Search and filter options in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Django queryset filter?

Given the model Book with fields title and author, what does this queryset return?

Book.objects.filter(title__icontains='django')

A All books with titles exactly equal to 'django'

B All books with titles containing 'django' ignoring case

C All books with authors containing 'django' ignoring case

D All books with titles starting with 'django' ignoring case

💡 Hint

Look at the double underscore and the 'icontains' part in the filter.

The filter title__icontains='django' returns all books where the title contains the substring 'django' regardless of case.

📝 Syntax

intermediate

Which option correctly filters books published after 2020?

Assuming Book has a published_year integer field, which queryset filters books published after 2020?

A Book.objects.filter(published_year__gt=2020)

B Book.objects.filter(published_year>2020)

C Book.objects.filter(published_year__after=2020)

D Book.objects.filter(published_year__gte=2020)

💡 Hint

Look for the correct Django field lookup for greater than.

The correct lookup for greater than is __gt. Option A uses it correctly.

🔧 Debug

advanced

Why does this filter raise an error?

What error does this code raise?

Book.objects.filter(title__icontains)

A TypeError: filter() missing required positional argument

B SyntaxError: invalid syntax

C TypeError: filter() missing 1 required positional argument: 'kwargs'

D ValueError: Cannot use empty lookup value

💡 Hint

Check the filter method call and its arguments.

The filter method requires keyword arguments with values. Omitting the value causes a TypeError about missing arguments.

❓ state_output

advanced

How many items are in the queryset after this filter?

If the database has 5 books with titles: ['Django Basics', 'Advanced Django', 'Flask Guide', 'Django Tips', 'Python Tricks'], what is the count of Book.objects.filter(title__icontains='django')?

A 5

B 2

C 4

D 3

💡 Hint

Count titles containing 'django' ignoring case.

Titles containing 'django' are 'Django Basics', 'Advanced Django', and 'Django Tips' — total 3.

🧠 Conceptual

expert

Which option best describes the difference between filter() and exclude()?

In Django querysets, what is the main difference between filter() and exclude() methods?

A <code>filter()</code> returns items matching conditions; <code>exclude()</code> returns items not matching conditions

B <code>filter()</code> modifies the database; <code>exclude()</code> only reads data

C <code>filter()</code> returns a list; <code>exclude()</code> returns a dictionary

D <code>filter()</code> works only with strings; <code>exclude()</code> works only with numbers

💡 Hint

Think about what each method keeps or removes from the results.

filter() keeps items matching the condition, while exclude() removes those matching the condition.

Practice

1. What does the Django ORM method filter() do when used with icontains in a query?

easy

A. It returns records where the specified field contains the given substring, case-insensitive.

B. It deletes records that contain the given substring in the specified field.

C. It updates records to include the given substring in the specified field.

D. It sorts records alphabetically based on the specified field.

Solution

1. Step 1: Understand filter() usage

   The filter() method in Django ORM is used to select records that match certain conditions.

2. Step 2: Understand icontains lookup

   icontains checks if a field contains a substring, ignoring case differences.

3. Final Answer:

   It returns records where the specified field contains the given substring, case-insensitive. -> Option A

4. Quick Check:

   filter() + icontains = case-insensitive substring search [OK]

Hint: Remember: filter() narrows results; icontains ignores case [OK]

Common Mistakes:

• Confusing filter() with delete()
• Thinking icontains is case-sensitive
• Assuming filter() modifies data
• Mixing filter() with sorting methods

2. Which of the following is the correct syntax to filter a Django model Book by title containing the word 'django' ignoring case?

easy

A. Book.objects.get(title__icontains='django')

B. Book.objects.filter(title.contains='django')

C. Book.objects.filter(title__contains='django')

D. Book.objects.filter(title__icontains='django')

Solution

1. Step 1: Identify correct field lookup syntax

   Django uses double underscores to separate field and lookup, so title__icontains is correct.

2. Step 2: Choose correct method for filtering multiple records

   filter() returns a queryset; get() returns a single object and may error if multiple matches.

