[FIX] website_slides: immediately add content to new course

- Create a new course;
- Add content line;
- save.

Before this commit, Odoo raises an invalid field error on 'Course' which
is empty. If you try to select the newly created course, it is missing
in the list.

Now, the course is removed from the view when creating a new content
from a course. But it stays if the content is created directly from the
content menu.

opw-2210360

closes odoo/odoo#48534

X-original-commit: f0b61634
Signed-off-by: Jorge Pinna Puissant (jpp) <jpp@odoo.com>

addons/website_slides/views/slide_channel_views.xml

@@ -61,7 +61,7 @@
                         </div>
                         <notebook colspan="4">
                             <page name="content" string="Content">
-                                <field name="slide_ids" colspan="4" nolabel="1" widget="slide_category_one2many" mode="tree,kanban" context="{'default_channel_id': active_id}">
+                                <field name="slide_ids" colspan="4" nolabel="1" widget="slide_category_one2many" mode="tree,kanban" context="{'default_channel_id': active_id, 'form_view_ref' : 'website_slides.view_slide_slide_form_wo_channel_id'}">
                                      <tree decoration-bf="is_category" editable="bottom">
                                         <field name="sequence" widget="handle"/>
                                         <field name="name"/>

addons/website_slides/views/slide_slide_views.xml

@@ -151,6 +151,18 @@
             </field>
         </record>
 
+        <record id="view_slide_slide_form_wo_channel_id" model="ir.ui.view">
+            <field name="name">slide.slide.form.wo.channel_id</field>
+            <field name="model">slide.slide</field>
+            <field name="inherit_id" ref="view_slide_slide_form"/>
+            <field name="priority" eval="50"/>
+            <field name="mode">primary</field>
+            <field name="type">form</field>
+            <field name="arch" type="xml">
+                <field name="channel_id" position="replace"/>
+            </field>
+        </record>
+
         <record id="slide_slide_view_kanban" model="ir.ui.view">
             <field name="name">slide.slide.view.kanban</field>
             <field name="model">slide.slide</field>