Entity Framework中DbEntityEntry.Property方法是否使用反射？

Great question—let’s unpack how EF Core handles this under the hood to clear up your confusion.

First, let’s confirm @gertarnold’s point: when you call entityEntry.Property("InsertedBy"), EF Core does NOT use reflection to locate the property. Here’s why:

When you build your EF Core model (either via fluent API, data annotations, or convention), EF Core generates a detailed set of metadata for every entity and property. This metadata includes things like property names, types, and most importantly, pre-compiled accessor delegates for reading/writing property values. When you call Property("InsertedBy"), EF Core just looks up the corresponding IProperty entry from this pre-built metadata cache—no reflection involved here.

Now, to your core question: does setting the property value later require reflection? The short answer is almost never, in regular usage:

• For standard entity types (the ones you define in your code), EF Core generates compiled delegates at model build time. These are essentially lightweight IL-based functions that directly set or get the property value, skipping reflection entirely. When you do entityEntry.Property("InsertedBy").CurrentValue = "yourUser";, you’re invoking this pre-generated delegate, not using PropertyInfo.SetValue or similar reflection methods.
• There are edge cases where EF Core might fall back to reflection—like if you’re working with dynamically generated entity types, or if you have highly custom property access that can’t be compiled into a delegate. But these are rare exceptions, not the default behavior.

If you dug into the source code, you might have noticed classes like CompiledPropertyAccessor<TEntity, TProperty> or methods that reference PropertyAccessors—these are the pieces that handle the non-reflective value access. EF Core invests a lot in these compiled accessors because reflection is relatively slow, and avoiding it is a key performance optimization.

So to wrap up: @gertarnold is correct on both counts. entityEntry.Property() uses EF’s pre-built metadata to find the property, and setting the value uses compiled accessors (not reflection) in all normal scenarios.

内容的提问来源于stack exchange，提问作者CodingYoshi