A Django model is a Python class that represents a database table. Models make it easy to define and work with database tables using simple Python code. Instead of writing complex SQL queries, we use Django’s built-in ORM (Object Relational Mapper), which allows us to interact with the database in a more readable and organized way.
Key benefits of using Django models:
- Simplifies database operations like creating, updating, and deleting.
- Automatically generates SQL queries.
- Integrates with Django’s admin interface.
- Provides built-in validations and metadata handling.
Example
Python from django.db import models class GeeksModel(models.Model): title = models.CharField(max_length = 200) description = models.TextField()
This program defines a Django model called "GeeksModel" which has two fields:
- title: A character field with a 200-character limit.
- description: A text field for longer input.
This model creates a corresponding table in the database when migrations are applied. Django maps the fields defined in Django models into table fields of the database as shown below.
Creating a Django Model
1. To create Django Models, one needs to have a project and an app working in it. After you start an app you can create models in app_name/models.py. Before starting to use a model let's check how to start a project and create an app name geeksApp.
Refer to the following articles to check how to create a project and an app in Django.
2. In your app’s models.py file, define your model like this:
Python from django.db import models class GeeksModel(models.Model): title = models.CharField(max_length=200) description = models.TextField() last_modified = models.DateTimeField(auto_now_add=True) img = models.ImageField(upload_to="images/") def __str__(self): return self.title
This code defines a new Django model called "GeeksModel" which has four fields:
- title: a character field with a maximum length of 200.
- description: a text field.
- last_modified: a date and time field that automatically sets the date and time of creation.
- img: tores image uploads in the images/ directory.
- __str__ method is also defined to return the title of the instance of the model when the model is printed.
This code does not produce any output. It is defining a model class which can be used to create database tables and store data in Django.
Applying Migrations
Whenever we create a Model, Delete a Model, or update anything in any of models.py of our project. We need to run the following two commands
python manage.py makemigrations
python manage.py migrate
- makemigrations basically generates the SQL commands for preinstalled apps (which can be viewed in installed apps in settings.py) and your newly created app's model which you add in installed apps.
- migrate executes those SQL commands in the database file.
To know about Migrations in detail, visit: Basic App Model – Makemigrations and Migrate
Registering Models in Django Admin
To manage your model via the admin interface:
- Open admin.py in your app directory.
- Register your model:
Python from django.contrib import admin # Register your models here. from .models import GeeksModel admin.site.register(GeeksModel)
This code does not produce any output, it simply registers the GeeksModel with the admin site, so that it can be managed via the Django admin interface.
We can now use the admin panel to create, update, and delete model instances.
To check more on rendering models in django admin, visit - Render Model in Django Admin Interface
Basic CRUD Operations Using Django ORM
Django lets us interact with its database models, i.e. add, delete, modify and query objects, using a database-abstraction API called ORM(Object Relational Mapper). We can access the Django ORM by running the following command inside our project directory.
python manage.py shell
1. Adding Objects
To create an object of model Album and save it into the database, we need to write the following command:
Python a = GeeksModel( title="GeeksForGeeks", description="A description here", img="geeks/abc.png" ) a.save()
2. Retrieving Objects
To retrieve all the objects of a model, we write the following command:
GeeksModel.objects.all()
3. Modifying existing Objects
We can modify an existing object as follows:
a = GeeksModel.objects.get(id=3)
a.title = "Updated Title"
a.save()
4. Delete an Object
To delete a single object, we need to write the following commands:
a = GeeksModel.objects.get(id=2)
a.delete()
To check detailed post of Django's ORM (Object) visit Django ORM – Inserting, Updating & Deleting Data
Validation on Fields in a Model
Built-in Field Validations in Django models are the default validations that come predefined to all Django fields. Every field comes in with built-in validations from Django validators. For example, IntegerField comes with built-in validation that it can only store integer values and that too in a particular range.
Enter the following code into models.py file of geeks app.
Python from django.db import models from django.db.models import Model class GeeksModel(Model): geeks_field = models.IntegerField() def __str__(self): return self.geeks_field
After running makemigrations and migrate on Django and rendering above model, let us try to create an instance using string "GfG is Best".
