Hide string name from field in odoo 12 - widget

Question

When you define a field in odoo, by default, it displays the string for that value and next to it, the value.
If you don't put the field between group tags, the string value, doesn't appear.
The problem is that I am defining a tree view which doesn't contain group tags:
<record model="ir.ui.view" id="field_partida_fertilizer_tree">
<field name="name">field.diary.partida.fertilizer.tree.view</field>
<field name="model">field.diary.partida.fertilizer</field>
<field name="priority" eval="17"/>
<field name="arch" type="xml">
<tree string="Fertilizante">
<field string= 'Nombre' name="fertilizer"/>
<field string='N' name="nitrato" options='{"show_string": False}' widget="percentpie"/>
<field string='P' name="fosforo" options='{"fg_color": "white"}' widget="percentpie"/>
<field string='K' name="potasio" options='{"fg_color": "white"}' widget="percentpie"/>
<field string='Cantidad (kg)' name="quantity"/>
</tree>
</field>
</record>
By using widget percentpie, I can display this:
I want to hide the letter N next to the graph but not the column and I can't find any property of the widget to do that. The only way I could trick this is by giving the color white to the text so it disappears with the background, but the column cant be centered.
I have tried with the option show_string I found on GitHub but it doesn't work.
Any help would be awesome...
Thank you!

Answer 1

Odoo defines a condition in the PercentPie template to show the string attribute vaue:
<span t-if="widget.string"><t t-esc="widget.string"/></span>
You can alter the template and define a new condition base on a value (show_string ) passed through the options attribute:
<?xml version="1.0" encoding="UTF-8"?>
<templates id="template" xml:space="preserve">
<t t-extend="FieldPercentPie">
<t t-jquery="span" t-operation="attributes">
<attribute name="t-if">widget.string and (widget.attrs.options.show_string === undefined or widget.attrs.options.show_string)</attribute>
</t>
</t>
</templates>
Create a new XML file with the above content and add it under the qweb section of the manifest file.
Example:
<record model="ir.ui.view" id="field_partida_fertilizer_tree">
<field name="name">field.diary.partida.fertilizer.tree.view</field>
<field name="model">field.diary.partida.fertilizer</field>
<field name="priority" eval="17"/>
<field name="arch" type="xml">
<tree string="Fertilizante">
<field string='Nombre' name="fertilizer"/>
<field name="nitrato" options='{"show_string": False}' widget="percentpie"/>
<field name="fosforo" options='{"show_string": False}' widget="percentpie"/>
<field name="potasio" options='{"show_string": False}' widget="percentpie"/>
<field string='Cantidad (kg)' name="quantity"/>
</tree>
</field>