Fix bug: user should not be able to set stock to negative numbers

[mw3155]

User description

Fixes #3

Add validation to prevent setting negative stock values in CatalogItem model, CatalogController, and CatalogService.

• CatalogItem Model:

  • Add validation attribute to AvailableStock property to ensure it cannot be set to negative values.

• CatalogController:

  • Add validation in Create action to check for negative stock values and add error message to the frontend.
  • Add validation in Edit action to check for negative stock values and add error message to the frontend.

• CatalogService:

  • Add validation in CreateCatalogItem method to check for negative stock values and throw an exception if the value is negative.
  • Add validation in UpdateCatalogItem method to check for negative stock values and throw an exception if the value is negative.

• Views:

  • Add error message display for negative stock values in Create.cshtml.
  • Add error message display for negative stock values in Edit.cshtml.

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PR Type

Bug fix, Enhancement

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Description

• Added validation to CatalogController to prevent setting negative stock values in both Create and Edit actions.
• Enhanced CatalogItem model with range validation to ensure AvailableStock cannot be negative.
• Updated CatalogService to throw exceptions for negative stock values in CreateCatalogItem and UpdateCatalogItem methods.
• Improved user feedback by adding validation message displays for negative stock values in Create.cshtml and Edit.cshtml views.

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Changes walkthrough 📝

	Relevant files
Bug fix	CatalogController.cs Add validation for negative stock values in CatalogController eShopOnWeb/eShop.MVC/Controllers/CatalogController.cs Added validation to prevent negative stock values in Create action. Added validation to prevent negative stock values in Edit action. +8/-0      CatalogService.cs Add exception handling for negative stock in CatalogService eShopOnWeb/eShop.MVC/Services/CatalogService.cs Added exception handling for negative stock values in CreateCatalogItem. Added exception handling for negative stock values in UpdateCatalogItem. +9/-1
Enhancement	CatalogItem.cs Add range validation to AvailableStock in CatalogItem model eShopOnWeb/eShop.MVC/Models/CatalogItem.cs Added range validation to AvailableStock to prevent negative values. +2/-1      Create.cshtml Display validation message for negative stock in Create view eShopOnWeb/eShop.MVC/Views/Catalog/Create.cshtml Added validation message display for negative stock values. +1/-0      Edit.cshtml Display validation message for negative stock in Edit view eShopOnWeb/eShop.MVC/Views/Catalog/Edit.cshtml Added validation message display for negative stock values. +1/-0

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PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis ✅ 3 - Fully compliant Compliant requirements: Added validation to prevent negative stock values Added error messages for negative stock input Implemented validation at model, controller, and service levels

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Redundant Validation Service-level validation might be redundant since model-level validation is already in place. Consider removing service validation to follow single responsibility principle. Redundant Validation Controller-level validation might be redundant since model-level validation is already in place. The ModelState.IsValid check would catch the Range validation error.

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
General	✅ Remove duplicate validation logic to maintain single source of truth for business rules Remove redundant validation in service layer since validation is already handled by model attributes and controller. This avoids duplicate validation logic and potential inconsistencies. eShopOnWeb/eShop.MVC/Services/CatalogService.cs [53-56] -if (catalogItem.AvailableStock < 0) -{ - throw new ArgumentException("Stock value cannot be negative."); -} +// Remove validation check as it's handled by model validation [Suggestion has been applied] Suggestion importance[1-10]: 8 Why: Valid suggestion to eliminate redundant validation logic, as the validation is already handled at the model and controller levels. This improves code maintainability and reduces the risk of inconsistent validation rules.	8
	Remove redundant manual validation in favor of attribute-based validation Remove manual ModelState validation since the Range attribute on AvailableStock property will automatically handle this validation. eShopOnWeb/eShop.MVC/Controllers/CatalogController.cs [66-69] -if (catalogItem.AvailableStock < 0) -{ - ModelState.AddModelError("AvailableStock", "Stock value cannot be negative."); -} +// Remove manual validation as it's handled by model attributes Apply this suggestion Suggestion importance[1-10]: 8 Why: Excellent suggestion to remove duplicate validation since the Range attribute on the model will automatically handle this validation. This simplifies the code and maintains validation logic in a single place.	8
	Use appropriate numeric type to enforce non-negative constraint at type level Consider using unsigned integer (uint) instead of int with Range validation to inherently prevent negative values at the type level. eShopOnWeb/eShop.MVC/Models/CatalogItem.cs [46-47] -[Range(0, int.MaxValue, ErrorMessage = "Stock value cannot be negative.")] -public int AvailableStock { get; set; } +public uint AvailableStock { get; set; } Apply this suggestion Suggestion importance[1-10]: 4 Why: While using uint would enforce non-negative values at the type level, it might introduce compatibility issues with existing code and database schema. The current Range validation approach is sufficient and more flexible.	4

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[qodo-code-review]

Suggestion: Remove duplicate validation logic to maintain single source of truth for business rules [General, importance: 8]

Suggested change

	if (catalogItem.AvailableStock < 0)
	{
	throw new ArgumentException("Stock value cannot be negative.");
	}
	// Remove validation check as it's handled by model validation