How to set null to a GUID property

Question

I have an object of type Employee which has a Guid property  I know if I want to set to null I must to define my type property as nullable Nullable lt Guid gt  prop or Guid  prop   But in my case I m not able to change the type of the prop  so it will remains as Guid type and my colleague and I we don t want to use the Guid Empty   Is there a way to set my property as null or string empty in order to restablish the field in the database as null   I have a mechanism to transform from string empty to null but I will change many things if the would change to accept a empty guid to null   Any help please

User · Answer

Since  Guid  is not nullable  use  Guid Empty  as default value

User · Answer

Choose your poison - if you can t change the type of the property to be nullable then you re going to have to use a  magic  value to represent NULL   Guid Empty seems as good as any unless you have some specific reason for not wanting to use it   A second choice would be  Guid Parse  ffffffff-ffff-ffff-ffff-ffffffffffff   but that s a lot uglier IMHO

User · Answer

extrac Guid values from database functions        region GUID      public static Guid GGuid SqlDataReader reader  string field                try                       return reader field     DBNull Value   Guid Empty    Guid reader field                     catch   return Guid Empty               public static Guid GGuid SqlDataReader reader  int ordinal   0                try                       return reader ordinal     DBNull Value   Guid Empty    Guid reader ordinal                     catch   return Guid Empty               public static Guid  NGuid SqlDataReader reader  string field                try                       if  reader field     DBNull Value  return  Guid  null  else return  Guid reader field                     catch   return  Guid  null               public static Guid  NGuid SqlDataReader reader  int ordinal   0                try                       if  reader ordinal     DBNull Value  return  Guid  null  else return  Guid reader ordinal                     catch   return  Guid  null                endregion

User · Answer

you can make guid variable to accept null first using   operator then you use Guid Empty or typecast it to null using  Guid  null   eg    Guid  id   Guid Empty    or    Guid  id     Guid  null

User · Answer

Is there a way to set my property as null or string empty in order to restablish the field in the database as null    No  Because it s non-nullable  If you want it to be nullable  you have to use Nullable lt Guid gt  - if you didn t  there d be no point in having Nullable lt T gt  to start with  You ve got a fundamental issue here - which you actually know  given your first paragraph  You ve said   I know if I want to achieve A  I must do B - but I want to achieve A without doing B   That s impossible by definition   The closest you can get is to use one specific GUID to stand in for a null value - Guid Empty  also available as default Guid  where appropriate  e g  for the default value of an optional parameter  being the obvious candidate  but one you ve rejected for unspecified reasons

User · Answer

I think this is the correct way   Guid filed   Guid Empty

User · Answer

You can use typeof Guid    00000000-0000-0000-0000-000000000000  for DefaultValue of the property

User · Answer

Guid  myGuidVar    Guid  null    It could be  Unnecessary casting not required   Guid  myGuidVar   null

[c#] How to set null to a GUID property

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