3. Final Answer:

   Book.objects.filter(title__icontains='django') -> Option D

4. Quick Check:

   filter() + __icontains syntax = Book.objects.filter(title__icontains='django') [OK]

Hint: Use double underscores for lookups and filter() for multiple results [OK]

Common Mistakes:

• Using single underscore instead of double
• Using get() when multiple results expected
• Using contains instead of icontains for case-insensitive
• Using incorrect method names like contains

3. Given the following Django view code snippet, what will books contain if the URL query string is ?search=python?

def book_list(request):
    query = request.GET.get('search', '')
    books = Book.objects.filter(title__icontains=query)
    return render(request, 'books.html', {'books': books})

medium

A. All Book objects with titles containing 'python' ignoring case.

B. All Book objects with titles exactly equal to 'python'.

C. An empty queryset because 'search' is not a valid field.

D. All Book objects regardless of title.

Solution

1. Step 1: Extract query parameter from request

   The code gets the 'search' parameter from the URL query string, which is 'python'.

2. Step 2: Apply filter with icontains lookup

   The filter uses title__icontains='python', so it returns books with titles containing 'python' ignoring case.

3. Final Answer:

   All Book objects with titles containing 'python' ignoring case. -> Option A

4. Quick Check:

   GET param + icontains filter = All Book objects with titles containing 'python' ignoring case. [OK]

Hint: GET params filter queryset with icontains for partial match [OK]

Common Mistakes:

• Thinking filter matches exact text only
• Assuming empty query returns all results
• Confusing GET params with POST data
• Believing filter ignores the query parameter

4. Identify the error in this Django view code for filtering Product objects by a search term from the URL:

def product_search(request):
    term = request.GET['search']
    results = Product.objects.filter(name_icontains=term)
    return render(request, 'search.html', {'results': results})

medium

A. Using request.GET['search'] causes a syntax error.

B. The field lookup should use double underscores: name__icontains.

C. The filter method should be get() instead of filter().

D. The render function is missing the request parameter.

Solution

1. Step 1: Check field lookup syntax in filter()

   The code uses name_icontains, but Django requires double underscores between field and lookup: name__icontains.

2. Step 2: Verify other parts of the code

   Using request.GET['search'] is valid but may raise KeyError if missing; render() usage is correct with request parameter.

3. Final Answer:

   The field lookup should use double underscores: name__icontains. -> Option B

4. Quick Check:

   Field lookup syntax requires double underscores [OK]

Hint: Use double underscores for lookups like __icontains [OK]

Common Mistakes:

• Using single underscore in field lookups
• Confusing filter() with get()
• Forgetting to pass request to render()
• Assuming request.GET[] never raises errors

5. You want to build a Django view that filters Article objects by a search term in the title and also filters by a minimum number of views provided by the user. Which of the following code snippets correctly applies both filters using values from request.GET?

hard

A. query = request.GET['q']
min_views = request.GET['min_views']
articles = Article.objects.filter(title__icontains=query).filter(views__lte=min_views)

B. query = request.GET.get('q')
min_views = request.GET.get('min_views')
articles = Article.objects.filter(title__contains=query, views__gt=min_views)

C. query = request.GET.get('q', '')
min_views = int(request.GET.get('min_views', 0))
articles = Article.objects.filter(title__icontains=query, views__gte=min_views)

D. query = request.GET.get('q', '')
min_views = int(request.GET.get('min_views', 0))
articles = Article.objects.filter(title__icontains=query).exclude(views__lte=min_views)

Solution

1. Step 1: Extract and convert GET parameters safely

   Using get() with default values avoids errors. Converting min_views to int is necessary for numeric comparison.

2. Step 2: Apply combined filters correctly

   Using filter() with multiple conditions joined by commas applies AND logic. title__icontains=query and views__gte=min_views correctly filter by title substring and minimum views.

3. Final Answer:

   query = request.GET.get('q', '') min_views = int(request.GET.get('min_views', 0)) articles = Article.objects.filter(title__icontains=query, views__gte=min_views) -> Option C

4. Quick Check:

   Safe GET + combined filter with AND = query = request.GET.get('q', '') min_views = int(request.GET.get('min_views', 0)) articles = Article.objects.filter(title__icontains=query, views__gte=min_views) [OK]

Hint: Use filter() with multiple conditions and convert GET values properly [OK]

Common Mistakes:

• Not converting min_views to int before filtering
• Using filter() then filter() with conflicting conditions
• Using contains instead of icontains for case-insensitive search
• Using exclude() incorrectly to simulate greater than or equal