FirstOrDefault call in entity framework is cached but database is changed

问题

I have a strange issue, which I haven't experienced before. I use Entity Framework to retrieve my records.

I have the following call:

 var dbOrganisation = repository.DbOrganisation.FirstOrDefault(c => c.Id == id);

I expect no caching of this call. So when I make this call, I expect it to query the database and retrieve the latest DbOrganisation object. But that is not what happens.

I call this method relatively two times relatively short time after eachother (~5-10 seconds). But in this period, a decimal value in this table, can be changed by some third party.

However, even though the value changes, the FirstOrDefault call retrieves the not updated version.

Example situation:

1. I make the FirstOrDefault call, and see the decimal value of the field Credits, is 50
2. A third party changes the Credits to 45
3. I make the FirstOrDefault call 10 seconds, later, but the DbOrganisation still have 50 in Credits

What am i doing wrong? I thought the FirstOrDefault call was not cached by default?

回答1:

You doing everything correct, that's just how EF works.

You can use .AsNoTracking() for you purposes:

var dbOrganisation = repository.DbOrganisation.AsNoTracking().FirstOrDefault(c => c.Id == id);

DbExtensions.AsNoTracking Method: Returns a new query where the entities returned will not be cached in the DbContext or ObjectContext.

来源：https://stackoverflow.com/questions/24340207/firstordefault-call-in-entity-framework-is-cached-but-database-is-changed