Tag: ef-core

Owned entities carry a hidden key and reference identity that fights value objects. Here is how to map a value object as a complex type in EF Core 11, when to switch, and the gotchas.

EF Core throws FOREIGN KEY constraint failed because the parent still has dependents the database refuses to orphan. Load the children, make the relationship optional, or configure OnDelete.

EF Core throws this when AddDbContext never ran, ran after Build, or your context's constructor takes the wrong DbContextOptions. Register before Build and use DbContextOptions<YourContext>.

HasData seeds an entity with a store-generated key but no explicit value. Give every seed row a stable non-zero Id, or switch to UseSeeding for generated keys.

Replace Skip/Take with a WHERE clause that seeks past the last row you saw. Order by a fully unique key, carry the last row's values as a cursor, and EF Core 11 turns the next page into an index seek instead of an OFFSET scan.

Map a nested type to a single JSON column with ComplexProperty(...).ToJson(), let EF Core 11 store it in the native SQL Server 2025 json type, then query into it with LINQ that translates to JSON_VALUE, JSON_CONTAINS, and JSON_PATH_EXISTS.

Use AsNoTracking for read-only queries by default. Reach for AsNoTrackingWithIdentityResolution only when the result graph contains the same entity more than once and your code depends on getting a single shared instance back.

EF Core 11 Preview 5 ships the EF1004 analyzer. It flags ToAsyncEnumerable() on an IQueryable so you do not accidentally enumerate a database query synchronously inside an await foreach.

EF Core can't find a key for your type. Either name a property Id or {Type}Id, add [Key], call HasKey, or - if it is a view or raw SQL result - call HasNoKey.

EnableRetryOnFailure conflicts with BeginTransaction. Wrap the whole transaction in db.Database.CreateExecutionStrategy().ExecuteAsync(...) so it retries as one unit.