Convert M2O fields to M2M

Add explainations to the user about the algo
Update translation files

purchase_suggest/wizard/purchase_suggest.py

@@ -33,10 +33,10 @@ class PurchaseSuggestionGenerate(models.TransientModel):
     _name = 'purchase.suggest.generate'
     _description = 'Start to generate the purchase suggestions'
 
-    categ_id = fields.Many2one(
-        'product.category', string='Product Category')
-    seller_id = fields.Many2one(
-        'res.partner', string='Supplier',
+    categ_ids = fields.Many2many(
+        'product.category', string='Product Categories')
+    seller_ids = fields.Many2many(
+        'res.partner', string='Suppliers',
         domain=[('supplier', '=', True), ('is_company', '=', True)])
     location_id = fields.Many2one(
         'stock.location', string='Stock Location', required=True,
@@ -77,14 +77,14 @@ class PurchaseSuggestionGenerate(models.TransientModel):
             ('company_id', '=', self.env.user.company_id.id),
             ('location_id', 'child_of', self.location_id.id),
             ]
-        if self.categ_id or self.seller_id:
+        if self.categ_ids or self.seller_ids:
             product_domain = []
-            if self.categ_id:
+            if self.categ_ids:
                 product_domain.append(
-                    ('categ_id', 'child_of', self.categ_id.id))
-            if self.seller_id:
+                    ('categ_id', 'in', self.categ_ids.ids))
+            if self.seller_ids:
                 product_domain.append(
-                    ('seller_id', '=', self.seller_id.id))
+                    ('seller_id', 'in', self.seller_ids.ids))
             products_subset = ppo.search(product_domain)
             op_domain.append(('product_id', 'in', products_subset.ids))
         ops = swoo.search(op_domain)
@@ -160,8 +160,7 @@ class PurchaseSuggestionGenerate(models.TransientModel):
             return action
         else:
             raise Warning(_(
-                "The virtual stock for all related products is above the "
-                "minimum stock level."))
+                "There are no purchase suggestions to generate."))
 
 
 class PurchaseSuggest(models.TransientModel):
@@ -172,7 +171,8 @@ class PurchaseSuggest(models.TransientModel):
     product_id = fields.Many2one(
         'product.product', string='Product', required=True, readonly=True)
     seller_id = fields.Many2one(
-        'res.partner', string='Supplier', readonly=True)
+        'res.partner', string='Supplier', readonly=True,
+        domain=[('supplier', '=', True)])
     qty_available = fields.Float(
         string='Quantity On Hand', readonly=True,
         digits=dp.get_precision('Product Unit of Measure'))

purchase_suggest/wizard/purchase_suggest_view.xml

@@ -14,9 +14,18 @@
     <field name="model">purchase.suggest.generate</field>
     <field name="arch" type="xml">
         <form string="Generate Purchase Suggestions">
+            <p>This wizard will generate purchase suggestions based on the following rules:</p>
+            <ol>
+                <li>it will search all the re-ordering rules linked to the selected stock location, limited to the product categories and the suppliers if some were selected</li>
+                <li>if the quantity on hand + incoming quantity - outgoing quantity + quantity in draft purchase orders is strictly inferior to the minimum stock level, it will create a purchase suggestion line</li>
+            </ol>
+
+            <p>The purchase suggestion lines display as much information as possible to help you take the decision on the quantity that you would like to re-order. When you have decided the quantity you want to re-order, enter that value in the last column.</p>
+
+            <p>Once you have entered a Quantity to Order for all the lines you would like to re-order, select all the lines and click on <i>More</i> > <i>Create Purchase Orders</i>.</p>
             <group name="name">
-                <field name="categ_id"/>
-                <field name="seller_id"/>
+                <field name="categ_ids" widget="many2many_tags"/>
+                <field name="seller_ids" widget="many2many_tags"/>
                 <field name="location_id"/>
             </group>
             <footer>
@@ -86,7 +95,7 @@
     <field name="arch"  type="xml">
         <form string="Create Purchase Orders">
             <p class="oe_grey">
-                This wizard will create Purchase Orders.
+                Click on the red button below to create the purchase orders.
             </p>
             <footer>
                 <button type="object" name="create_po"