Search and ordering in Django - Mini Project: Build & Apply

Search and Ordering in Django

📖 Scenario: You are building a simple Django app to display a list of books. Users want to search for books by title and order the results by price.

🎯 Goal: Create a Django view that filters books by a search term in the title and orders the results by price.

📋 What You'll Learn

Create a list of books as Django model instances

Add a search term variable to filter books by title

Use Django QuerySet filtering and ordering

Return the filtered and ordered books in the view

💡 Why This Matters

🌍 Real World

Filtering and ordering data is common in web apps to help users find and sort items like products or articles.

💼 Career

Understanding how to filter and order data is essential for backend and full-stack developers working with databases and APIs.

1

Create the initial list of books

Create a list called books with these dictionaries exactly: {'title': 'Django Basics', 'price': 30}, {'title': 'Advanced Django', 'price': 45}, {'title': 'Python for Beginners', 'price': 25}, {'title': 'Django and REST', 'price': 40}

Django

# Create the list of books with title and price
# Your code here

Hint

Use a list of dictionaries with keys 'title' and 'price'.

2

Add a search term variable

Create a variable called search_term and set it to the string 'Django'

Django

books = [
    {'title': 'Django Basics', 'price': 30},
    {'title': 'Advanced Django', 'price': 45},
    {'title': 'Python for Beginners', 'price': 25},
    {'title': 'Django and REST', 'price': 40}
]
# Create a variable search_term with value 'Django'
# Your code here

Hint

Set search_term to the exact string 'Django'.

3

Filter books by search term in title

Create a list called filtered_books that includes only books from books where search_term is in the book's title (case sensitive). Use a list comprehension.

Django

books = [
    {'title': 'Django Basics', 'price': 30},
    {'title': 'Advanced Django', 'price': 45},
    {'title': 'Python for Beginners', 'price': 25},
    {'title': 'Django and REST', 'price': 40}
]
search_term = 'Django'
# Filter books by search_term in title
# Your code here

Hint

Use a list comprehension with if search_term in book['title'].

4

Order filtered books by price

Create a list called ordered_books by sorting filtered_books by the price key in ascending order using the sorted() function and a lambda function.

Django

books = [
    {'title': 'Django Basics', 'price': 30},
    {'title': 'Advanced Django', 'price': 45},
    {'title': 'Python for Beginners', 'price': 25},
    {'title': 'Django and REST', 'price': 40}
]
search_term = 'Django'
filtered_books = [book for book in books if search_term in book['title']]
# Sort filtered_books by price ascending
# Your code here

Hint

Use sorted(filtered_books, key=lambda book: book['price']) to order by price.

Practice

1. What is the main purpose of adding search and ordering features in a Django ListView?

easy

A. To change the database schema automatically

B. To speed up the server response time

C. To disable pagination on the page

D. To let users find and sort data easily

Solution

1. Step 1: Understand the role of search and ordering

   Search and ordering help users locate specific data and arrange it in a preferred sequence.

2. Step 2: Identify the main benefit in a ListView context

   In Django ListView, these features improve user experience by making data easier to find and view in order.

3. Final Answer:

   To let users find and sort data easily -> Option D

4. Quick Check:

   Search and ordering = user-friendly data access [OK]

Hint: Search and ordering improve user data access quickly [OK]

Common Mistakes:

• Thinking search changes database structure
• Assuming ordering disables pagination
• Believing it speeds server without code changes

2. Which of the following is the correct way to override the get_queryset method in a Django ListView to add ordering by a field named name?

easy

A. def get_queryset(self): return self.queryset.order_by('name')

B. def get_queryset(self): return super().get_queryset().order_by('name')

C. def get_queryset(self): return self.objects.order_by('name')

D. def get_queryset(self): return Model.objects.order_by('name')

Solution

1. Step 1: Recall how to override get_queryset in ListView

   Use super() to get the base queryset, then apply ordering.

