RE: Dynamic LINQ ITable

Hi EDBrian,

Based on your issue description, I think the main problem here is that if
you want to use a certain column property in expression, that property need
to be statically exists in the table class(you can not dynamically add it
at runtime, at least can not do it at LINQ level).

Therefore, IMO, what you need here is dynamically define and build a
certain table class(assembly) and referece the class in it. In .net, the
way to create type/assembly dynamically is using Reflection and CodeDom
feature:

#Reflection and Dynamic Classes
http://www.osix.net/modules/article/?id=126

#Dynamic building and execution of assembly using CodeDome & Reflection
http://www.c-sharpcorner.com/UploadFile/pradeep.tiwari/DynamicBuildingandExe
cutionOfAssemblyUsingCodeDomeAndReflection08212006072200AM/DynamicBuildingan
dExecutionOfAssemblyUsingCodeDomeAndReflection.aspx

Also, here I found a web article mentioned something combine CodeDom and
Linq:

#CodeDom extensions and dynamic LINQ (string/script to LINQ emitting)
http://igorshare.wordpress.com/2008/01/11/codedom-extensions-and-dynamic-lin
q-stringscript-to-linq-emitting/

Hope this helps some.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead



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--------------------
Reply-To: "EDBrian" <preport@xxxxxxxxxxxxxxxxx>
From: "EDBrian" <preport@xxxxxxxxxxxxxxxxx>
Subject: Dynamic LINQ ITable
Date: Fri, 18 Jan 2008 13:55:30 -0800


Problem: We enable our clients to create custom fields they wish to
collect.
We want to use Dynamic LINQ to query this table (Just one).
My initial post and suggestion(s) are here: http://shrinkster.com/tzp

So I have a class called "ClientTable". All tables have some common
fields,
but I need to add more at runtime.
Now I have a class that looks like:
--------------------
[Table(Name="ClientTable")]
public class ClientTable{
[Column(DbType = "VarChar(400) NOT NULL")]
public string FirstName { get; set; }
}
--------------------

Now this works great in dynamic LINQ when I do something like:
--------------------
Table<ClientTable> table = db.GetTable(typeof(ClientTable));
table.Where("FirstName == @0", "Bill");
--------------------

But if a client has a column in that table called "Age" I can't do
something
like:
--------------------
table.Where("Age > @0", 30);
--------------------
I get an error saying that "Age" doesn't exist, even though it exists in
the
database. If I add the one Age property it works fine (which is
understandable).
So now, how can I dynamically add properties to ClientTable class at
runtime?

Is there a way to do something like this:
--------------------
Table<ClientTable> table = db.GetTable(typeof(Facade.CreateDynamicType)))
as
Table<ClientTable>;
--------------------

As I'm sure you know the problem is the typeof(Facade.CreateDynamicType)
because "CreateDynamicType" is a property and not a class.
I've tried some quick tests by making the CreateDynamicType a method that
returns a Type and other stupid ideas that just didn't work.

Can something like this be done, should I pursue a solution to my problem
this way or should I just stick to a normal method like the:
Table<ClientTable> table = db.GetTable(typeof(ClientTable));
and then try to dynamically destory and create a new "ClientTable" object
at
runtime?

Can I delete a type then create a new one on the fly? Any suggestions?



.

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