Hello, I found the solution.

<record model="ir.ui.view" id="oms_res_partner_customer_required_form">

<field name="name">oms.res.partner.customer.required.form</field>

<field name="model">res.partner</field>

<field name="inherit_id" ref="base.view_partner_form" />

<field name="arch" type="xml">

<xpath

expr="//field[@name='user_id']"

position = "replace">

<field name="user_id" attrs="{'required': ['|',('customer','=', 1),('customer','=', True)]}"/>

</xpath>

</field>

</record>

I had to add the condition customer = 1 when I'm creating the partner, and customer = true when I'm editing it.

Hi victor,

    I have done same thing by putting attrs in existing field(user_id).

<record id="res_partner_form_inherit" model="ir.ui.view">

<field name="name">res.partner.form.inherit</field>

<field name="model">res.partner</field>

<field name="inherit_id" ref="base.view_partner_form" />

<field name="arch" type="xml">

<field name='user_id' position='attributes'>

<attribute name='attrs'>{'required':[('customer','=',True)]}</attribute>

</field>

.............

</field>

</record>

Hope this will help u little bit....

he reason it only works for editing existing customer lays in default values.When you create new record it doess not know if it is customer or supplier.. (both values are false by default)Only when you save the record the system knows the walue of the field....

would try setting default ( add customer=True to context of action opening partners from purchases menu) and define default for vaule customer on res.partner model... that way when you create partner from purchases ( supplier will be marked Ture) and you will have desired behaivour... that is just an ugly workarround but could do the trick....

hope it helps