You can see in the admin interface, one can not enter a string in an IntegerField. Similarly every field has its own validations. To know more about validations visit, Built-in Field Validations – Django Models
Read next: Basic App Model – Makemigrations and Migrate
Django Model data types and fields list
The most important part of a model and the only required part of a model is the list of database fields it defines. Fields are specified by class attributes. Here is a list of all Field types used in Django.
| Field Name | Description |
|---|
| AutoField | It An IntegerField that automatically increments. |
| BigAutoField | It is a 64-bit integer, much like an AutoField except that it is guaranteed to fit numbers from 1 to 9223372036854775807. |
| BigIntegerField | It is a 64-bit integer, much like an IntegerField except that it is guaranteed to fit numbers from -9223372036854775808 to 9223372036854775807. |
| BinaryField | A field to store raw binary data. |
| BooleanField | A true/false field.
The default form widget for this field is a CheckboxInput. |
| CharField | It is string filed for small to large-sized input |
| DateField | A date, represented in Python by a datetime.date instance |
| | It is used for date and time, represented in Python by a datetime.datetime instance. |
| DecimalField | It is a fixed-precision decimal number, represented in Python by a Decimal instance. |
| DurationField | A field for storing periods of time. |
| EmailField | It is a CharField that checks that the value is a valid email address. |
| FileField | It is a file-upload field. |
| FloatField | It is a floating-point number represented in Python by a float instance. |
| ImageField | It inherits all attributes and methods from FileField, but also validates that the uploaded object is a valid image. |
| IntegerField | It is an integer field. Values from -2147483648 to 2147483647 are safe in all databases supported by Django. |
| GenericIPAddressField | An IPv4 or IPv6 address, in string format (e.g. 192.0.2.30 or 2a02:42fe::4). |
| NullBooleanField | Like a BooleanField, but allows NULL as one of the options. |
| PositiveIntegerField | Like an IntegerField, but must be either positive or zero (0). |
| PositiveSmallIntegerField | Like a PositiveIntegerField, but only allows values under a certain (database-dependent) point. |
| SlugField | Slug is a newspaper term. A slug is a short label for something, containing only letters, numbers, underscores or hyphens. They’re generally used in URLs. |
| SmallIntegerField | It is like an IntegerField, but only allows values under a certain (database-dependent) point. |
| TextField | A large text field. The default form widget for this field is a Textarea. |
| TimeField | A time, represented in Python by a datetime.time instance. |
| URLField | A CharField for a URL, validated by URLValidator. |
| UUIDField | A field for storing universally unique identifiers. Uses Python’s UUID class. When used on PostgreSQL, this stores in a uuid datatype, otherwise in a char(32). |
Relationship Fields
Django also defines a set of fields that represent relations.
| Field Name | Description |
|---|
| ForeignKey | A many-to-one relationship. Requires two positional arguments: the class to which the model is related and the on_delete option. |
| ManyToManyField | A many-to-many relationship. Requires a positional argument: the class to which the model is related, which works exactly the same as it does for ForeignKey, including recursive and lazy relationships. |
| OneToOneField | A one-to-one relationship. Conceptually, this is similar to a ForeignKey with unique=True, but the “reverse” side of the relation will directly return a single object. |
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 CharField will enable it to store empty values for that table in relational database.
Here are the field options and attributes that an CharField can use.
| Field Options | Description |
|---|
| Null | If True, Django will store empty values as NULL in the database. Default is False. |
| Blank | If True, the field is allowed to be blank. Default is False. |
| db_column | The name of the database column to use for this field. If this isn’t given, Django will use the field’s name.
|
| Default | The 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_text | Extra “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_key | If True, this field is the primary key for the model. |
| editable | If 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_messages | The 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_text | Extra “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_name | A 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.
|
| validators | A list of validators to run for this field. See the validators documentation for more information.
|
| Unique | If True, this field must be unique throughout the table.
