Fetch vs FetchMany in NHibernate Linq provider
NHibernate eager loading can be done using Fetch
and FetchMany
, as described in NHibernate Linq Eager Fetching on Mike Hadlow's blog.
What is the difference between these two methods and under what circumstance would each be used?
Fetch
should be used for references and FetchMany
for collections.
This is particularly important because only FetchMany
can be combined with ThenFetchMany
to fetch "grandchildren" collections.
Example:
session.Query<User>()
.FetchMany(u => u.Orders)
.ThenFetchMany(o => o.OrderItems)