<div>
Working with DateTime and looking for null is tricky; a DateTime instance cannot be null. &nbsp;So how do you check for null? 
 
You can check for &quot;reasonable&quot; dates... &nbsp;A modern anniversary is unlikely to be in the year 0001 which is what a &quot;null&quot; datetime will default to. 
 
With that in mind, I wrote a simple delegate that does the trick for me in my quick tests. &nbsp;Try this: 
 

<pre><code class="code-1 nolinks" id="code-20-39906830-1">Func&lt;DateTime, DateTime&gt; dateValidate = (x) =&gt;
{
 if( x.Year &lt; 1000 ){
 return new DateTime(1900, 1, 1); // Some default?
 }

 return Convert.ToDateTime(x);
}
</code></pre>
 
and change your linq above to: 

<pre><code class="code-10 nolinks" id="code-20-39906830-2">var inv = from e in _context.Customers 
 select new Model.Customer
 {
 CustomerId = e.CustomerId,
 CustomerName = e.CustomerName,
 Address = e.Address,
 contact1 = e.Contact1,
 ContactNo2 = e.Contact2, 
 DateOfBirth =dateValidate(e.DateOfBirth),
 Anniversary = dateValidate(e.Anniversary),
 
 };
</code></pre>
 
In my tests, I had the Func immediately above the linq statement - just for the sake of making things easy to play with. 
 
Good luck! 
 
(If you need help understanding the Func&lt;...&gt; ... expression, let me know; I can elaborate further if needed. 
 
[Edit] 
You can, of course, change the dateValidate Func to do something else if you need. &nbsp;Hopefully the above serves as an example as to how you might &quot;extend&quot; your linq to validate whatever you need validated.
</div>

<div>
Hi Tony O'Byrne, 
 
Thanks for the comment. 
 
In our table BirthDate and Anniversary values are null sometimes as it is optional for the users to fill. These fields can't be set to default. 
 
Also in class my dateofbirth and anniversary properties are of type datetime and nullable. 
I get your point for DateTime not nullable but in my case I can't set any default value, so I insert null when user leave it empty. 
My properties are defined like , 
public DateTime ? DateOfBirth{get;set;} 
 
What I need is some kind of below or any better way than this, 
 
if &nbsp;(!string.isNullOrEmpty(e.DateOfBirth.ToString()) 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; DateOfBirth =Convert.ToDateTime(e.DateOfBirth); 
 
Any way to do this?
</div>

Example of Linq with validation and null check on DateTime

customerTest.cs

<div>
Hi Thanks, 
 
&nbsp;Func&lt;DateTime?, DateTime?&gt; dateValidate = (x) =&gt; 
&nbsp; &nbsp; &nbsp; &nbsp; { 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (x == null) 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; { 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Return some default 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return null; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; } 
 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return Convert.ToDateTime(x); 
&nbsp; &nbsp; &nbsp; &nbsp; }; 
 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // &amp;&amp;&nbsp;e.Address!=null 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; var inv = from e in _context.Customers 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; select new Model.Customer 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; { 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; CustomerId = e.CustomerId, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; CustomerName = e.CustomerName, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Address = e.Address, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; contact1 = e.Contact1, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ContactNo2 = e.Contact2, 
 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; DateOfBirth = dateValidate(e.DateOfBirth), 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Anniversary = dateValidate(e.Anniversary), 
 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }; 
 
Now this line is showing error, 
dateValidate(e.DateOfBirth) --&gt;&gt;cannot implicitly convert type 'System.Datetime?' to 'System.DateTime'.An explicit conversion cast
</div>

<div>
My bad other two properties were not declared as nullable. 
 
Thank you very much for the quick and perfect solutions.
</div>

<div>
The dateValidate delegate is returning a nullable type that may be confusing the Customer class. 
 
You might need to update your Customer datastructure. &nbsp;Can you change the DateOfBirth and Anniversary types to &quot;DateTime?&quot; &nbsp;(Nullable DateTime)
</div>

<div>
You're welcome. &nbsp;Glad it worked out. :)
</div>

<div>
<div class="content wysiwyg-content">
Hello Experts, 
 
 
I am having below code, 
 
&nbsp;var inv = from e in _context.Customers &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; select new Model.Customer 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; { 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; CustomerId = e.CustomerId, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; CustomerName = e.CustomerName, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Address = e.Address, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; contact1 = e.Contact1, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ContactNo2 = e.Contact2, &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; DateOfBirth =Convert.ToDateTime(e.DateOfBirth), 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Anniversary = Convert.ToDateTime(e.Anniversary), 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }; 
 
Now DateOfBirth &amp;&nbsp;Anniversary both fields may come as NULL values from database as they are not madatory.How can I check this?
</div>
</div>

Hello Experts,


I am having below code,

 var inv = from e in _context.Customers                        
                      select new Model.Customer
                      {
                          CustomerId = e.CustomerId,
                          CustomerName = e.CustomerName,
                          Address = e.Address,
                          contact1 = e.Contact1,
                          ContactNo2 = e.Contact2,                        
                          DateOfBirth =Convert.ToDateTime(e.DateOfBirth),
                          Anniversary = Convert.ToDateTime(e.Anniversary),
                        
                      };

Now DateOfBirth & Anniversary both fields may come as NULL values from database as they are not madatory.How can I check this?

help with linq select

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