Ultimately, they are just a generic struct with a bool flag – except with special boxing rules. Because structs are (by default) initialized to zero, the bool defaults to false (no value): public struct Nullable<T> where T : struct { private readonly T value; private readonly bool hasValue; public Nullable(T value) { this.value = value; … Read more
I think you need to prefix the nil=”true” with a namespace in order for XmlSerializer to deserialise to null. MSDN on xsi:nil <?xml version=”1.0″ encoding=”UTF-8″?> <entities xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance” xsi:type=”array”> <entity> <id xsi:type=”integer”>1</id> <name>Foo</name> <parent-id xsi:type=”integer” xsi:nil=”true”/>
This doesn’t work because the compiler will not insert an implicit conversion on both sides at once, and null requires an implicit conversion to become a nullable type. Instead, you can write task.ActualEndDate = TextBoxActualEndDate.Text != “” ? DateTime.Parse(TextBoxActualEndDate.Text) : new DateTime?(); This only requires one implicit conversion (DateTime to DateTime?). Alternatively, you can cast … Read more
Using the Integer class here is probably what you want to do. The overhead associated with the object is most likely (though not necessarily) trivial to your applications overall responsiveness and performance.
If you just want it to work, then perhaps: using System; using System.ComponentModel; using System.Xml.Serialization; public class Account { // your main property; TODO: your version [XmlIgnore] public Nullable<DateTime> AccountExpirationDate {get;set;} // this is a shim property that we use to provide the serialization [XmlAttribute(“AccountExpirationDate”)] [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)] public DateTime AccountExpirationDateSerialized { get {return AccountExpirationDate.Value;} set … Read more
You can achieve what you want by re-arranging your query a bit. The trick is that the ISNULL has to be on the outside before SQL Server will understand that the resulting value can never be NULL. SELECT ISNULL(CAST( CASE Status WHEN 3 THEN 1 ELSE 0 END AS bit), 0) AS HasStatus FROM dbo.Product … Read more
int? is shorthand for Nullable<int>. This may be the post you were looking for.
Just omit the [Required] attribute from the string somefield property. This will make it create a NULLable column in the db. To make int types allow NULLs in the database, they must be declared as nullable ints in the model: // an int can never be null, so it will be created as NOT NULL … Read more
This would be the null forgiving operator. It tells the compiler “this isn’t null, trust me”, so it does not issue a warning for a possible null reference. In this particular case it tells the compiler that Entity isn’t null.
As Jason says, you can create a variable of the right type and pass that. You might want to encapsulate it in your own method: public static DateTime? TryParse(string text) { DateTime date; if (DateTime.TryParse(text, out date)) { return date; } else { return null; } } … or if you like the conditional operator: … Read more