How to pass "00:00:00" if value in timespan is null?

Question

I am trying to sum my timespan. My logic is working absolutely fine, he only problem is if value is NULL then my application breaks. I want to pass "00:00:00" as my time-span if value is NULL. My following code is not working:

@Model.Sum(x=> TimeSpan.Parse(x.Time ?? "00:00:00").Minutes)

X.Time is string and in my logic it could be NULL.If it is NULL, I want to replace it with 00:00:00

What am I doing wrong?

What is the type of `x.Time`? And are you sure you want `Minutes` rather than `TotalMinutes`? What flavour of LINQ is this - EF, LINQ to Objects, something else? Is `x` null, or is `x.Time` null? When you say it's "not working" - what exactly happens? — Jon Skeet, Apr 12 '18 at 06:38
if x.Time is null I want it to be "00:00:00" because the data in time field is in this format. — Syed Safeer Ul Hassan, Apr 12 '18 at 06:42
Timespan can't be null, it's a value type. I'm guessing `x.Time` is a string, but why should I guess that? Please [edit] your question to provide the information @DaisyShipton asked for. — Zohar Peled, Apr 12 '18 at 06:42
must be x`` since `string Time = null; Console.WriteLine(TimeSpan.Parse(Time ?? "00:00:00").Minutes);` runs fine. — wp78de, Apr 12 '18 at 06:51
try with "0.00:00:00" since that is the timespan format (d.hh:mm:ss) — Gvozden Kuzman, Apr 12 '18 at 06:52
@wp78de: Unless it's a matter of using EF or similar and that not handling `??` properly. Unfortunately we're still missing a lot of information. — Jon Skeet, Apr 12 '18 at 06:52
Yes It i string and it can be NULL. X is my Lambda Expression — Syed Safeer Ul Hassan, Apr 12 '18 at 06:53
@SyedSafeerUlHassan `x` is not your lambda expression, it is the first parameter to your expression. — Patrick Hofman, Apr 12 '18 at 07:04
The code presented in the OP works fine if `x.Time` is null. There must be something else going on here that we're not being told about. Perhaps `x` itself is null? — Matthew Watson, Apr 12 '18 at 07:59
I'm guessing that this would work: `Model.Sum(x => TimeSpan.Parse(x?.Time ?? "00:00:00").Minutes);` (assuming that `x` OR `x.Time` could be null). — Matthew Watson, Apr 12 '18 at 08:00

score 2 · Answer 1 · answered Apr 12 '18 at 06:52

2

I guess you want to sum the total of minutes, so you can simply check for null and add 0 to the total amount:

@Model.Sum(x=> !string.IsNullOrEmpty(x.Time) ? TimeSpan.Parse(x.Time).TotalMinutes : 0)

answered Apr 12 '18 at 06:52

Patrick Hofman

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I think your query is not performant. Instead of checking all values, filtering before will be more efficiant. – Coskun Ozogul Apr 12 '18 at 07:59
No, it has to filter either way. The performance difference is negligible. Did you run it? @CoskunOzogul – Patrick Hofman Apr 12 '18 at 08:02
1

@CoskunOzogul And it is not very nice to downvote the user that tried to help you on your answer. – Patrick Hofman Apr 12 '18 at 08:02
You are right for downvote, I am sorry. I upvoted. But for the performance story, it depends on the size of the list. It can be important. – Coskun Ozogul Apr 12 '18 at 08:04
No, my answer filters too, but in a single step. The worst thing happening is that it adds 0. The CLR must be smart enough to void that action. – Patrick Hofman Apr 12 '18 at 08:07

Coskun Ozogul · Answer 2 · 2018-04-12T07:58:05.393

1

Instead of checking all values null or not, you can filter before in order to have only not null values.

@Model.Where(x => !string.IsNullOrEmpty(x.Time)).Sum(x=> TimeSpan.Parse(x.Time).Minutes)

edited Apr 12 '18 at 07:58

answered Apr 12 '18 at 06:52

Coskun Ozogul

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It is a string, and string doesn't have a `HasValue` property. – Patrick Hofman Apr 12 '18 at 06:53
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`?? "00:00:00"` is useless here. – Patrick Hofman Apr 12 '18 at 06:54
Right, I removed it – Coskun Ozogul Apr 12 '18 at 06:55
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Please explain more than "what about this". What did you do? Why did it help? – Patrick Hofman Apr 12 '18 at 06:59

score 1 · Answer 3 · answered Apr 12 '18 at 06:53

The TimeSpan.Parse method expects a parameter in the form

[ws][-]{ d | [d.]hh:mm[:ss[.ff]] }[ws]

since 00:00:00 is a valid input string, I'm taking a wild guess here and say that it's not about null values, but rather the error occurs when your x.Time was set by DateTime.Now.ToString() etc. because in those cases you get the

System.FormatException: 'String was not recognized as a valid TimeSpan.'

Your code works perfectly fine for Time being null. Please make sure the other values are valid.

Matthew Watson · Answer 4 · 2018-04-12T08:16:51.103

The problem with your question is that from what you say, the code should work. For example, the following code works correctly:

using System;
using System.Collections.Generic;
using System.Linq;

namespace Demo
{
    class Test
    {
        public string Time;
    }

    class Program
    {
        static void Main()
        {
            var Model = new List<Test>
            {
                new Test{Time = "01:01:01"},
                // null, // Uncomment this line to make it crash.
                new Test{Time = null}, 
                new Test{Time = "02:02:02"}
            };

            int result = Model.Sum(x => TimeSpan.Parse(x.Time ?? "00:00:00").Minutes);

            Console.WriteLine(result);
        }
    }
}

Since you say an error is occurring, there must be something else going wrong. I think that the issue is that x itself is null.

We can demonstrate that possibility by uncommenting the indicated line. If you do that, the program will crash.

If that is indeed the problem, then the solution is very simple; just change the summation to:

int result = Model.Sum(x => TimeSpan.Parse(x?.Time ?? "00:00:00").Minutes);

After making that change, a null x will not make it crash.

Note that it may be slightly better to write:

int result = Model.Sum(x => x?.Time != null ? TimeSpan.Parse(x.Time).Minutes : 0 );

because then you avoid parsing "00:00:00" only to return zero (via .Minutes), but the difference is likely to be very marginal if any.

+1 nice answer, especially the part about the unknown exception. It's really hard to tell what the error is when it's not stated in the question; e.g. you and Pervez assume a `NullReferenceException`, I assume a `FormatException` but in the end, unless OP edit's their answer, we can never know. — Thomas Flinkow, Apr 12 '18 at 08:16
@ThomasFlinkow You're right - it could be a `FormatException`. The question is really a bit too iffy to answer, but hopefully one of these answers will elicit more information from the OP! — Matthew Watson, Apr 12 '18 at 08:17

score 0 · Answer 5 · answered Apr 12 '18 at 07:14

0

Your are getting a null exception because x is null. So when you call the property x.Time, it will throw a NullReferenceException. You can use the ternary operator to check if x is null

 @Model.Sum(x => TimeSpan.Parse(x == null ? "00:00:00" : x.Time).Minutes)

answered Apr 12 '18 at 07:14

Pervez Alam

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No, he is not getting a NRE. Nowhere in the question it says so. – Patrick Hofman Apr 12 '18 at 07:18

score 0 · Answer 6 · answered Sep 09 '19 at 07:35

0

Try this one

TimeSpan? variable = (TimeSpan?)null.

This value return null value.

answered Sep 09 '19 at 07:35

Raviteja V

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How to pass "00:00:00" if value in timespan is null?

6 Answers6