[IMP] uom: measurement type on category

In order to restrict some uom field to some uom category, it is required to
add a measurement type on uom.category. Also, this will lessen the use of
master data.

Some technical justifications:
- measure_type is not required, to allow people creating their own
uom.category. Those ones will not interfere with addons business.
- measure_type is unique: we restrict to only one category containing
time, weight, ... in order to avoid mismatch category during conversion.
(2 different weight categories can not be converted).
- measure_type on uom.uom is stored: to allow search and domain on
field, we need to store it. Usually, UoM are not updated every day,
and the number of uom in a database is not that important.

To illustrate this mecanism, a domain is added on
'project_time_mode_id', in project module. This field
is use as timesheet default uom, and we obviously want to
restrict it to time category (timesheeting in liter does
not make sense ...)

Task #1820076

3 files changed, 18 insertions, 0 deletions

diff --git a/addons/uom/data/uom_data.xml b/addons/uom/data/uom_data.xml
index f929564b1e4..59a2c41208c 100644
--- a/addons/uom/data/uom_data.xml
+++ b/addons/uom/data/uom_data.xml
@@ -6,18 +6,23 @@
         -->
         <record id="product_uom_categ_unit" model="uom.category">
             <field name="name">Unit</field>
+            <field name="measure_type">unit</field>
         </record>
         <record id="product_uom_categ_kgm" model="uom.category">
             <field name="name">Weight</field>
+            <field name="measure_type">weight</field>
         </record>
         <record id="uom_categ_wtime" model="uom.category">
             <field name="name">Working Time</field>
+            <field name="measure_type">time</field>
         </record>
         <record id="uom_categ_length" model="uom.category">
             <field name="name">Length / Distance</field>
+            <field name="measure_type">length</field>
         </record>
         <record id="product_uom_categ_vol" model="uom.category">
             <field name="name">Volume</field>
+            <field name="measure_type">volume</field>
         </record>
        <!--
             Resource: uom.uom
diff --git a/addons/uom/models/uom_uom.py b/addons/uom/models/uom_uom.py
index 2c01624b5c6..9608894e485 100644
--- a/addons/uom/models/uom_uom.py
+++ b/addons/uom/models/uom_uom.py
@@ -10,6 +10,17 @@ class UoMCategory(models.Model):
     _description = 'Product UoM Categories'
 
     name = fields.Char('Name', required=True, translate=True)
+    measure_type = fields.Selection([
+        ('unit', 'Units'),
+        ('weight', 'Weight'),
+        ('time', 'Time'),
+        ('length', 'Length'),
+        ('volume', 'Volume'),
+    ], string="Type of Measure")
+
+    _sql_constraints = [
+        ('uom_category_unique_type', 'UNIQUE(measure_type)', 'You can have only one category per measurement type.'),
+    ]
 
 
 class UoM(models.Model):
@@ -38,6 +49,7 @@ class UoM(models.Model):
         ('reference', 'Reference Unit of Measure for this category'),
         ('smaller', 'Smaller than the reference Unit of Measure')], 'Type',
         default='reference', required=1)
+    measure_type = fields.Selection(string="Type of measurement category", related='category_id.measure_type', store=True, readonly=True)
 
     _sql_constraints = [
         ('factor_gt_zero', 'CHECK (factor!=0)', 'The conversion ratio for a unit of measure cannot be 0!'),
diff --git a/addons/uom/views/uom_uom_views.xml b/addons/uom/views/uom_uom_views.xml
index 582ae8174c2..59acc96e86f 100644
--- a/addons/uom/views/uom_uom_views.xml
+++ b/addons/uom/views/uom_uom_views.xml
@@ -68,6 +68,7 @@
             <form string="Units of Measure categories">
                 <group>
                     <field name="name"/>
+                    <field name="measure_type"/>
                 </group>
             </form>
         </field>