Default [PXDBInt] data field to Null value?

Question

How can I have a numeric field allow and default to a Null / unspecified value?

When I add the control for this field to the screen it always defaults to "0" on new entities...

[PXDBInt]
[PXDefault(TypeCode.DBNull, "", PersistingCheck=PXPersistingCheck.Nothing)]
[PXUIField(DisplayName="Nullable Int")]

Answer 1

There is AllowNull attribute in px:PXNumberEdit control. In this implementation you do not even need to add the PXDefault attribute to your field.

I added MinValue = 1, MaxValue = 999999 in c# code and DisplayFormat="n0" MaxLength="6" in .aspx because of my task, it should work without this.

    <px:PXNumberEdit runat="server" ID="edUsrCapacity" DataField="UsrCapacity"
DisplayFormat="n0" MaxLength="6" AllowNull="True" />


    [PXDBInt(MinValue = 1, MaxValue = 999999)]
    [PXUIField(DisplayName = Messages.FsEquipment.Capacity)]
    public virtual int? UsrCapacity
    {
        get;
        set;
    }

    public abstract class usrCapacity : BqlInt.Field<usrCapacity>
    {
    }

Answer 2

The default value for all fields is null unless you force a value with PXDefault.

If you remove the [PXDefault] attribute it will automatically default to null.

Make sure your value is defined as a int? and not int as well. the "?" denotes it as "nullable"

For example:

    #region CurrentConfigRevision
    public abstract class currentConfigRevision : PX.Data.IBqlField
    {
    }
    protected int? _CurrentConfigRevision;
    [PXDBInt]
    [PXUIField(DisplayName="Current Revision")]
    public virtual int? CurrentConfigRevision
    {
        get
        {
            return this._CurrentConfigRevision;
        }
        set
        {
            this._CurrentConfigRevision = value;
        }
    }
    #endregion

This will always have a null value unless the user specifies in the interface (or it's set via code)

Answer 3

The issue here appears to be whether the field is in a Form area or Grid table. In a Grid a null-value is rendered as an empty cell and persists as null if left empty. However, when in a Form area a null value is rendered with "0". If the value is changed attempting to then change it back to empty/null results in a zero value persisting to the database.

The solution I found was when creating the control instead of using a PXNumberEdit type field, changing it to a PXTextEdit field and setting the TextMode property to "Number" gave the desired effect. Null values would render as empty and are distinguished from actual zero values.