How Do You Map Unsigned Long (ulong) Types in Entity Framework?

Mapping Unsigned Integer and Long Types in Entity Framework

Entity Framework's out-of-the-box mapping for long data types is sufficient for representing signed long values. However, when dealing with unsigned long (ulong) types, things get a bit more complicated. MySQL's EF provider skips ulong data types by default.

Solution for ulong

In older versions of Entity Framework, unsigned data types were not supported. To work around this limitation for ulong columns, a workaround is to store the value in a supported long data type and cast it to ulong when needed.

To implement this solution:

• Create an internal property __MyVariable mapped to the database and of type long.
• Create a public property MyVariable attributed with [NotMapped], which represents the unsigned long value.
• Implement a getter and setter for MyVariable to perform the necessary casting.

<code class="csharp">// Avoid modifying the following directly.
// Used as a database column only.
public long __MyVariable { get; set; }

// Access/modify this variable instead.
// Tell EF not to map this field to a Db table
[NotMapped]
public ulong MyVariable
{
    get
    {
        unchecked
        {
            return (ulong)__MyVariable;
        }
    }

    set
    {
        unchecked
        {
            __MyVariable = (long)value;
        }
    }
}</code>

Note that the casting operations are marked as unchecked to prevent any potential overflow exceptions.

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