Hi Eric,
From your description, I understand that the problem here is the default
generated update code won't help on your additional inserting (to a insert
only table), correct?
For such case, I think the directly generated LINQ update method may have
some limitation, it just focus on the original database table. If you want
some additional code logic when performing the update, I suggest you
consider the followign approaches:
1. LINQ DataContext class and Table mapped class have some partial methods
which you can define via your own code. For example, for the following like
LINQ class(IDE generated), it provide several partial methods:
===========================
[System.Data.Linq.Mapping.DatabaseAttribute(Name="t estdb")]
public partial class UpdateDCDataContext : System.Data.Linq.DataContext
{
private static System.Data.Linq.Mapping.MappingSource mappingSource = new
AttributeMappingSource();
#region Extensibility Method Definitions
partial void OnCreated();
partial void Insertedit_table(edit_table instance);
partial void Updateedit_table(edit_table instance);
partial void Deleteedit_table(edit_table instance);
...................
======================
we can implement any of them in our own code as below:
======================
public partial class UpdateDCDataContext : System.Data.Linq.DataContext
{
partial void Updateedit_table(edit_table instance)
{
MessageBox.Show("Updateedit_table");
//reference the updated instance here
}
}
====================
thus, when you perform update operation (via the datacontext's
SubmitChanges method), the above partial method will get executed. You can
put addtional code logic in that method(just like an updating event).
#Understanding the DataContext
http://blogs.msdn.com/charlie/archiv...-the-dataconte
xt.aspx
#LINQ to SQL Tips 8: How to (and why) create a partial class in the
designer to augment generated code
http://blogs.msdn.com/dinesh.kulkarn...to-sql-tips-8-
how-to-and-why-create-a-partial-class-in-the-designer-to-augment-generated-c
ode.aspx
2. Also, have you considered creating another database table(in database)
which contains the same columns fields(schema). Thus, you can add LINQ
class to perform updating against that table. And for the inserting, you
can create a server-side database trigger to insert a new record into the
"insert only table". This maybe a pure database side solution(not quite
LINQ involved).
3. Or maybe we can consider separate this updating approach out and use
dedicated SQL+ ADO.NET command based method to perform the updating. Just
like traditional ADO.NET code.
Sincerely,
Steven Cheng
Microsoft MSDN Online Support Lead
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--------------------
>From: =?Utf-8?B?RXJpYyBGYWxza2Vu?= <ef******@newsgroups.nospam>
Subject: LINQ-to-SQL in an insert-only DB scenario
Date: Fri, 22 Aug 2008 11:54:00 -0700
>
We’re storing our main entity in an insert only table which stores the
history of past revisions, but we’re facing problems with storing this
history as LINQ will only update the entity, and not reinsert it with a
different revision number.
Compounding the issue, we’ve also got an associated table storing
properties
>for our entities which is not revisioned, but we still want changes to the
children of our entity (additions, changes & removals) reflected in the
properties table when we insert the latest version of our entity.
MainObject{
string Name, //PK
string Path, //PK
int RevisionNum, //PK in DB
EntitySet<ChildObjectChildren
}
The main problem right now is that when Updating instances of our
MainObject, we need a new record to be stored in the DB. When we were
mapping
>the object to insert via a stored proceedure, the ChildObjects weren't
being
>processed. Once we took out the stored proceedures, everything started
working very nicely.
How can we get LINQ to insert new records as part of the update, but also
handle the child objects nicely?
--
Eric Falsken
Technical Evangelist: db4o
http://www.db4o.com
