How to dynamically manipulate linq queries

Question

0.00/5 (No votes)

See more:

This is my code:

var ddt1 = dt.AsEnumerable()
     .GroupBy(r => r.Field<int>("ChartId"))
     .Select(g => new
     {
         ChartId = g.Key,
         SumData = g.Sum(r => r.Field<int>("YAxisData"))
     })
     .ToList();

I want to do some thing like this:

string funcVariable="  .GroupBy(r => r.Field<int>("ChartId"))
                     .Select(g => new
                     {
                         ChartId = g.Key,
                         SumData = g.Sum(r => r.Field<int>("YAxisData"))
                     })"
                var ddt1 = dt.AsEnumerable()
                   funcVariable
                     .ToList();

Please suggest

What I have tried:

if i use a variable, then variable tolist is considered as characters to list which is not correct. Please suggest the correct way.

Posted 15-Mar-17 1:32am

goshan2011

Updated 15-Mar-17 2:27am

Add a Solution

Comments

Karthik_Mahalingam 15-Mar-17 7:35am

Not possible.

Prateek Dalbehera 15-Mar-17 7:48am

Have not think of such but a nice idea, like "execute" used in sql server for dynamic sql queries. As of now, its not supported. MS should start researching on it!!!!

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2017-03-15T02:14:00

You can't do that directly with C# - the language does not support it.

You can do it; you can create code, compile, and run it from inside an app: How to programmatically compile code using C# compiler[^] but it's not a good solution for general purpose work - it's goign to be hard to maintain, hard to control, and unless you are very careful it effectively hands control of your application internals to the user.

I can't think of a good reason to do that that putting the Linq code in a method instead wouldn't be a better solution.

Graeme_Grant · Answer 2 · 2017-03-15T02:27:00

Solution 2

It is possible using Expression Class (System.Linq.Expressions)[^] however it is outside the scope of Q&A.

This article may help: Basics of LINQ & Lamda Expressions - Code Project[^]

Posted 15-Mar-17 2:27am

Graeme_Grant