EF Core Expert Skill

Trigger On

• The user requests database modeling, writing Linq queries, or handling database migrations.
• The project contains a DbContext class or references the Microsoft.EntityFrameworkCore package.
• There is a need to optimize database access performance or solve N+1 query problems.
• The task involves complex data relationship design (one-to-many, many-to-many, inheritance mapping).

Workflow

1. Perceive (Model Awareness):
   • Check .csproj to identify the EF Core version and database provider.
   • Analyze DbContext and entity configurations to confirm whether the Fluent API pattern is adopted.
   • Identify the current state of Migrations.
2. Reason (Planning Phase):
   • Evaluate whether queries need .AsNoTracking() or .AsSplitQuery().
   • Determine whether custom interceptors are needed to handle audit fields.
   • Evaluate whether to use ExecuteUpdate/Delete (.NET 7+) for massive data updates.
3. Act (Execution Phase):
   • Write efficient and safe Linq queries.
   • Implement entity configuration classes (IEntityTypeConfiguration).
   • Create and execute database migration commands.
4. Validate (Standard Validation):
   • Check if the generated SQL meets performance expectations (avoiding full table scans).
   • Validate concurrency conflict handling logic.
   • Ensure all database accesses follow asynchronous patterns.

Feature Roadmap (.NET 6 - 10)

.NET 6 & 7 (Foundation)

• Split Queries: Solve the Cartesian product problem.
• Bulk Operations: Use ExecuteUpdate/Delete for high-performance updates.
• JSON Columns: Built-in JSON mapping support.
• Compiled Models: Reduce startup time for large models.

.NET 8 & 9 (Productivity)

• Primitive Collections: Use simple type collections in queries.
• HierarchyId: Support for SQL Server hierarchical data.
• Auto-compiled Queries: Further optimize the query compilation process.
• Complex Types: Better support for Value Objects.

.NET 10+ (Cutting Edge)

• Advanced Interceptors: More query lifecycle hooks.
• Optimized AOT Support: AOT pre-compilation optimization for cloud-native environments.

Coding Standards

• Fluent API Preference: Prioritize entity configuration classes over Data Annotations.
• Async Always: All I/O operations must be asynchronous.
• No-Tracking by Default: Read-only queries must always use .AsNoTracking().
• Naming: Entity names correspond to tables, foreign key names have clear semantics.

Deliver

• Optimized Linq Queries: Provide query code with the potential for high-performance SQL translation.
• Migration Scripts & Guidance: Provide correct migration commands and manual adjustment suggestions.
• Database Schema Design: Design normalized entity relationships based on business requirements.

Validate

• Ensure the provided code complies with EF Core performance best practices.
• Validate whether the code correctly handles Nulls and database constraints.
• Confirm database connection and resource release logic is correct (using using or Scoped DI).

Documentation

Official References

• Entity Framework Core Overview
• Performance Optimization in EF Core
• Supported Database Providers

Internal References

• EF Core Coding Style and Naming Conventions
• EF Core Anti-Patterns and Best Practices
• EF Core Modern Patterns Guide