Entity Framework Pitfalls: Entity Refresh

After an entity is loaded by Entity Framework, it gets stored in its first level cache. After that, whenever EF executes a query that returns this entity, identified by its primary key, EF always returns the cached entry, and makes no attempt to see if the cached data (the rest of the properties) is still up to date with that returned from the query. This feature is common to other ORMs, but it may result in unexpected behavior – we cannot rely on the state of a loaded entity if the database can change by other processes..

The solution for EF pre-Core is either:

  • Remove (evict) the entity from first level cache, by marking it as detached, when we want it to be reloaded from the database:
MyEntity e = ...;
ctx.Entry(e).State = EntityState.Detached;
  • Explicitly ask for it to be reloaded:
MyEntity e = ...;

In EF Core, there is no Reload method – although I did write an implementation for it –, so the only option is to detach the entity from the context.



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