Hi Muhammad if i'm right you do'nt need to create a function to get data in your report .

so wath  i think you need to do is to create only a pivot view in xml file and customize it for your research 

Example : 

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

            <field name="name">module.pivot</field>

            <field name="model">Module</field>

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

                <pivot string="NAME YOUR REPORT"> 

                    <field name ="Your Field" type="col"/>

                    <field name="YOUR FIELD" type="row" />

           </pivot>

       </field>

    </record>

And you need also to add pivot in your action 

<field name="view_mode">tree,pivot,graph,form,kanban</field>