ASP.NET Core Web API Interview Question #121

When should an API use database transactions?

Dependency Injection, Services, EF Core, Async & Data Access Mid-Level Intermediate

Quick Interview Answer

Use a transaction when multiple database operations must succeed or fail as one atomic unit and the default SaveChanges transaction boundary is not sufficient. EF Core already wraps a single SaveChanges call in a transaction for providers that support transactions.

Detailed Explanation

Avoid keeping transactions open while waiting on slow external network calls because long transactions can increase locking and contention.

Code Example

await using var transaction =
    await _db.Database.BeginTransactionAsync(token);

try
{
    // Multiple database operations
    await _db.SaveChangesAsync(token);
    await transaction.CommitAsync(token);
}
catch
{
    await transaction.RollbackAsync(token);
    throw;
}