[Last Call] Learn about multicloud storage options and how to improve your company's cloud strategy. Register Now

x
?
Solved

LINQ syntax - where condition?

Posted on 2013-01-15
19
Medium Priority
?
457 Views
Last Modified: 2013-01-15
decimal dec = Convert.ToDecimal(_repairBids.Select(o => o.BidAmt == null ? 0 : o.BidAmt).Sum(o => o));


if I wanted to filter this by "o.Status = "Approved" so that only bid amounts that are approved get totalled...what would be the syntax?
0
Comment
Question by:Tom Knowlton
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 11
  • 4
  • 4
19 Comments
 
LVL 22

Expert Comment

by:p_davis
ID: 38780118
decimal dec = Convert.ToDecimal(_repairBids.Where(o.Status == "Approved").Select(o => o.BidAmt == null ? 0 : o.BidAmt).Sum(o => o));
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780162
That looks correct to me.

If you don't mind helping me out, I keep getting:

value cannot be null

I tried to make provisions for this by adding this:

o.BidAmt == null ? 0 : o.BidAmt

but I must either be doing that wrong or the problem is elsewhere...


decimal dec = Convert.ToDecimal(_repairBids.Where(o => o.BidStatus == "Approved").Select(o => o.BidAmt == null ? 0 : o.BidAmt).Sum(o => o));

Open in new window



cannot be null
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780175
Does this make sense?


decimal dec = Convert.ToDecimal(_repairBids.Where(o => o.BidStatus == "Approved").Where(o => o.BidAmt != null).Select(o => o.BidAmt).Sum(o => o));


can you do multiple "WHERE"'s like that?
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 
LVL 22

Expert Comment

by:p_davis
ID: 38780180
do you know what is actually null?

you can try to check every level of that  object for null

o=> o == null  && ....?

also is it possible that the bidstatus is null? you might want to check for null in the where clause as well.
0
 
LVL 22

Expert Comment

by:p_davis
ID: 38780187
you can combine those two where clauses into one with &&
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780200
null means "has never had a value" right?

[EDIT]

In other words, null is not 0, "0" or ""
0
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 38780216
I thought BidAmt was a string? You can't mix types when using the conditional operator. Change the zero to a string:

decimal dec = Convert.ToDecimal(_repairBids.Where(o.Status == "Approved").Select(o => o.BidAmt == null ? "0" : o.BidAmt).Sum(o => o));

Open in new window

0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780217
>>  also is it possible that the bidstatus is null?

I supposed it could happen.  Better to be safe.  I'll check on that...
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780228
>>>>I thought BidAmt was a string? You can't mix types when using the conditional operator. >>>>Change the zero to a string:


in one result it WAS indeed a string.


in another it is an actual decimal.


Let me recheck that....
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780251
This line compiles fine, but at runtime I still get the error:  value cannot be null

decimal dec = Convert.ToDecimal(_repairBids.Where(o => o.BidStatus == "Approved" && o.BidStatus != null && o.BidAmt != null).Select(o => o.BidAmt).Sum(o => o));

Open in new window



What am I missing?
0
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 38780252
For readability's sake, I'd suggest breaking that logic up a bit (once the issue is corrected):

decimal dec;

var sum = _repairBids.Where(o.Status == "Approved")
                     .Select(o => o.BidAmt ?? "0")
                     .Sum(o => o);

dec = Convert.ToDecimal(sum);

Open in new window

0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780257
Does it matter where the WHERE is called in the chain?

For example, does it matter if the WHERE is before the SELECT in LINQ?
0
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 38780262
It can matter, but I don't think it does in this case.

What is the type of BidAmt?
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780278
>>>What is the type of BidAmt?


It is:

decimal?

which I interpret to mean it can be a decimal value or a null value returned
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780299
NOTE:

The exception message, if it helps at all:

System.ArgumentNullException was unhandled by user code
  Message=Value cannot be null.
Parameter name: source
  Source=System.Core
  ParamName=source
  StackTrace:
       at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
       at Reo.ContentControls.RepairBidFormSummary.ReturnTot() in C:\R13\Reo\ContentControls\RepairBidFormSummary.ascx.cs:line 81
       at Reo.ContentControls.Preservation.FillRepairBid() in C:\R13\Reo\ContentControls\Preservation.ascx.cs:line 266
       at Reo.ContentControls.Preservation.FillPg() in C:\R13\Reo\ContentControls\Preservation.ascx.cs:line 113
       at Reo.ContentControls.Preservation.Page_Load(Object sender, EventArgs e) in C:\R13\Reo\ContentControls\Preservation.ascx.cs:line 68
       at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
       at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)
       at System.Web.UI.Control.OnLoad(EventArgs e)
       at System.Web.UI.Control.LoadRecursive()
       at System.Web.UI.Control.LoadRecursive()
       at System.Web.UI.Control.LoadRecursive()
       at System.Web.UI.Control.LoadRecursive()
       at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  InnerException: 

Open in new window

0
 
LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 1000 total points
ID: 38780446
which I interpret to mean it can be a decimal value or a null value returned
Correct.

Are you certain that _repairBids is not null when you get to that line?
0
 
LVL 22

Assisted Solution

by:p_davis
p_davis earned 1000 total points
ID: 38780451
Of it is nullable (?) Then check the hasvalue property on it in the vlauses
0
 
LVL 5

Author Comment

by:Tom Knowlton
ID: 38780481
>>>Are you certain that _repairBids is not null when you get to that line?

Good news!!

Yes...this was the case.  _repairBids was null.  The entire thing.

I guess I didn't realize I needed to re-get everything from the data context.


Here is my final code:


 public decimal ReturnTot()
        {
            decimal dec = 0;

            using (PreservationDataContext dc = new PreservationDataContext())
            {
                _repairBids = dc.Pres_RepairBidFormSummary_Get(this.RepairBidFormID, this.RepairBidFormSID).ToList<Pres_RepairBidFormSummary_GetResult>();

                if (_repairBids != null)
                {
                    dec = Convert.ToDecimal(_repairBids.Where(o => o.BidStatus == "Approved" && o.BidStatus != null && o.BidAmt != null).Select(o => o.BidAmt).Sum(o => o));
                }
            }
            
            return dec;            
        }

Open in new window

0
 
LVL 5

Author Closing Comment

by:Tom Knowlton
ID: 38780488
Nice work, all of you!
0

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
The article shows the basic steps of integrating an HTML theme template into an ASP.NET MVC project
Please read the paragraph below before following the instructions in the video — there are important caveats in the paragraph that I did not mention in the video. If your PaperPort 12 or PaperPort 14 is failing to start, or crashing, or hanging, …
Is your data getting by on basic protection measures? In today’s climate of debilitating malware and ransomware—like WannaCry—that may not be enough. You need to establish more than basics, like a recovery plan that protects both data and endpoints.…

650 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