SourceGuild Backend — Enterprise E-Learning & Course Platform API

SourceGuild is a high-performance, domain-driven e-learning backend engineered with ASP.NET Core. It provides secure, scalable RESTful APIs for course authoring, hierarchical section/lesson curricula, polymorphic multimedia content delivery, role-based student enrollments, progress tracking, and reviews.

The architecture has been refactored and modernized to strictly enforce Domain-Driven Design (DDD) Aggregate Boundaries, Vertical Slice Feature Handlers, the Result Pattern (eliminating exception-based flow control), zero-allocation static compile-time mappings, and containerized persistence using Microsoft SQL Server 2022.

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🏛️ Architecture & Solution Layout

The solution adopts modern enterprise standards, utilizing .slnx solution format, Clean Architecture layer boundaries, and Feature-driven organization:

SourceGuild/
├── src/
│   ├── SourceGuild.Domain/          # Pure Domain layer: Rich Aggregate Roots, Value Objects, Enums, Result Pattern
│   ├── SourceGuild.Application/     # Vertical Slices / Feature Handlers, DTOs, FluentValidation, Static Mappings
│   ├── SourceGuild.Infrastructure/  # EF Core DbContext, Split-Query Repositories, Identity JWT, Data Seeders
│   └── SourceGuild.API/             # ASP.NET Core Controllers, RFC 7807 ProblemDetails, OpenAPI/Swagger Docs
├── tests/
│   └── SourceGuild.Tests/           # Automated Test Suite: 20 Unit & Feature Tests (xUnit + Moq + FluentAssertions)
├── docs/                            # Docs-as-Code: PlantUML Domain Models, Logical ERD, C4 Diagrams, Architecture Roadmap
└── scripts/                         # DevOps automation: setup-secrets.sh, run-migrations.sh

Key Architectural Highlights

1. Rich Aggregate Roots vs. Anemic Domain:
   • Course acts as the strict Aggregate Root protecting all consistency boundaries for its child entities (Section, Lesson, ContentBlock).
   • Mutating child entities, re-indexing orders, or altering lifecycle states (Draft $\to$ Published) is strictly encapsulated within the aggregate root, eliminating orphan records.
2. Result Pattern & RFC 7807 ProblemDetails:
   • Replaced performance-heavy runtime exceptions (ServiceExceptions) with an explicit, zero-dependency Result<T> and domain Error record pattern.
   • ResultExtensions dynamically maps domain errors (Error.NotFound, Error.Validation, Error.Conflict) to standard HTTP ProblemDetails (404, 400, 409, 401, 403).
3. Zero-Allocation Compile-Time Mappings:
   • Completely eliminated AutoMapper and its reflection overhead in favor of static extension methods (MappingExtensions.ToDto()) utilizing C# pattern matching for polymorphic content blocks (TextContent, VideoContent), ensuring full Native AOT readiness.
4. EF Core Query Optimization:
   • Configured QuerySplittingBehavior.SplitQuery to eliminate Cartesian explosions when querying deep aggregate graphs (Course $\to$ Sections $\to$ Lessons $\to$ ContentBlocks).
5. Security & Secrets Governance:
   • Zero hardcoded credentials. All connection strings, SA passwords, and JWT private keys are resolved dynamically via dotnet user-secrets in development and parameterized .env files for Docker.

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🛠️ Technology Stack

Concern	Technology / Pattern
Language & Runtime	C# 14 / .NET 10.0 SDK
Architectural Style	Domain-Driven Design (DDD) + Vertical Slice Architecture
Web API & Routing	ASP.NET Core Controllers with OpenAPI / Swagger XML Documentation
Authentication & IAM	ASP.NET Core Identity + JWT Bearer Tokens (Role-Based Access Control)
ORM & Data Access	Entity Framework Core
Database Engine	Microsoft SQL Server 2022 (Linux Container via Docker Compose)
Validation & Error Handling	FluentValidation + Functional Result Pattern (Result<T>, Error)
Testing Frameworks	xUnit, Moq 4.20, FluentAssertions
Documentation & Tooling	PlantUML, Docker Compose, Shell Automation

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🚀 Getting Started

Prerequisites

• .NET 10.0 SDK
• Docker Engine & Docker Compose

1. Clone the repository

git clone https://github.com/Novav20/source-guild-backend.git
cd source-guild-backend

2. Configure Environment & Start SQL Server

# Copy the environment template
cp .env.example .env

# Start SQL Server 2022 container on host port 1434 (configured in .env)
docker compose up -d

3. Initialize User Secrets

# Automated secrets configuration script
./scripts/setup-secrets.sh

4. Apply Database Migrations & Seed Data

# Run automated interactive migration script (Option 1)
./scripts/run-migrations.sh

The database will be created and automatically populated with realistic test data (Instructors, Students, Categories, Courses with full curricula, and Reviews).

5. Run the API

dotnet run --project src/SourceGuild.API

Navigate to http://localhost:5037/swagger to explore and execute the interactive OpenAPI specification.

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🧪 Running Automated Tests

Run the complete test suite (Domain Aggregate Invariants & Application Feature Handlers):

dotnet test

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📖 Architecture & Design Documentation

Comprehensive technical diagrams and evolution roadmaps are available in the docs/ folder:

• Domain Model Class Diagram (DDD)
• Logical Entity-Relationship Diagram (ERD)
• Course Enrollment Sequence Diagram
• Content Blocks Architectural Roadmap

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📄 License

This project is open-source and available under the MIT License.