Field types (CharField, IntegerField, DateField) in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the default max length of a CharField in Django?

Consider the following Django model field:

name = models.CharField()

What will happen when you run migrations?

A It defaults max_length to 255 automatically

B It sets max_length to 100 by default

C It raises a TypeError because max_length is required

D It allows unlimited length strings

💡 Hint

Think about what Django requires for CharField length.

CharField requires max_length to be specified. Omitting it causes a TypeError during migration generation.

❓ state_output

intermediate

What value is stored in the database for this IntegerField?

Given this model field:

age = models.IntegerField(default=18)

What will be the value of age if you create a new instance without specifying age?

A None

B 18

C 0

D Raises an error for missing value

💡 Hint

Check the default parameter behavior.

The default value 18 is used when no value is provided during instance creation.

📝 Syntax

advanced

Which option correctly defines a DateField that allows empty values?

You want a DateField that can be empty in the database and in forms. Which is correct?

A birth_date = models.DateField()

B birth_date = models.DateField(blank=True)

C birth_date = models.DateField(null=True)

D birth_date = models.DateField(blank=True, null=True)

💡 Hint

Remember the difference between blank and null in Django fields.

null=True allows database to store NULL; blank=True allows form to accept empty input. Both are needed for optional DateField.

🔧 Debug

advanced

Why does this model raise an error on migration?

Model code:

class Person(models.Model):
    name = models.CharField(max_length=50)
    age = models.IntegerField(blank=True)

What is the cause of the error?

A IntegerField cannot have blank=True without null=True

B CharField max_length must be greater than 50

C Missing default value for age field

D Models must have a primary key defined explicitly

💡 Hint

Check the meaning of blank and null for IntegerField.

IntegerField with blank=True but without null=True causes validation error because blank affects forms but null affects database storage.

🧠 Conceptual

expert

How does Django handle DateField input from forms when blank=True and null=True are set?

If a DateField has blank=True and null=True, what happens when a user submits an empty date in a form?

A The field stores NULL in the database and passes validation

B The field stores an empty string in the database

C The form raises a validation error for empty input

D The field stores the current date automatically

💡 Hint

Think about how blank and null affect form and database behavior.

blank=True allows empty form input; null=True allows storing NULL in database. So empty input is valid and stored as NULL.

Practice

1. Which Django field type is best for storing a person's full name with a limit on characters?
class Person(models.Model):
name = ?

easy

A. IntegerField()

B. CharField(max_length=100)

C. DateField()

D. TextField()

Solution

1. Step 1: Understand the data type needed for a name

   A person's name is text, so a text-based field is needed.

2. Step 2: Choose the field with character limit

   CharField stores text with a max length, perfect for names.

3. Final Answer:

   CharField(max_length=100) -> Option B

4. Quick Check:

   Text with length limit = CharField(max_length=100) [OK]

Hint: Use CharField for text with max length limits [OK]

Common Mistakes:

• Using IntegerField for text data
• Using DateField for names
• Using TextField without length limit when limit is needed

2. Which of the following is the correct syntax to define an IntegerField named age in a Django model?

easy

A. age = models.CharField(max_length=3)

B. age = models.DateField()

C. age = models.IntegerField()

D. age = models.Integer()

Solution

1. Step 1: Identify the correct Django field for integers

   IntegerField is the correct field type for whole numbers.

2. Step 2: Check the syntax for defining the field

   It must be assigned as models.IntegerField() inside the model.

3. Final Answer:

   age = models.IntegerField() -> Option C

4. Quick Check:

   Integer field syntax = models.IntegerField() [OK]

Hint: Integer fields use models.IntegerField() exactly [OK]

Common Mistakes:

• Using models.Integer() which does not exist
• Using CharField for numbers
• Omitting parentheses after IntegerField

3. Given this Django model snippet:

class Event(models.Model):
    title = models.CharField(max_length=50)
    attendees = models.IntegerField()
    event_date = models.DateField()

What type of data will event_date store?

medium

A. Dates in YYYY-MM-DD format

B. Whole numbers representing attendees

C. Text strings up to 50 characters

D. Floating point numbers

Solution

1. Step 1: Identify the field type of event_date

   It is defined as models.DateField(), which stores dates.

2. Step 2: Understand the format stored by DateField

   DateField stores dates in a standard format like YYYY-MM-DD.

3. Final Answer:

   Dates in YYYY-MM-DD format -> Option A

4. Quick Check:

   DateField stores dates = Dates in YYYY-MM-DD format [OK]

Hint: DateField stores dates, not text or numbers [OK]

Common Mistakes:

• Confusing DateField with CharField
• Thinking DateField stores timestamps or datetime
• Assuming DateField stores numbers

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

class Product(models.Model):
    price = models.IntegerField(max_length=10)

medium

A. IntegerField does not accept max_length argument

B. Field name 'price' is invalid

C. IntegerField should be CharField here

D. Missing default value for price

Solution

1. Step 1: Check IntegerField arguments

   IntegerField does not support max_length; it's for CharField only.

2. Step 2: Confirm the error cause

   Using max_length with IntegerField causes a syntax or runtime error.

3. Final Answer:

   IntegerField does not accept max_length argument -> Option A

4. Quick Check:

   max_length only for CharField = IntegerField does not accept max_length argument [OK]

Hint: max_length is only for CharField, not IntegerField [OK]

Common Mistakes:

• Adding max_length to IntegerField
• Confusing field names as errors
• Thinking default value is mandatory

5. You want to create a Django model for a blog post with a title (max 200 chars), number of likes (whole number), and published date. Which field types should you use for title, likes, and published respectively?

hard

A. CharField(max_length=200), FloatField(), DateField()

B. TextField(), CharField(max_length=200), DateTimeField()

C. CharField(max_length=200), IntegerField(max_length=10), DateField()

D. CharField(max_length=200), IntegerField(), DateField()

Solution

1. Step 1: Choose field for title with character limit

   CharField with max_length=200 fits the title text limit.

2. Step 2: Choose field for likes as whole number

   IntegerField stores whole numbers like likes count.

3. Step 3: Choose field for published date

   DateField stores the date when the post was published.

4. Final Answer:

   CharField(max_length=200), IntegerField(), DateField() -> Option D

5. Quick Check:

   Title=text, Likes=integer, Date=date = CharField(max_length=200), IntegerField(), DateField() [OK]

Hint: Match field type to data: text, number, date [OK]

Common Mistakes:

• Using max_length on IntegerField
• Using FloatField for likes count
• Confusing DateField with DateTimeField