Removing Duplicate Recipes

Introduction: Keeping Your Recipe Data Clean

Welcome back! So far, you have learned how to build and use API endpoints to retrieve, search, and rate recipes in your cooking helper app. As your app grows and more recipes are added, it’s important to make sure your data stays clean and reliable. One common problem in real-world applications is duplicate data — when the same recipe appears more than once in your database. Duplicate recipes can confuse users, make search results messy, and even affect features like ratings and recommendations. In this lesson, you will learn how to identify and remove duplicate recipes from your application. This is an important step in keeping your app’s data accurate and user-friendly. By the end of this lesson, you’ll know how to find and safely delete duplicate recipes, making your cooking helper app more professional and enjoyable for users.

How Duplicate Recipes Happen

Before we look at the solution, let’s talk about how duplicate recipes can appear in your database. Sometimes, users might add the same recipe twice by mistake. Other times, small differences — like extra spaces or different capitalization — can make two recipes look different to a computer, even though they are the same to a person. For example, these two names would be considered duplicates by a human, but not always by a computer: "Chocolate Cake" " chocolate cake " In our project, we consider recipes to be duplicates if their names are the same when you ignore spaces at the beginning or end and treat uppercase and lowercase letters as the same. This is called normalizing the name.

Understanding the Duplicate Recipe Removal Process

Let’s break down how the duplicate recipe removal process works, step by step.

1. Connecting to Your App and Database

First, the solution needs to connect to your app and the database where your recipes are stored. This is done by setting up the correct environment and importing the necessary modules and models: Python import sys import os from collections import defaultdict CURRENT_DIR = os.path.dirname(os.path.abspath(__file__)) PROJECT_ROOT = os.path.abspath(os.path.join(CURRENT_DIR, "..", "cooking_helper")) if PROJECT_ROOT not in sys.path: os.chdir(PROJECT_ROOT) sys.path.insert(0, PROJECT_ROOT) from sqlalchemy.orm import Session from app.db.session import SessionLocal from app.db.models import Recipe The code sets up the environment so the application’s code can be found and used. The database session and the Recipe model are imported so the solution can work with your recipes.

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Python

def normalize_name(name: str) -> str:
    return name.strip().lower()

def normalize_name(name: str) -> str:
    return name.strip().lower()

Python

def find_duplicate_recipes(confirm: bool = True) -> None:
    session: Session = SessionLocal()
    try:
        all_recipes = session.query(Recipe).all()

        name_map: dict[str, list[Recipe]] = defaultdict(list)
        for recipe in all_recipes:
            key = normalize_name(recipe.name)
            name_map[key].append(recipe)

        duplicates = {name: recs for name, recs in name_map.items() if len(recs) > 1}

        if not duplicates:
            print("✅ No duplicate recipes found.")
            return

        print("⚠️ Duplicate recipes found:\n")
        for name, recs in duplicates.items():
            print(f"Recipe Name: {name}")
            for r in recs:
                print(f"  - ID: {r.id}, Ingredients: {len(r.ingredients)}")
            print()

def find_duplicate_recipes(confirm: bool = True) -> None:
    session: Session = SessionLocal()
    try:
        all_recipes = session.query(Recipe).all()

        name_map: dict[str, list[Recipe]] = defaultdict(list)
        for recipe in all_recipes:
            key = normalize_name(recipe.name)
            name_map[key].append(recipe)

        duplicates = {name: recs for name, recs in name_map.items() if len(recs) > 1}

        if not duplicates:
            print("✅ No duplicate recipes found.")
            return

        print("⚠️ Duplicate recipes found:\n")
        for name, recs in duplicates.items():
            print(f"Recipe Name: {name}")
            for r in recs:
                print(f"  - ID: {r.id}, Ingredients: {len(r.ingredients)}")
            print()

⚠️ Duplicate recipes found:

Recipe Name: chocolate cake
  - ID: 1, Ingredients: 5
  - ID: 7, Ingredients: 5

⚠️ Duplicate recipes found:

Recipe Name: chocolate cake
  - ID: 1, Ingredients: 5
  - ID: 7, Ingredients: 5

Python

        if confirm:
            choice = input("Do you want to delete duplicates and keep one entry for each? (y/N): ").strip().lower()
            if choice != 'y':
                print("Aborted. No changes made.")
                return

        for recs in duplicates.values():
            to_keep = recs[0]
            to_delete = recs[1:]
            for r in to_delete:
                session.delete(r)
        session.commit()
        print("✅ Duplicates removed.")
    except Exception as e:
        session.rollback()
        print("❌ Error:", e)
        raise
    finally:
        session.close()

        if confirm:
            choice = input("Do you want to delete duplicates and keep one entry for each? (y/N): ").strip().lower()
            if choice != 'y':
                print("Aborted. No changes made.")
                return

        for recs in duplicates.values():
            to_keep = recs[0]
            to_delete = recs[1:]
            for r in to_delete:
                session.delete(r)
        session.commit()
        print("✅ Duplicates removed.")
    except Exception as e:
        session.rollback()
        print("❌ Error:", e)
        raise
    finally:
        session.close()

Python

if __name__ == "__main__":
    find_duplicate_recipes(confirm=True)

if __name__ == "__main__":
    find_duplicate_recipes(confirm=True)

text

✅ No duplicate recipes found.

✅ No duplicate recipes found.

text

⚠️ Duplicate recipes found:

Recipe Name: chocolate cake
  - ID: 1, Ingredients: 5
  - ID: 7, Ingredients: 5

Do you want to delete duplicates and keep one entry for each? (y/N):

⚠️ Duplicate recipes found:

Recipe Name: chocolate cake
  - ID: 1, Ingredients: 5
  - ID: 7, Ingredients: 5

Do you want to delete duplicates and keep one entry for each? (y/N):

text

✅ Duplicates removed.

✅ Duplicates removed.

text

Aborted. No changes made.

Aborted. No changes made.

Python

def normalize_name(name: str) -> str:
    return name.strip().lower()

Python

def find_duplicate_recipes(confirm: bool = True) -> None:
    session: Session = SessionLocal()
    try:
        all_recipes = session.query(Recipe).all()

        name_map: dict[str, list[Recipe]] = defaultdict(list)
        for recipe in all_recipes:
            key = normalize_name(recipe.name)
            name_map[key].append(recipe)

        duplicates = {name: recs for name, recs in name_map.items() if len(recs) > 1}

        if not duplicates:
            print("✅ No duplicate recipes found.")
            return

        print("⚠️ Duplicate recipes found:\n")
        for name, recs in duplicates.items():
            print(f"Recipe Name: {name}")
            for r in recs:
                print(f"  - ID: {r.id}, Ingredients: {len(r.ingredients)}")
            print()

⚠️ Duplicate recipes found:

Recipe Name: chocolate cake
  - ID: 1, Ingredients: 5
  - ID: 7, Ingredients: 5

Python

        if confirm:
            choice = input("Do you want to delete duplicates and keep one entry for each? (y/N): ").strip().lower()
            if choice != 'y':
                print("Aborted. No changes made.")
                return

        for recs in duplicates.values():
            to_keep = recs[0]
            to_delete = recs[1:]
            for r in to_delete:
                session.delete(r)
        session.commit()
        print("✅ Duplicates removed.")
    except Exception as e:
        session.rollback()
        print("❌ Error:", e)
        raise
    finally:
        session.close()

Python

if __name__ == "__main__":
    find_duplicate_recipes(confirm=True)

text

✅ No duplicate recipes found.

text

⚠️ Duplicate recipes found:

Recipe Name: chocolate cake
  - ID: 1, Ingredients: 5
  - ID: 7, Ingredients: 5

Do you want to delete duplicates and keep one entry for each? (y/N):

text

✅ Duplicates removed.

text

Aborted. No changes made.

Introduction: Keeping Your Recipe Data Clean

How Duplicate Recipes Happen

Understanding the Duplicate Recipe Removal Process

1. Connecting to Your App and Database

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2. Normalizing Recipe Names

3. Finding and Listing Duplicates

4. Safely Removing Duplicates

5. Running the Duplicate Removal

Example: Running the Duplicate Removal

Summary and What’s Next