2. Step 2: Check each option for correct syntax and context

   def get_queryset(self): return super().get_queryset().order_by('name') correctly calls super() and orders by 'name'. Others misuse queryset or model references.

3. Final Answer:

   def get_queryset(self): return super().get_queryset().order_by('name') -> Option B

4. Quick Check:

   Use super() + order_by() = def get_queryset(self): return super().get_queryset().order_by('name') [OK]

Hint: Use super() to get base queryset before ordering [OK]

Common Mistakes:

• Using self.queryset without defining it
• Calling objects on self instead of model
• Not using super() in get_queryset override

3. Given this Django ListView code snippet, what will be the result of accessing the view with URL parameter ?search=apple&order=price?

class ProductListView(ListView):
    model = Product
    def get_queryset(self):
        qs = super().get_queryset()
        search = self.request.GET.get('search')
        order = self.request.GET.get('order')
        if search:
            qs = qs.filter(name__icontains=search)
        if order:
            qs = qs.order_by(order)
        return qs

medium

A. Products filtered to names containing 'apple' and ordered by price

B. All products ordered by price ignoring search

C. Products filtered by price containing 'apple'

D. Error because 'order' parameter is not validated

Solution

1. Step 1: Analyze filtering by 'search' parameter

   The code filters products where name contains 'apple' (case-insensitive).

2. Step 2: Analyze ordering by 'order' parameter

   The code orders the filtered queryset by the 'price' field.

3. Final Answer:

   Products filtered to names containing 'apple' and ordered by price -> Option A

4. Quick Check:

   Filter by search + order by price = Products filtered to names containing 'apple' and ordered by price [OK]

Hint: Filter first, then order queryset in get_queryset [OK]

Common Mistakes:

• Ignoring the search filter when order is present
• Confusing filter field with order field
• Assuming error without validation in this context

4. Identify the error in this Django ListView code that tries to add search and ordering:

class ItemListView(ListView):
    model = Item
    def get_queryset(self):
        qs = super().get_queryset()
        search = self.request.GET.get('search')
        if search:
            qs = qs.filter(name__icontains=search)
        order = self.request.GET.get('order')
        qs = qs.order_by(order)
        return qs

medium

A. Missing pagination in the view

B. Using filter with icontains instead of contains

C. Calling order_by without checking if 'order' is None

D. Not calling super() in get_queryset

Solution

1. Step 1: Check usage of order_by with 'order' parameter

   The code calls order_by(order) without verifying if order is None, causing error if no 'order' param.

2. Step 2: Verify other parts for correctness

   Filter with icontains is valid, super() is called, pagination is optional and not an error here.

3. Final Answer:

   Calling order_by without checking if 'order' is None -> Option C

4. Quick Check:

   order_by needs valid field or check [OK]

Hint: Check if order param exists before calling order_by [OK]

Common Mistakes:

• Assuming filter icontains is wrong
• Forgetting to call super() (not the case here)
• Confusing pagination with query errors

5. You want to implement a Django ListView that allows users to search products by name and order results by price or rating. You also want to prevent invalid ordering fields from causing errors. Which is the best way to implement get_queryset?

hard

A. Filter by search term, then order only if order param is in allowed list ['price', 'rating']

B. Filter by search term, order by any order param without validation

C. Order first by order param, then filter by search term

D. Ignore search and order, just return all products

Solution

1. Step 1: Understand the need for validation of ordering fields

   Allowing only specific fields prevents errors and security issues.

2. Step 2: Apply filtering before ordering and validate order param

   Filter products by search term, then order only if order param is in ['price', 'rating'].

3. Final Answer:

   Filter by search term, then order only if order param is in allowed list ['price', 'rating'] -> Option A

4. Quick Check:

   Validate order param before ordering = Filter by search term, then order only if order param is in allowed list ['price', 'rating'] [OK]

Hint: Validate order fields before ordering queryset [OK]

Common Mistakes:

• Ordering without checking allowed fields
• Ordering before filtering
• Ignoring search parameter completely