How can I make my string property nullable

Question

I want to make the Middle Name of person optional  I have been using C  net code first approach  For integer data type its easy just by using   operator to make in nullable  I am looking for a way to make my sting variable nullable  I tried to search but could not find the way to make it nullable   Below is my code  Please suggest me how to make it nullable   public class ChildrenInfo        Key      public int ChidrenID   get  set          Required       Display Name   First Name         StringLength 50 ErrorMessage   First Name cannot exceed more than 50 characters         RegularExpression     A-Z   a-z     ErrorMessage   Name cannot have special character numbers or space         Column  FName        public string CFName   get  set          Display Name   Middle Name         RegularExpression     A-Z   a-z     ErrorMessage   Middle Name cannot have special character numbers or space         StringLength 35 ErrorMessage   Middle Name cannot have more than 35 characters         Column  MName        public string  CMName   get  set

User · Answer

string type is a reference type  therefore it is nullable by default  You can only use Nullable lt T gt  with value types   public struct Nullable lt T gt  where T   struct   Which means that whatever type is replaced for the generic parameter  it must be a value type

User · Answer

It s been a while when the question has been asked and C  changed not much but became a bit better  Take a look Nullable reference types  C  reference  string notNull    quot Hello quot   string  nullable   default  notNull   nullable      null forgiveness  C  as a language a  quot bit quot  outdated from modern languages and became misleading  for instance in typescript  swift there s a  quot   quot  to clearly say it s a nullable type  be careful  It s pretty clear and it s awesome  C  doesn t didn t have this ability  as a result  a simple contract IPerson very misleading  As per C  FirstName and LastName could be null but is it true  is per business logic FirstName LastName really could be null  the answer is we don t know because C  doesn t have the ability to say it directly  interface IPerson     public string FirstName    public string LastName

User · Answer

System String is a reference type so you don t need to do anything like  Nullable lt string gt    It already has a null value  the null reference    string x   null     No problems here

User · Answer

String is a reference type and always nullable  you don t need to do anything special  Specifying that a type is nullable is necessary only for value types

User · Answer

string is by default Nullable  you don t need to do anything to make string Nullable

User · Answer

Strings are nullable in C  anyway because they are reference types  You can just use public string CMName   get  set    and you ll be able to set it to null

User · Answer

As others have pointed out  string is always nullable in C   I suspect you are asking the question because you are not able to leave the middle name as null or blank  I suspect the problem is with your validation attributes  most likely the RegEx  I m not able to fully parse RegEx in my head but I think your RegEx insists on the first character being present  I could be wrong - RegEx is hard  In any case  try commenting out your validation attributes and see if it works  then add them back in one at a time

User · Answer

It s not possible to make reference types Nullable  Only value types can be used in a Nullable structure  Appending a question mark to a value type name makes it nullable  These two lines are the same   int  a   null  Nullable lt int gt  a   null

User · Answer

You don t need to do anything  the Model Binding will pass null to property without any problem

User · Answer

C  8 0 is published now so you can make reference types nullable too  For this you have to add   nullable enable   Feature over your namespace  It is detailed here   For example something like this will work    nullable enable namespace TestCSharpEight     public class Developer         public string FullName   get  set        public string UserName   get  set         public Developer string fullName                FullName   fullName          UserName   null             Also you can have a look this nice article from John Skeet that explains details

[c#] How can I make my string property nullable?

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