The xxx property on 'yyy' could not be set to a 'null' value. You must set this property to a non-null value of type 'DateTime'. Error

Question

Although my database-column allows null values I'm getting an error message:

The 'CreatedDateTime' property on 'Country' could not be set to a 'null' value. You must set this property to a non-null value of type 'DateTime'.

What goes wrong here and how an i solve this in my code?

Thanks.

My database table:

CREATE TABLE [dbo].[Country](
 [Id] [uniqueidentifier] NOT NULL,
 [Code] [char](2) NOT NULL,
 [CreatedDateTime] [datetime] NULL 
 CONSTRAINT [PK_Country_1] PRIMARY KEY CLUSTERED

My Country class:

private Guid id;
private string code;
private DateTime createdDateTime;
...

public Guid Id
get
{
return this.id;
}
set
{
this.id = value;
}

public string Code
{
   get
   {
      return this.code;
   }
   set
   {
      this.code = value;
   }
}

public DateTime CreatedDateTime
{           
  get
  {
     return this.createdDateTime;
  }
  set
  {
     this.createdDateTime = value;
  }
}
...

The 'CreatedDateTime' property on 'Country' could not be set to a 'null' value. You must set this property to a non-null value of type 'DateTime'.

Answer 1

Open the EDMX designer, find your Country entity, select the CreatedDateTime property, and set "Nullable" to True.  Obviously from your code, CreatedDateTime is a DateTime - not a Nullable<DateTime> as it would need to be.

Answer 2

Thanks but I'm using Code First (not edmx).

I suppose I should modify my code as follows?

private DateTime? createdDateTime;
...

public DateTime? CreatedDateTime
{
  get { return this.createdDateTime; }
  set { this.createdDateTime = value; }
}
...

Answer 3

Yes that is how you will want to code it. Make sure that if you have a nullable column in the database that you specify a nullable in the POCO object.

---

Devlin Liles http://twitter.com/devlinliles http://www.devlinliles.com/ If a post answers your question, please click "Mark As Answer" on that post and "Mark as Helpful".

Answer 4

ok thanks.

last question what's confusing to me: when mapping with code first (EF4.1 RC) you have the options: IsOptional() and IsRequired() when should they be used?

eg
...
this.Property(c => c.CreatedDateTime)
   .HasColumnName("CreatedDateTime")
   .IsOptional();

Thanks.

Answer 5

On properties of foreign keys you should mark these either optional or required based on referencing.

---

Devlin Liles http://twitter.com/devlinliles http://www.devlinliles.com/ If a post answers your question, please click "Mark As Answer" on that post and "Mark as Helpful".

Answer 6

Hi GuyD,

Welcome!

IsOptional() and IsRequired() are used to configure database column, IsOptional()----database column is null/IsRequired() column is not null.

I think the link here is help: http://blogs.msdn.com/b/adonet/archive/2010/12/06/ef-feature-ctp5-fluent-api-samples.aspx

Have a nice day.

---

Alan Chen[MSFT]
MSDN Community Support | Feedback to us
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