Solved

Is there a way to write a Pivot() using a LINQ query against a DataTable?

Posted on 2010-11-26
5
731 Views
Last Modified: 2013-11-11
I've got a bit of data problem I'm trying to figure out.


Essentially, I'm dealing with an Entity/Attribute/Value type of schema,
similar to IDS. Currently, we're sitting on an Oracle backend, but will
eventually move to something new (NOSQL, postgres,...) So, rather than push
to work to the database using a command (pivot) that might or might not be
supported, we want to do the work in code.

So, this is where we are...
When I initially query the database, I can a dataset back in the form:
NOTE:: I will


ENTITY TYPES
-----------------
ENT_TYPE_ID  ENTID  ENTNAME
======================
1                      1         a1
1                      2         a2
1                      3         a3
1                      4         a4
2                      1         b1
2                      2         b2
2                      3         b3
2                      4         b4

NOTE:: Each ENT_TYPE_ID can have 1-N ENTIDs

ID  ENTID VAL
=============
1   1     w1
1   2     x1
1   3     y1
1   4     z1       I'd like this to map to a table looking like this:
2   1     w2
2   2     x2           (Cols) a1   a2   a3   a4
2   3     y2           ---------------------------          
2   4     z2                     w1   x1   y1   z1
3   1     w3                    w2   x2   y2   z2
3   2     x3                     w3   x3   y3   z3
3   3     y3                     w4   x4   y4   z4
3   4     z3
4   1     w4
4   2     x4
4   3     y4
4   4     z4

The datatable will become the datasource for an Infragistics UltraDataGrid.
Our columns & data set are pretty dynamic in nature.
We'd like to do this as officially as possible in C#.

In Flex/Actionscript (and I assume Java), there's the notion of creating a dynamic
object based on named/value pairs. This works well in decoding JSON objects.
I'm kind of trying to approximate this in C#.

The 1st thought is to go to an array of dictionaries: ISortedDictionary<key, val>.
Now the question becomes, how to get from that to a DataTable?
Even though I'm using an list of items, I don't think it'll be directly bindable.
Dictionary objects can't be directly used to bind as a data source to a grid (or list, etc).

What's the best way to massage the array/list of dictionaries into datatable?
I know I could do it the brain dead way of iterating..., but is there a slicker
better performing approach I can take?

I took a look @ Tuples in C# 4.0.  As near as I can tell , they won't work in my implementation.
I am/will be dealing with a dynamic number of entities (1->N). The system should respond & behave
accordingly when presented with any number of Entities (Ent IDs).

Is there a way to do this in LINQ? I've been able to google a bunch of examples, but they
all dealt with a fixed number of entities.  I only know the number of entities @ runtime, so I ve
need to create a LINQ query that can PIVOT() on a dynamic set of entities.

Can LINQ somehow provide a PIVOT solution like that?
 
Performance considerations could be an issue here. It's unclear to me what the volume of through put will be.

Any help would be greatly appreciated here...

Thanks,
JohnB



0
Comment
Question by:jxbma
  • 2
  • 2
5 Comments
 
LVL 41

Expert Comment

by:ralmada
ID: 34231712
0
 
LVL 1

Author Comment

by:jxbma
ID: 34232999
Unfortunately, these links do not help.
I know how to do a "Pivot()" when I have a fixed number of columns
and I know them @ compile time.

The real issue I'm trying to solve is how to write a LINQ query for a dynamic set of columns.
(I only know them @ run time...)
0
 
LVL 41

Accepted Solution

by:
ralmada earned 500 total points
ID: 34241021
0
 
LVL 21

Expert Comment

by:tovvenki
ID: 34259502
0
 
LVL 1

Author Closing Comment

by:jxbma
ID: 34264688
Winner, winner, chicken dinner!! This is awesome; exactly what I've been looking for. Creating an anonymous type is the way to go. (Dynamic class & JSON object)
0

Featured Post

Resolve Critical IT Incidents Fast

If your data, services or processes become compromised, your organization can suffer damage in just minutes and how fast you communicate during a major IT incident is everything. Learn how to immediately identify incidents & best practices to resolve them quickly and effectively.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Entity Framework is a powerful tool to help you interact with the DataBase but still doesn't help much when we have a Stored Procedure that returns more than one resultset. The solution takes some of out-of-the-box thinking; read on!
Calculating holidays and working days is a function that is often needed yet it is not one found within the Framework. This article presents one approach to building a working-day calculator for use in .NET.
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa…

713 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question