Tag: ef-core

EF Core throws this when a client-evaluated piece of your query throws while EF evaluates it. Read InnerException, turn on EnableSensitiveDataLogging, and move the null check outside the lambda.

Move a key off IDENTITY and onto a SQL Server sequence in EF Core 11 with UseSequence: the exact SQL EF emits, why explicit key values suddenly work without IDENTITY_INSERT, the bigint sequence feeding an int column, and the gaps you have to design around.

A singleton cannot inject a DbContext, but it can inject IDbContextFactory<T>, because AddDbContextFactory registers the factory as a singleton by default. Create and dispose one context per call, never cache the instance.

Every way dotnet tool install --global dotnet-ef fails on the .NET 10 SDK, with the exact message and exit code for each: already installed, version not found, downgrade blocked, shim conflict, dead NuGet feed, and the runtime mismatch that only breaks after the install succeeds.

Use FromSql on a DbSet when the procedure returns full entity rows, Database.SqlQuery<T> when it returns a projection, and ExecuteSql when it returns nothing. Never chain a LINQ operator onto an EXEC, and never read an output parameter before the reader is disposed.

EF Core scaffolds RenameTable when you change the table name, but DropTable plus CreateTable when you rename the entity class. Here is how to tell the two apart, the ToTable trick that makes a class rename free, and the column-rename bug that silently swaps your data.

They are not alternatives. WebApplicationFactory boots your app, Testcontainers boots your dependencies. Measured on .NET SDK 10.0.201: a container fixture costs 1.7 s per class against 10 ms for SQLite, and a HasMaxLength(16) violation that Postgres rejects with 22001 is silently accepted by SQLite.

Add a rowversion concurrency token in EF Core 11: the [Timestamp] and IsRowVersion setup, the SQL EF actually emits, catching DbUpdateConcurrencyException, store-wins vs client-wins vs merge, disconnected APIs with ETags, and the five traps that silently disable the whole thing.

Store C# enums as readable strings instead of ints in EF Core 11: HasConversion, bulk configuration for every enum, the nvarchar(max) trap, the ordering gotcha, and how to migrate an existing int column.

Add Microsoft.EntityFrameworkCore.Design to the startup project that dotnet ef builds, not the project holding your DbContext, and pass -s in layered solutions.