Entity Framework Core patterns for .NET 10. Covers DbContext configuration, migrations workflow, interceptors, compiled queries, ExecuteUpdateAsync, ExecuteDeleteAsync, value converters, and query optimization. Load this skill when working with databases, writing queries, managing schema changes, or

EF Core (.NET 10) Core Principles 1. EF Core is the default ORM — Use it unless you have a specific reason not to (extreme perf, legacy DB without FK constraints). See ADR 003. 2. DbContext is a unit of work — Don't wrap it in another UoW abstraction. EF Core already implements Unit of Work and Repository patterns internally. 3. Queries should be projections — Use .Select() to project into DTOs instead of loading full entities. This avoids over fetching and N+1 issues. 4. Migrations are code — Treat them like any other source code. Review them, test them, never auto apply in production. Patterns DbContext Configuration Use IEntityTypeConfiguration<T to keep entity configs separate and discoverable. Registration Query Projections (Avoid Over Fetching) Pagination ExecuteUpdateAsync / ExecuteDeleteAsync Bulk operations that bypass change tracking for better performance. Interceptors Use interceptors for cross cutting concerns like audit trails and soft deletes. Compiled Queries Use for hot path queries that execute frequently with the same shape. Value Converters Migrations Workflow Global Query Filters Anti patterns Don't Wrap DbContext in a Repository Don't Use Lazy Loading Don't Use .ToListAsync() Then Filter in Memory Don't Forget to Await Async Methods Decision Guide Scenario Recommendation Standard CRUD DbContext with projections Bulk updates (100+ rows) ExecuteUpdateAsync / ExecuteDeleteAsync Hot path read query Compiled query Complex reporting query Raw SQL with FromSqlInterpolated or Dapper Audit trails SaveChangesInterceptor Multi tenancy Global query filter Soft deletes Global query filter + interceptor Strongly typed IDs Value converter Production migration Idempotent SQL script, never auto migrate

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