Defining models with fields in Django - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Django model with a character field named 'title'.

Django

from django.db import models

class Book(models.Model):
    title = models.[1](max_length=100)

Drag options to blanks, or click blank then click option'

ACharField

BIntegerField

CTextField

DDateField

Attempts:

3 left

💡 Hint

Common Mistakes

Using IntegerField for text data.

Forgetting to set max_length for CharField.

The CharField is used to define text fields with a maximum length in Django models.

2fill in blank

medium

Complete the code to add a date field named 'published_date' to the model.

Django

class Book(models.Model):
    published_date = models.[1]()

Drag options to blanks, or click blank then click option'

ACharField

BBooleanField

CIntegerField

DDateField

Attempts:

3 left

💡 Hint

Common Mistakes

Using CharField for dates.

Using IntegerField for dates.

The DateField is used to store date values in Django models.

3fill in blank

hard

Fix the error in the model field definition to store a number of pages as an integer.

Django

class Book(models.Model):
    pages = models.[1]()

Drag options to blanks, or click blank then click option'

ACharField

BIntegerField

CDateField

DTextField

Attempts:

3 left

💡 Hint

Common Mistakes

Using CharField with max_length for numbers.

Using max_length with IntegerField.

IntegerField is the correct field for storing numbers. max_length is not valid for IntegerField and should be removed.

4fill in blank

hard

Fill both blanks to define a Boolean field named 'is_bestseller' with default False.

Django

class Book(models.Model):
    is_bestseller = models.[1](default=[2])

Drag options to blanks, or click blank then click option'

ABooleanField

BFalse

CTrue

DCharField

Attempts:

3 left

💡 Hint

Common Mistakes

Using CharField for Boolean values.

Setting default to True instead of False.

BooleanField stores True/False values. Setting default=False means the field is False unless changed.

5fill in blank

hard

Fill all three blanks to create a model field 'rating' that stores decimal numbers with max 3 digits and 1 decimal place.

Django

class Book(models.Model):
    rating = models.[1](max_digits=[2], decimal_places=[3])

Drag options to blanks, or click blank then click option'

ADecimalField

B3

C1

DFloatField

Attempts:

3 left

💡 Hint

Common Mistakes

Using FloatField which can cause rounding errors.

Confusing max_digits and decimal_places.

DecimalField stores fixed-point decimal numbers. max_digits is total digits, decimal_places is digits after decimal.

Practice

1. What is the purpose of defining fields in a Django model?

easy

A. To create views for the web application

B. To specify the type of data each column will store in the database

C. To write HTML templates for the frontend

D. To handle user authentication automatically

Solution

1. Step 1: Understand Django model fields

   Fields in a Django model define what kind of data each column in the database will hold, such as text, numbers, or dates.

2. Step 2: Differentiate from other components

   Views handle logic, templates handle display, and authentication is separate; fields specifically define data structure.

3. Final Answer:

   To specify the type of data each column will store in the database -> Option B

4. Quick Check:

   Model fields = Data columns [OK]

Hint: Fields define data types in models, not views or templates [OK]

Common Mistakes:

• Confusing fields with views or templates
• Thinking fields handle user login
• Assuming fields control page layout

2. Which of the following is the correct way to define a character field named title with a maximum length of 100 in a Django model?

easy

A. title = models.IntegerField(max_length=100)

B. title = models.TextField(max_length=100)

C. title = models.CharField(length=100)

D. title = models.CharField(max_length=100)

Solution

1. Step 1: Identify correct field type and argument

   For text with length limit, CharField with max_length is correct.

2. Step 2: Check syntax correctness

   TextField does not use max_length, IntegerField is for numbers, and CharField requires max_length, not length.

3. Final Answer:

   title = models.CharField(max_length=100) -> Option D

4. Quick Check:

   CharField + max_length = correct syntax [OK]

Hint: Use CharField with max_length for short text fields [OK]

Common Mistakes:

• Using TextField with max_length
• Using IntegerField for text
• Writing length instead of max_length

3. Given the model definition below, what will be the default value of the is_active field for a new instance if not specified?

class User(models.Model):
    username = models.CharField(max_length=50)
    is_active = models.BooleanField(default=true)

medium

A. true

B. false

C. Raises an error

D. null

Solution

1. Step 1: Check Python syntax for booleans

   In Python and Django, booleans are True and False (capitalized). true is undefined.

2. Step 2: Model definition outcome

   Defining default=true raises NameError at model definition time, preventing instance creation.

3. Final Answer:

   Raises an error -> Option C

4. Quick Check:

   default=true -> NameError [OK]

Hint: Python/Django booleans: True/False (capitalized), not true/false [OK]

Common Mistakes:

• Assuming default is true despite syntax error
• Expecting null as default for BooleanField
• Using lowercase true/false in default

4. Identify the error in the following Django model field definition:

class Product(models.Model):
    price = models.DecimalField(max_digits=5, decimal_places=2, max_length=10)

medium

A. DecimalField does not accept max_length argument

B. max_digits should be less than decimal_places

C. DecimalField requires a default value

D. Field name 'price' is a reserved keyword

Solution

1. Step 1: Check DecimalField arguments

   DecimalField accepts max_digits and decimal_places, but not max_length.

2. Step 2: Validate argument usage

   Including max_length causes a syntax error because it's invalid for DecimalField.

3. Final Answer:

   DecimalField does not accept max_length argument -> Option A

4. Quick Check:

   DecimalField = max_digits + decimal_places only [OK]

Hint: DecimalField uses max_digits and decimal_places, not max_length [OK]

Common Mistakes:

• Adding max_length to DecimalField
• Mixing max_digits and decimal_places values incorrectly
• Assuming field names are reserved keywords

5. You want to create a Django model BlogPost with a title (max 200 chars), content (unlimited text), and a published date that can be empty. Which of the following is the best model definition?

hard

A. class BlogPost(models.Model):\n title = models.CharField(max_length=200)\n content = models.TextField()\n published_date = models.DateTimeField(blank=True, null=True)

B. class BlogPost(models.Model):\n title = models.TextField(max_length=200)\n content = models.CharField()\n published_date = models.DateTimeField()

C. class BlogPost(models.Model):\n title = models.CharField(max_length=200, blank=true)\n content = models.TextField()\n published_date = models.DateTimeField()

D. class BlogPost(models.Model):\n title = models.CharField(max_length=200)\n content = models.TextField()\n published_date = models.DateTimeField(default='')

Solution

1. Step 1: Match field types to requirements

   Title needs limited length, so CharField(max_length=200) is correct. Content is unlimited text, so TextField fits.

2. Step 2: Allow published_date to be empty

   To allow empty dates, use blank=True and null=True on DateTimeField.

3. Step 3: Check other options for errors

   class BlogPost(models.Model):\n title = models.TextField(max_length=200)\n content = models.CharField()\n published_date = models.DateTimeField() misuses TextField with max_length and swaps content types. class BlogPost(models.Model):\n title = models.CharField(max_length=200, blank=true)\n content = models.TextField()\n published_date = models.DateTimeField() does not allow empty published_date. class BlogPost(models.Model):\n title = models.CharField(max_length=200)\n content = models.TextField()\n published_date = models.DateTimeField(default='') uses invalid default for DateTimeField.

4. Final Answer:

   Correct field types with blank and null for published_date -> Option A

5. Quick Check:

   CharField + TextField + DateTimeField(blank=True, null=True) [OK]

Hint: Use blank=true and null=true to allow empty date fields [OK]

Common Mistakes:

• Using TextField with max_length
• Not allowing null for optional DateTimeField
• Setting invalid default values for DateTimeField