Entity Framework Core Interview Questions
DbContext, migrations, LINQ to Entities, tracking.
- 20Questions with answers
- 3Difficulty levels
Questions (20)
Browse beginner, intermediate, and advanced questions with answers — hide them when you want to self-test.
How would you test code that uses Entity Framework Core in .NET?
Use unit tests with mocks or fakes for external dependencies, integration tests against a real database or message broker when appropriate, and contract tests for APIs. Entity Framework Core should have clear inputs/outputs so tests remain fast and deterministic.
What logging or monitoring would you add around Entity Framework Core?
Log structured events with correlation IDs, track latency and error rates, and alert on SLO breaches. For Entity Framework Core, capture enough context to reproduce failures without logging secrets such as passwords or tokens.
How does Entity Framework Core interact with authentication in .NET applications?
Auth often gates access to endpoints or resources that rely on Entity Framework Core. Apply least privilege, validate tokens or sessions at the boundary, and never trust client-side checks alone. Mention OAuth, JWT, or session cookies as appropriate to the stack.
What environment variables or config files typically control Entity Framework Core?
Separate config from code using environment-specific settings, secrets managers, and twelve-factor practices. Document required variables for Entity Framework Core so deployments to staging and production remain repeatable and auditable.
Describe a REST or HTTP endpoint design concern related to Entity Framework Core.
Consider idempotency, status codes, pagination, versioning, and error payloads. Entity Framework Core should not leak internal exceptions to clients; return consistent error shapes and document them in OpenAPI or similar specs.
What is a simple way to handle errors when Entity Framework Core fails in .NET?
Catch exceptions at appropriate layers, map them to user-safe messages, retry transient failures with backoff where suitable, and record failures for operators. Avoid swallowing errors silently—failed Entity Framework Core operations should be visible in logs and metrics.
What documentation would you consult when working with Entity Framework Core in .NET?
Use the official .NET docs for Entity Framework Core, language or framework references, and reputable community guides. Bookmark release notes and migration guides when upgrading versions, since Entity Framework Core behavior can change between releases.
What is a common beginner mistake when learning Entity Framework Core?
Copying snippets without understanding why Entity Framework Core works leads to fragile code. Beginners often skip error handling, tests, or edge cases. Slow down, trace execution step by step, and validate assumptions with small experiments.
How does Entity Framework Core fit into an ASP.NET Core request pipeline?
Describe where Entity Framework Core runs relative to middleware, endpoints, and DI. Mention hosting (Kestrel) and how configuration binds for Entity Framework Core.
Which C# language features commonly appear with Entity Framework Core?
async/await, records, nullable reference types, and LINQ. Show how they improve correctness for Entity Framework Core.
How do you unit test code that uses Entity Framework Core?
xUnit + Moq/NSubstitute, WebApplicationFactory for integration, and in-memory providers when appropriate. Keep Entity Framework Core tests deterministic.
What DI lifetime would you choose for a service that implements Entity Framework Core?
Singleton vs scoped vs transient depends on state and DbContext rules. Justify the lifetime for Entity Framework Core with a concrete example.
How does configuration (appsettings/env) control Entity Framework Core?
Options pattern, validation on start, and secrets outside source control. Document required settings for Entity Framework Core.
What logging practices apply when Entity Framework Core fails?
ILogger with structured properties, correlation IDs, and no secrets in logs. Map Entity Framework Core exceptions to problem details for APIs.
When should you use middleware vs filters vs endpoint filters for Entity Framework Core?
Middleware for cross-cutting pipeline concerns; filters for MVC/minimal APIs specifics. Pick the narrowest layer that fits Entity Framework Core.
How would you implement Entity Framework Core in a production .NET codebase?
Follow team conventions, split concerns into testable units, handle edge cases, and document assumptions. Review similar modules in the codebase, add observability, and ship incrementally with feature flags if Entity Framework Core is risky.
What are common pitfalls when scaling Entity Framework Core in .NET?
Watch for bottlenecks, shared state races, config drift, and unbounded resource usage. Load-test Entity Framework Core paths, set limits, and plan horizontal scaling or caching before traffic spikes.
Compare two approaches to Entity Framework Core in .NET and when to use each.
One approach optimizes simplicity and time-to-market; the other optimizes performance, flexibility, or compliance. Choose based on team skill, traffic, and maintenance horizon—there is rarely a single best answer for Entity Framework Core.
How do you debug a production issue involving Entity Framework Core?
Reproduce in staging, check logs/metrics/traces, narrow scope with binary search deploys, and write a postmortem. Fix Entity Framework Core root cause, add regression tests, and improve alerts so similar failures are caught earlier.
What code review feedback would you give on a Entity Framework Core pull request in .NET?
Check correctness, tests, naming, error handling, security, and performance. Ask whether Entity Framework Core belongs in this layer, if docs updated, and if rollback is safe.
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