Commit Q Dev

[rducic]

ATX1110 PostgreSQL Migration Fixes

Summary

Fixed multiple compatibility issues when migrating Bob's Bookstore application from SQL Server to PostgreSQL.

Changes Made

1. ReferenceDataItem.cs - Missing Column Mapping

File: app/Bookstore.Domain/ReferenceData/ReferenceDataItem.cs
Issue: PostgresException: 42703: column r.DataType does not exist
Fix: Added missing [Column("datatype")] attribute to map DataType property to database column.

2. ApplicationDbContext.cs - Boolean Type Conversion

File: app/Bookstore.Data/ApplicationDbContext.cs
Issue: PostgresException: 42804: column "wanttobuy" is of type numeric but expression is of type boolean
Fix: Added value conversion for ShoppingCartItem.WantToBuy property to convert boolean to integer.

3. BookRepository.cs - Better Error Handling

File: app/Bookstore.Data/Repositories/BookRepository.cs
Issue: ArgumentNullException: Value cannot be null
Fix: Changed SingleAsync to FirstOrDefaultAsync with null check for better error messages.

4. AuthorsController.cs - SQL Server to EF Core Migration

File: app/Bookstore.Web/Controllers/AuthorsController.cs
Issues:

• SQL Server stored procedures don't exist in PostgreSQL
• SqlParameter incompatible with PostgreSQL (requires NpgsqlParameter)
• SQL Server syntax (DECLARE, EXEC, [dbo], FORMAT, DATEDIFF) not supported
• Methods returning null causing view errors

Fixes:

• Replaced stored procedure calls with EF Core operations
• Converted raw SQL queries to LINQ
• Return empty lists instead of null
• Fixed nullable DateTime handling

5. ProductsController.cs - Stored Procedure Removal

File: app/Bookstore.Web/Controllers/ProductsController.cs
Issue: PostgresException: 42601: syntax error at or near "["
Fix: Replaced SQL Server stored procedure [dbo].[uspGetProductData]() with EF Core query _context.Product.ToListAsync().

Root Cause

The application was originally designed for SQL Server but was migrated to PostgreSQL without updating:

• Database-specific SQL syntax
• Stored procedure dependencies
• Parameter types
• Column mappings
• Data type conversions

Solution Approach

Converted all database operations to use Entity Framework Core, which provides:

• Database-agnostic operations
• Automatic parameter handling
• Cross-platform compatibility
• Simplified maintenance

Files Modified

1. app/Bookstore.Domain/ReferenceData/ReferenceDataItem.cs
2. app/Bookstore.Data/ApplicationDbContext.cs
3. app/Bookstore.Data/Repositories/BookRepository.cs
4. app/Bookstore.Web/Controllers/AuthorsController.cs
5. app/Bookstore.Web/Controllers/ProductsController.cs

All changes maintain existing functionality while ensuring PostgreSQL compatibility.�

[rducic]

For list of full chenages and reason why they were necessary please see https://github.com/rducic/AtxBobsBookstore/blob/ATX1110-FIX/ATX1110-FIX-changes.md