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Tag: ef-core

32 posts · Page 2 of 4

2026-05-26 ef-core dotnet-11 sql-server

EF Core 11 Preview 4: Temporal Table Period Columns Can Finally Be Real Properties

EF Core 11 Preview 4 drops the long-standing shadow-property restriction on SQL Server temporal tables. PeriodStart and PeriodEnd can now be regular CLR properties, configured with strongly-typed HasPeriodStart and HasPeriodEnd lambdas.

2026-05-23 comparison ef-core dapper

EF Core compiled queries vs raw SQL vs Dapper: which read path wins?

For read-heavy paths in .NET 11, plain EF Core with AsNoTracking is within ~5% of Dapper. Reach for compiled queries on a profiled single-row hot path, and Dapper only for the lowest latency or SQL LINQ can't express.

2026-05-21 comparison csharp linq

IEnumerable vs IAsyncEnumerable vs IQueryable in C#: which one should the method return?

Three sequence interfaces, three execution models. Use IQueryable when a database can translate the query, IAsyncEnumerable when the producer is async and you want to stream, IEnumerable for everything else in memory.

2026-05-20 comparison ef-core dapper

EF Core 11 vs Dapper for bulk inserts: real benchmark

For bulk inserts in .NET 11, neither EF Core nor Dapper wins. SqlBulkCopy does. This is the benchmark, the why, and the seat each tool deserves.

2026-05-14 errors csharp dotnet

Fix: A possible object cycle was detected

System.Text.Json refuses to serialize graphs with back-references. Set ReferenceHandler.IgnoreCycles, project to a DTO, or mark the back-pointer with [JsonIgnore]. Preserve is a last resort.

2026-05-14 errors csharp dotnet

Fix: SqlException: Timeout expired during EF Core migrations

Migrations use the design-time DbContext, not your runtime CommandTimeout. Set the timeout via UseSqlServer(o => o.CommandTimeout(...)), the connection string Command Timeout, or Database.SetCommandTimeout before Migrate().

2026-05-11 errors csharp dotnet

Fix: dotnet ef migrations add fails with 'Unable to create an object of type DbContext'

EF Core's design-time tools could not instantiate your DbContext. Either expose a host via WebApplication.CreateBuilder, point to the right startup project, or implement IDesignTimeDbContextFactory.

2026-05-07 errors csharp dotnet

Fix: The instance of entity type cannot be tracked because another instance with the same key value is already being tracked

EF Core 11 throws when two objects share a primary key inside one DbContext. Detach the old one or update it in place. AsNoTracking on the read prevents the collision.

2026-05-07 errors csharp dotnet

Fix: A second operation was started on this context instance before a previous operation completed

EF Core throws when two awaits run in parallel on the same DbContext. Await each call sequentially, or get a new DbContext per concurrent unit of work via IDbContextFactory.

2026-05-05 errors csharp dotnet

Fix: System.InvalidOperationException: No connection string named 'DefaultConnection' could be found

If GetConnectionString returns null in .NET 11, your appsettings.json is missing the key, not copied to the build output, or the wrong environment file is being selected. Three checks fix 95% of cases.