Inventory Management with JSON in Python

Inventory management is essential for any business that handles products or stock. It involves tracking the flow of goods to ensure adequate supply while avoiding overstocking or stockouts. This tutorial demonstrates how to create an inventory management system using JSON for data storage in Python.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data interchange format that's easy for humans to read and write. It uses key-value pairs similar to Python dictionaries and is widely used for data exchange between applications.

JSON Syntax

{
    "apple": {"price": 10, "quantity": 50},
    "banana": {"price": 5, "quantity": 30},
    "orange": {"price": 8, "quantity": 25}
}

JSON consists of key-value pairs enclosed in curly braces. Keys are always strings, and values can be strings, numbers, booleans, arrays, or nested objects.

Basic JSON Operations in Python

Python's built-in json module provides functions to work with JSON data ?

import json

# Sample inventory data
inventory_data = {
    "apple": {"price": 10, "quantity": 50},
    "banana": {"price": 5, "quantity": 30}
}

# Convert Python dict to JSON string
json_string = json.dumps(inventory_data, indent=2)
print("JSON String:")
print(json_string)

# Convert JSON string back to Python dict
parsed_data = json.loads(json_string)
print("\nParsed Data:")
print(parsed_data)

JSON String:
{
  "apple": {
    "price": 10,
    "quantity": 50
  },
  "banana": {
    "price": 5,
    "quantity": 30
  }
}

Parsed Data:
{'apple': {'price': 10, 'quantity': 50}, 'banana': {'price': 5, 'quantity': 30}}

Method 1: Simple Dictionary-Based Inventory

This approach uses Python's json module with a dictionary to manage inventory data ?

import json

# Initialize inventory
inventory = {
    "apple": {"price": 10, "quantity": 50},
    "banana": {"price": 5, "quantity": 30}
}

def add_item(name, price, quantity):
    inventory[name] = {"price": price, "quantity": quantity}
    print(f"Added {name} to inventory")

def remove_item(name):
    if name in inventory:
        del inventory[name]
        print(f"Removed {name} from inventory")
    else:
        print(f"Item {name} not found")

def display_inventory():
    print(f"{'Item':<15} {'Price':<10} {'Quantity':<10}")
    print("-" * 35)
    for item, data in inventory.items():
        print(f"{item:<15} {data['price']:<10} {data['quantity']:<10}")

def save_to_file(filename):
    with open(filename, 'w') as f:
        json.dump(inventory, f, indent=2)
    print(f"Inventory saved to {filename}")

# Test the functions
add_item("orange", 8, 25)
display_inventory()
print()
remove_item("banana")
display_inventory()

Added orange to inventory
Item            Price      Quantity  
-----------------------------------
apple           10         50        
banana          5          30        
orange          8          25        

Removed banana from inventory
Item            Price      Quantity  
-----------------------------------
apple           10         50        
orange          8          25        

Method 2: Object-Oriented Inventory Class

This approach uses a custom class to encapsulate inventory operations and data management ?

import json

class InventoryManager:
    def __init__(self):
        self.inventory = {}
    
    def add_item(self, name, price, quantity):
        self.inventory[name] = {"price": price, "quantity": quantity}
        return f"Added {name} to inventory"
    
    def remove_item(self, name):
        if name in self.inventory:
            del self.inventory[name]
            return f"Removed {name} from inventory"
        else:
            return f"Item {name} not found"
    
    def update_quantity(self, name, new_quantity):
        if name in self.inventory:
            self.inventory[name]["quantity"] = new_quantity
            return f"Updated {name} quantity to {new_quantity}"
        else:
            return f"Item {name} not found"
    
    def get_item_info(self, name):
        if name in self.inventory:
            return self.inventory[name]
        else:
            return None
    
    def display_inventory(self):
        if not self.inventory:
            return "Inventory is empty"
        
        result = f"{'Item':<15} {'Price':<10} {'Quantity':<10}\n"
        result += "-" * 35 + "\n"
        for item, data in self.inventory.items():
            result += f"{item:<15} ${data['price']:<9} {data['quantity']:<10}\n"
        return result
    
    def save_to_json(self, filename):
        with open(filename, 'w') as f:
            json.dump(self.inventory, f, indent=2)
        return f"Inventory saved to {filename}"
    
    def load_from_json(self, filename):
        try:
            with open(filename, 'r') as f:
                self.inventory = json.load(f)
            return f"Inventory loaded from {filename}"
        except FileNotFoundError:
            return f"File {filename} not found"

# Example usage
manager = InventoryManager()

# Add items
print(manager.add_item("laptop", 999, 10))
print(manager.add_item("mouse", 25, 50))
print(manager.add_item("keyboard", 75, 30))

# Display inventory
print("\nCurrent Inventory:")
print(manager.display_inventory())

# Update quantity
print(manager.update_quantity("laptop", 8))

# Get specific item info
laptop_info = manager.get_item_info("laptop")
print(f"\nLaptop info: {laptop_info}")

# Remove item
print(manager.remove_item("mouse"))

# Final inventory
print("\nFinal Inventory:")
print(manager.display_inventory())

Added laptop to inventory
Added mouse to inventory
Added keyboard to inventory

Current Inventory:
Item            Price      Quantity  
-----------------------------------
laptop          $999       10        
mouse           $25        50        
keyboard        $75        30        

Updated laptop quantity to 8

Laptop info: {'price': 999, 'quantity': 8}
Removed mouse from inventory

Final Inventory:
Item            Price      Quantity  
-----------------------------------
laptop          $999       8         
keyboard        $75        30        

Comparison

Key Features of JSON Inventory Management

• Persistence Data is stored in JSON files and survives program restarts

• Human-readable JSON format is easy to read and debug

• Cross-platform JSON works across different programming languages

• Lightweight Minimal overhead compared to databases

Conclusion

JSON provides an excellent solution for simple inventory management systems in Python. The dictionary approach works well for basic needs, while the class-based approach offers better organization and extensibility for larger applications. Both methods leverage JSON's simplicity and Python's built-in json module for effective data management.