I'm working with models project.task that is related with account.analytic.line(task_id = fields.M2o('project.task')) and project.task.material(task_id = fields.M2o('project.task')) that is also related to project.task.

I now want to connect models account.analytic.line and project.task.material. So I added a field to account.analytic.line (material_id = fields.M2o('project.task.material'))

Now I extended the timesheets(account.analytic.line) view that is a tree view in a form view with the material_id.

<record id="account_analytic_line_task_extension_form_view" model="ir.ui.view">
    <field name="inherit_id" ref="hr_timesheet.view_task_form2_inherited" />
    <field name="model">project.task</field>
    <field name="arch" type="xml">
        <xpath expr="//field[@name='unit_amount']" position="after">
            <field name="material_id" domain="[('task_id', '=', id)]"/>
        </xpath>
     </field>
</record>

I want to show only the materials that are connected to the task, but none are shown?! How to create the filter so it will show the materials that are added to the task?

Modules user are project, hr_timesheet and custom app \https://www.odoo.com/apps/modules/10.0/project_task_material/