Query Data That Has Not Yet Been Persisted

Question

Hello everyone.  I am new to LINQ, and had a question about querying records that have been added to my data conxtext (via insertonsubmit) but not yet persisted to my sql database.

Here's the scenario:

I'm building a WPF application that handles basic case management.  During the course creating a case, a user can add multiple persons.  I would like to be able to add person objects to my data context and display the names of the newly added (but not yet inserted into the database) persons in a list box.

My current linq query to retrieve the person names will not return data unless it has been persisted to my database, which I understand is by design.  However, is there a way to query the records that have been added to my data context but not yet persisted to my database?

Answer 1

IEnumerable<Person> emp = dc.GetChangeSet().Inserts.Where(i => i.GetType() == typeof(Person)).Cast<Person>();

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Kristofer - Huagati Systems Co., Ltd.
Cool tools for Linq-to-SQL and Entity Framework:
huagati.com/dbmltools (add-in with new features for Visual Studio 2008's L2S and EF designers)
huagati.com/L2SProfiler (Query profiler for Linq-to-SQL and LLBLGen Pro)

Answer 2

Thank you!  That was exactly what I needed!

Answer 3

Kristofer's answer is correct, however it can be shortened using the OfType method , which will return an IEnumerable<T>:

dc.GetChangeSet().Inserts.OfType<Person>();

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Document my code? Why do you think it's called "code"?

Answer 4

Thank you both.  The next thing I will need to do is to join the entities in the change set to return some specific rows.  Is there a good reference out there for this type of thing that either of you can point me to?

Answer 5

What do you want to join them to? Something else in the change set, or something db-side?

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Kristofer - Huagati Systems Co., Ltd.
Cool tools for Linq-to-SQL and Entity Framework:
huagati.com/dbmltools (add-in with new features for Visual Studio 2008's L2S and EF designers)
huagati.com/L2SProfiler (Query profiler for Linq-to-SQL and LLBLGen Pro)