必需的可为空的日期时间

Question

I recently started on a new project and came across the following.
I'm looking at a class Widget which has a property:

[Required]
public int? WidgetTypeId { get; set; }

I'm struggling to see how this makes sense; if the field is Required why would it be nullable? (I understand the answer may be "human error". I'm wondering if there is a legitimate reason for doing this.)

Data points:

• I haven't done an exhaustive analysis but the UI (the bits with which I am familiar at any rate) appears to require the field to be populated.
• There is a backing database table, and the database column in question is not nullable.

Answer 1

The main reason is prevent under posting hacks. Also it displays an empty value in the view instead of the default value.

If it is non nullable DefaultModelBinder initializes with default value 01/01/0001 thus no ModelState error is generated.

In your case if an attack omits the property on a request a ModelState error is generated.

Model Validation: Model Validation

Under Posting Problem: Under and over posting problems