Inventory Management System

A full-stack inventory management application built with ASP.NET (C#), React, and PostgreSQL. This app supports user registration and login, secure inventory tracking, item categorization, and a weighted average inventory valuation method.

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Tech Stack

• Frontend: React (Vite)
• Backend: ASP.NET Core Web API
• Database: PostgreSQL
• Authentication: JWT-based
• ORM: Entity Framework Core

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Database Structure & Relationships

User

Stores registered users and their associated data.

Field	Type
Id	int
FirstName	string
LastName	string
Username	string
Email	string
HashedPassword	string
CreatedAt	DateTime
Token	string
RefreshToken	string
RefreshTokenExpiryDate	DateTime

Relationships:

• One User -> Many Inventories
• One User -> Many Items
• One User -> Many Units
• One User -> Many RecentActivities

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Inventory

Represents a collection of items owned by a user.

Field	Type
Id	int
Title	string
UserId	int
InventoryTypeId	int

Relationships:

• Many Inventories -> One User
• Many Inventories -> One InventoryType
• One Inventory -> Many Items
• One Inventory -> Many Units

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Item

Represents a specific item in an inventory.

Field	Type
Id	int
Name	string
Tag	string
CreatedAt	DateOnly
InventoryId	int
UserId	int

Relationships:

• Many Items -> One Inventory
• Many Items -> One User

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Unit

Defines units of measurement for inventories and items.

Field	Type
Id	int
InventoryUnit	string
ItemUnit	int
UserId	int

Relationships:

• One User -> One Unit

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RecentActivity

Tracks user actions.

Field	Type
Id	int
Request	string
Type	string
UserId	int

Relationships:

• Many RecentActivities -> One User

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InventoryValuation (Weighted Average)

Tracks monthly inventory valuation using the weighted average method.

Field	Type
Id	int
InventoryId	int
UserId	int
Period	string
UnitsPurchased	int
TotalPurchaseCost	decimal
UnitsSold	int
UnitsRemaining	int
WeightedAverage	decimal
ClosingStock	decimal
CreatedAt	DateOnly

Scenario Example:

• Buy: 10 units @ R100 = R1000
• Buy: 20 units @ R200 = R2000
• Total: 30 units, R3000
• Weighted Avg = 3000 / 30 = R133.33
• Sold: 5 units
• Remaining = 25 units
• Closing Stock = 25 * 133.33 = R3333.25

Relationships:

• Many InventoryValuation -> One Inventory
• Many InventoryValuation -> One User

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Security

• JWT Authentication
• Password Hashing
• Refresh Tokens
• Extendable Role-based Access

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Features

• User Registration & Login
• Add/Update/Delete Inventories and Items
• Categorize Inventories
• Track Activity (CRUD)
• Unit Customization
• Weighted Average Inventory Valuation
• Secure APIs