分配前检查value是否为null

Question

so I am creating a new object and setting its properties from other functions. I need to check if those are null before applying the values. How would I approach this?

Customer = new Customer (
     name = requestCall.Name, 
     age = requestCall.Age.ofType<DateTime>().DOB
    )

how would I check if requestCall.Age or requestCall.Name is not null before applying?

Answer 1

Depending on your scenario you can use ternary operator

name = requestCall.Name == null ? something : something_else

or null coalesce operator

name = requestCall.Name ?? something

Answer 2

Variant 1:

Customer = new Customer(
     name = requestCall.Name ?? "default name", 
     age = requestCall.Age == null ? (some default date) :  requestCall.Age.ofType<DateTime>().DOB
);

Variant 2:

Customer = requestCall == null ? null : new Customer(
     name = requestCall.Name, 
     age = requestCall.Age.ofType<DateTime>().DOB
);

Of course, you can use if and to my mind, it is better:

Customer customer;
if (requestCall != null)
{
    customer = new Customer();
    if (requestCall.Name != null)
    {
        customer.Name = requestCall.Name;
    }
    // etc.
}
else
{
    customer = null;
}

Answer 3

Just make a requestCall.IsValid() method (aptly named something that fits in with your usage) and use this to verify whether or not you are able to make a new customer.

I'd imagine the logic will grow as you determine other things that need to be added and this will reduce the amount of updating you'll have to do.

As a side note to this: You may wish to make a constructor that takes in a requestCall as a parameter.

Answer 4

try this

Customer = new Customer (
     name = requestCall.Name ?? string.Empty, 
     age = requestCall.Age.ofType<DateTime>().DOB ?? DateTime.Now
    )

Answer 5

Do it as

 requestCall.Name ?? "soome text", 

or !string.IsNullOrEmpty(requestCall.Name) ? requestCall.Name : "soome text" !string.IsNullOrEmpty(requestCall.Name) ? requestCall.Name : "soome text" ,

and check null for integer as

 `age = requestCall.Age == null ? (default) :  requestCall.Age.ofType<DateTime>().DOB`