|
Defining models and fields
Create Model in Django
Similar Reads
Python Fundamentals
Python IntroductionPython was created 1991 with focus on code readability and express concepts in fewer lines of code.Simple and readable syntax makes it beginner-friendly.Runs seamlessly on Windows, macOS and Linux.Includes libraries for tasks like web development, data analysis and machine learning.Variable types ar
3 min read
Input and Output in PythonUnderstanding input and output operations is fundamental to Python programming. With the print() function, we can display output in various formats, while the input() function enables interaction with users by gathering input during program execution. Taking input in PythonPython's input() function
7 min read
Python VariablesIn Python, variables are used to store data that can be referenced and manipulated during program execution. A variable is essentially a name that is assigned to a value. Unlike many other programming languages, Python variables do not require explicit declaration of type. The type of the variable i
6 min read
Python OperatorsIn Python programming, Operators in general are used to perform operations on values and variables. These are standard symbols used for logical and arithmetic operations. In this article, we will look into different types of Python operators. OPERATORS: These are the special symbols. Eg- + , * , /,
6 min read
Python KeywordsKeywords in Python are reserved words that have special meanings and serve specific purposes in the language syntax. Python keywords cannot be used as the names of variables, functions, and classes or any other identifier. Getting List of all Python keywordsWe can also get all the keyword names usin
2 min read
Python Data TypesPython Data types are the classification or categorization of data items. It represents the kind of value that tells what operations can be performed on a particular data. Since everything is an object in Python programming, Python data types are classes and variables are instances (objects) of thes
9 min read
Conditional Statements in PythonConditional statements in Python are used to execute certain blocks of code based on specific conditions. These statements help control the flow of a program, making it behave differently in different situations.If Conditional Statement in PythonIf statement is the simplest form of a conditional sta
6 min read
Loops in Python - For, While and Nested LoopsLoops in Python are used to repeat actions efficiently. The main types are For loops (counting through items) and While loops (based on conditions). In this article, we will look at Python loops and understand their working with the help of examples. For Loop in PythonFor loops is used to iterate ov
9 min read
Python FunctionsPython Functions is a block of statements that does a specific task. The idea is to put some commonly or repeatedly done task together and make a function so that instead of writing the same code again and again for different inputs, we can do the function calls to reuse code contained in it over an
9 min read
Recursion in PythonRecursion is a programming technique where a function calls itself either directly or indirectly to solve a problem by breaking it into smaller, simpler subproblems.In Python, recursion is especially useful for problems that can be divided into identical smaller tasks, such as mathematical calculati
6 min read
Python Lambda FunctionsPython Lambda Functions are anonymous functions means that the function is without a name. As we already know the def keyword is used to define a normal function in Python. Similarly, the lambda keyword is used to define an anonymous function in Python. In the example, we defined a lambda function(u
6 min read
Python Data Structures
Python StringA string is a sequence of characters. Python treats anything inside quotes as a string. This includes letters, numbers, and symbols. Python has no character data type so single character is a string of length 1.Pythons = "GfG" print(s[1]) # access 2nd char s1 = s + s[0] # update print(s1) # printOut
6 min read
Python ListsIn Python, a list is a built-in dynamic sized array (automatically grows and shrinks). We can store all types of items (including another list) in a list. Can contain duplicate items.Mutable : We can modify, replace or delete the items. Ordered : Maintains the order of elements based on how they are
6 min read
Python TuplesA tuple in Python is an immutable ordered collection of elements. Tuples are similar to lists, but unlike lists, they cannot be changed after their creation (i.e., they are immutable). Tuples can hold elements of different data types. The main characteristics of tuples are being ordered , heterogene
6 min read
Dictionaries in PythonPython dictionary is a data structure that stores the value in key: value pairs. Values in a dictionary can be of any data type and can be duplicated, whereas keys can't be repeated and must be immutable. Example: Here, The data is stored in key:value pairs in dictionaries, which makes it easier to
7 min read
