How to make a number field optional AND have min and max validation?

I am using Sencha Architect 3.1.0 and ExtJS 5.0.

Objective:

I want a number field in the UI to be optional, but if a value is specified, it must be within a certain range.

Background:

It seems as though if I specify a minValue in the number field, it assumes that it's a required field, regardless of "allowBlank: true" or "allowNull: true". Specifying a "minValue" should not automatically make it required. Seems odd.

Also, in Sencha Architect, I don't seem to have an option to specify a Range validation on the model field. How can I add this?

I have a model with an int field as such:

Code:

{
   type: 'int',
   allowNull: true,
   name: 'intField'
}

I have the form field specified as follows:

Code:

                        {
                           xtype: 'numberfield',
                           width: 400,
                           fieldLabel: 'Number must be between 1 and 50 (if specified)',
                           name: 'intField',
                           allowOnlyWhitespace: false,
                           allowDecimals: false,
                           allowExponential: false,
                           maxValue: 50,
                           minValue: 1
                        },

How can I make this work?

Thanks!

How to make a number field optional AND have min and max validation?