Domain of One2Many Child fields on the basis of parent fields.

Today I was working on a module In Odoo11 where I needed to change the domain of a field in the tree view of One2many field on change of the parent field. I searched many things then I found a solution which I am going to explain in this tutorial.  I will try to explain with an example how we going to do so.

 First, let us create the python code.

I am creating two models “parent.model” in which I am adding two fields. One field is M2O and the other is O2M. The other model is “child.model” in which I have added some fields. Let us see how we can change the domain of one of the fields in the child model(product_id) on the basis of parent module field(template_id). In this example, I haved added only those variants in the domain whose sale price is greater than 100. See the code below.

class ParentModel(models.Model):
	_name = 'parent.model'

       template_id = fields.Many2one('product.template',string='Template')
       product_ids = fields.One2many(comodel_name = 'child.model', inverse_name = 'parent_id', string = 'Children Ids')

class ChildModel(models.Model):
     _inherit = 'child.model'

     parent_id = fields.Many2one(comodel_name='parent.model', string="Parent")
     product_id = fields.Many2one(comodel_name='product.product', string="Product")
     lst_price = fields.Float("Sale Price")

     @api.onchange('product_id')
     def onchange_product_id(self):
        variant_ids_list = []
        if self._context.get('template_id'):   //  We will pass this context from the xml view.
            template_id = self.env["product.template"].browse(self._context.get('template_id'))
            for variant_id in template_id.product_variant_ids:
                if variant_id.lst_price >  100:
                     variant_ids_list.append(variant_id.id)
        return result['domain'] = {'product_id': [('id','in',variant_ids_list)]

 Now let us create the XML part.

 <record id="parent_model_id" model="ir.ui.view">
     <field name="name">parent.modle.form</field>
     <field name="model">parnet.model</field>
     <field name="arch" type="xml">
        <form string="Parent Model" version="7.0">
          <sheet>
             <field name="template_id" />
             <field name="product_ids"  context="{'template_id':parent.template_id}"> # Pass the as context the field_name of the parent class using parent.field_name.
                <tree editable="bottom" >
                     <field name="product_id" options="{'no_create_edit':True}"/>
                     <field name="lst_price"/>
                 </tree>
              </field>                   
           </sheet>
         </form>
     </field>            
 </record>

That is it.!!!
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