Python SetsPython set is an unordered collection of multiple items having different datatypes. In Python, sets are mutable, unindexed and do not contain duplicates. The order of elements in a set is not preserved and can change.Creating a Set in PythonIn Python, the most basic and efficient method for creating
10 min read
Python ArraysLists in Python are the most flexible and commonly used data structure for sequential storage. They are similar to arrays in other languages but with several key differences:Dynamic Typing: Python lists can hold elements of different types in the same list. We can have an integer, a string and even
9 min read
List Comprehension in PythonList comprehension is a concise and powerful way to create new lists by applying an expression to each item in an existing iterable (like a list, tuple or range). It helps you write clean, readable and efficient code compared to traditional loops.Syntax[expression for item in iterable if condition]P
4 min read
Advanced Python
Python OOP ConceptsObject Oriented Programming is a fundamental concept in Python, empowering developers to build modular, maintainable, and scalable applications. OOPs is a way of organizing code that uses objects and classes to represent real-world entities and their behavior. In OOPs, object has attributes thing th
11 min read
Python Exception HandlingPython Exception Handling handles errors that occur during the execution of a program. Exception handling allows to respond to the error, instead of crashing the running program. It enables you to catch and manage errors, making your code more robust and user-friendly. Let's look at an example:Handl
6 min read
File Handling in PythonFile handling refers to the process of performing operations on a file, such as creating, opening, reading, writing and closing it through a programming interface. It involves managing the data flow between the program and the file system on the storage device, ensuring that data is handled safely a
4 min read
Python Database TutorialPython being a high-level language provides support for various databases. We can connect and run queries for a particular database using Python and without writing raw queries in the terminal or shell of that particular database, we just need to have that database installed in our system.A database
4 min read
Python MongoDB TutorialMongoDB is a popular NoSQL database designed to store and manage data flexibly and at scale. Unlike traditional relational databases that use tables and rows, MongoDB stores data as JSON-like documents using a format called BSON (Binary JSON). This document-oriented model makes it easy to handle com
2 min read
Python MySQLMySQL is a widely used open-source relational database for managing structured data. Integrating it with Python enables efficient data storage, retrieval and manipulation within applications. To work with MySQL in Python, we use MySQL Connector, a driver that enables seamless integration between the
9 min read
Python PackagesPython packages are a way to organize and structure code by grouping related modules into directories. A package is essentially a folder that contains an __init__.py file and one or more Python files (modules). This organization helps manage and reuse code effectively, especially in larger projects.
12 min read
Python ModulesPython Module is a file that contains built-in functions, classes,its and variables. There are many Python modules, each with its specific work.In this article, we will cover all about Python modules, such as How to create our own simple module, Import Python modules, From statements in Python, we c
7 min read
Python DSA LibrariesData Structures and Algorithms (DSA) serve as the backbone for efficient problem-solving and software development. Python, known for its simplicity and versatility, offers a plethora of libraries and packages that facilitate the implementation of various DSA concepts. In this article, we'll delve in
15 min read
List of Python GUI Library and PackagesGraphical User Interfaces (GUIs) play a pivotal role in enhancing user interaction and experience. Python, known for its simplicity and versatility, has evolved into a prominent choice for building GUI applications. With the advent of Python 3, developers have been equipped with lots of tools and li
11 min read
Data Science with Python
NumPy Tutorial - Python LibraryNumPy is a core Python library for numerical computing, built for handling large arrays and matrices efficiently.ndarray object – Stores homogeneous data in n-dimensional arrays for fast processing.Vectorized operations – Perform element-wise calculations without explicit loops.Broadcasting – Apply
3 min read
Pandas TutorialPandas (stands for Python Data Analysis) is an open-source software library designed for data manipulation and analysis. Revolves around two primary Data structures: Series (1D) and DataFrame (2D)Built on top of NumPy, efficiently manages large datasets, offering tools for data cleaning, transformat
6 min read
Matplotlib TutorialMatplotlib is an open-source visualization library for the Python programming language, widely used for creating static, animated and interactive plots. It provides an object-oriented API for embedding plots into applications using general-purpose GUI toolkits like Tkinter, Qt, GTK and wxPython. It
