019-09-25 06:00
  
from django.db import migrations, models
  
class Migration(migrations.Migration):
  
    initial = True
  
    dependencies = [
    ]
  
    operations = [
        migrations.CreateModel(
            name ='GeeksModel',
            fields =[
                ('id'
                  models.AutoField(
                  auto_created = True,
                  primary_key = True,
                  serialize = False
                  verbose_name ='ID'
                )),
                ('geeks_field', models.DateTimeField()),
            ],
        ),
    ]

Now run,

Python manage.py migrate

Thus, an geeks_field DateTimeField is created when you run migrations on the project. It is a field to store datetime.datetime python object.

How to use DateTimeField ?

DateTimeField is used for storing python datetime.datetime instance in the database. One can store any type of date and time using the same in the database. Let’s try storing a date in model created above.




# importing the model
# from geeks app
from geeks.models import GeeksModel
  
# importing datetime module
import datetime
  
# creating an instance of 
# datetime.date
d = datetime(2015, 10, 09, 23, 55, 59, 342380)
  
# creating an instance of 
# GeeksModel
geek_object = GeeksModel.objects.create(geeks_field = d)
geek_object.save()

Now let’s check it in admin server. We have created an instance of GeeksModel.
DateTimeField django models

Field Options

Field Options are the arguments given to each field for applying some constraint or imparting a particular characteristic to a particular Field. For example, adding an argument null = True to DateTimeField will enable it to store empty values for that table in relational database.
Here are the field options and attributes that an DateTimeField can use.

Field OptionsDescription
NullIf True, Django will store empty values as NULL in the database. Default is False.
BlankIf True, the field is allowed to be blank. Default is False.
db_columnThe name of the database column to use for this field. If this isn’t given, Django will use the field’s name.
DefaultThe default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.
help_textExtra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t used on a form.
primary_keyIf True, this field is the primary key for the model.
editableIf False, the field will not be displayed in the admin or any other ModelForm. They are also skipped during model validation. Default is True.
error_messagesThe error_messages argument lets you override the default messages that the field will raise. Pass in a dictionary with keys matching the error messages you want to override.
help_textExtra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t used on a form.
verbose_nameA human-readable name for the field. If the verbose name isn’t given, Django will automatically create it using the field’s attribute name, converting underscores to spaces.
validatorsA list of validators to run for this field. See the validators documentation for more information.
UniqueIf True, this field must be unique throughout the table.

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