Question

Can anyone explain the following behaviour to me?

When a field type in an AX Table is set to an Enum, you can select any of the Enum values as a value for the field.

But if you make the field Mandatory, you can no longer select the first Enum value in the list through the user interface.

Obviously this can be worked around by not making the field Mandatory. I am looking for an explanation of this bizarre behaviour.

Answer 1

AX does not have a null value concept. Instead the following values are considered “not entered” by defintion:

• string: blank
• int and int64: 0 (zero)
• enum: 0 (typically the first value)
• date: 01\01\1900 (displays as blank)

For new base enums make a blank zero enum value (by convention name it None). This will make the use of mandatory fields possible for this enum type.

Also have a look on this: Mark mandatory fields on form, if not filled with valid value