5 min read
Python Seaborn TutorialSeaborn is a library mostly used for statistical plotting in Python. It is built on top of Matplotlib and provides beautiful default styles and color palettes to make statistical plots more attractive.In this tutorial, we will learn about Python Seaborn from basics to advance using a huge dataset of
15+ min read
StatsModel Library- TutorialStatsmodels is a useful Python library for doing statistics and hypothesis testing. It provides tools for fitting various statistical models, performing tests and analyzing data. It is especially used for tasks in data science ,economics and other fields where understanding data is important. It is
4 min read
Learning Model Building in Scikit-learnBuilding machine learning models from scratch can be complex and time-consuming. Scikit-learn which is an open-source Python library which helps in making machine learning more accessible. It provides a straightforward, consistent interface for a variety of tasks like classification, regression, clu
8 min read
TensorFlow TutorialTensorFlow is an open-source machine-learning framework developed by Google. It is written in Python, making it accessible and easy to understand. It is designed to build and train machine learning (ML) and deep learning models. It is highly scalable for both research and production.It supports CPUs
2 min read
PyTorch TutorialPyTorch is an open-source deep learning framework designed to simplify the process of building neural networks and machine learning models. With its dynamic computation graph, PyTorch allows developers to modify the network’s behavior in real-time, making it an excellent choice for both beginners an
7 min read
Web Development with Python
Flask TutorialFlask is a lightweight and powerful web framework for Python. It’s often called a "micro-framework" because it provides the essentials for web development without unnecessary complexity. Unlike Django, which comes with built-in features like authentication and an admin panel, Flask keeps things mini
8 min read
Django Tutorial | Learn Django FrameworkDjango is a Python framework that simplifies web development by handling complex tasks for you. It follows the "Don't Repeat Yourself" (DRY) principle, promoting reusable components and making development faster. With built-in features like user authentication, database connections, and CRUD operati
10 min read
Django ORM - Inserting, Updating & Deleting DataDjango's Object-Relational Mapping (ORM) is one of the key features that simplifies interaction with the database. It allows developers to define their database schema in Python classes and manage data without writing raw SQL queries. The Django ORM bridges the gap between Python objects and databas
4 min read
Templating With Jinja2 in FlaskFlask is a lightweight WSGI framework that is built on Python programming. WSGI simply means Web Server Gateway Interface. Flask is widely used as a backend to develop a fully-fledged Website. And to make a sure website, templating is very important. Flask is supported by inbuilt template support na
6 min read
Django TemplatesTemplates are the third and most important part of Django's MVT Structure. A Django template is basically an HTML file that can also include CSS and JavaScript. The Django framework uses these templates to dynamically generate web pages that users interact with. Since Django primarily handles the ba
7 min read
Python | Build a REST API using FlaskPrerequisite: Introduction to Rest API REST stands for REpresentational State Transfer and is an architectural style used in modern web development. It defines a set or rules/constraints for a web application to send and receive data. In this article, we will build a REST API in Python using the Fla
3 min read
How to Create a basic API using Django Rest Framework ?Django REST Framework (DRF) is a powerful extension of Django that helps you build APIs quickly and easily. It simplifies exposing your Django models as RESTfulAPIs, which can be consumed by frontend apps, mobile clients or other services.Before creating an API, there are three main steps to underst
4 min read
Python Practice
Python QuizThese Python quiz questions are designed to help you become more familiar with Python and test your knowledge across various topics. From Python basics to advanced concepts, these topic-specific quizzes offer a comprehensive way to practice and assess your understanding of Python concepts. These Pyt
3 min read
Python Coding PracticeThis collection of Python coding practice problems is designed to help you improve your overall programming skills in Python.The links below lead to different topic pages, each containing coding problems, and this page also includes links to quizzes. You need to log in first to write your code. Your
1 min read
Python Interview Questions and AnswersPython is the most used language in top companies such as Intel, IBM, NASA, Pixar, Netflix, Facebook, JP Morgan Chase, Spotify and many more because of its simplicity and powerful libraries. To crack their Online Assessment and Interview Rounds as a Python developer, we need to master important Pyth
15+ min read