Hi Odoo developers,

I would want to show a many2many field from a module in its tree view but splitted in columns. Here is my example.

I have a TodoTask model with a field named tag_ids (a task may have multiple tags).

class TodoTask(models.Model):
    _inherit = 'todo.task'
    # Relational fields
    stage_id = fields.Many2one('todo.task.stage', 'Stage')
    tag_ids = fields.Many2many(
        'todo.task.tag',      # related= (model name)
        'todo_task_tag_rel',  # relation= (table name)
        'task_id',               # column1= ("this" field)
        'tag_id',                # column2= ("other" field)
        string='Tags',
        # Relational field attributes:
        auto_join=False,
        context="{}",
        domain="[]",
        ondelete='cascade',
    )

The Tag model:

class Tag(models.Model):
    _name = 'todo.task.tag'
    name = fields.Char('Name', size=40, translate=True)
    # Many2many inverse relation
    task_ids = fields.Many2many('todo.task', string='Tasks')
    # Hierarchic relations:
    _parent_store = True
    _parent_name = 'parent_id'  # the default
    parent_id = fields.Many2one(
        'todo.task.tag', 'Parent Tag', ondelete='restrict')
    parent_left = fields.Integer('Parent Left', index=True)
    parent_right = fields.Integer('Parent Right', index=True)
    child_ids = fields.One2many('todo.task.tag', 'parent_id', 'Child Tags')

The tree view associated to TodoTask model:

<record id="todo_app.view_tree_todo_task" model="ir.ui.view">
      <field name="name">To-do Task Tree</field>
      <field name="model">todo.task</field>
      <field name="arch" type="xml">
        <tree colors="gray:is_done==True"
              font="italic:stage_state!='open'"
              delete="false">
          <field name="is_done" invisible="True"/>
          <field name="stage_state" invisible="True"/>
          <field name="name"/>
          <field name="tag_ids"/>
        </tree>
      </field>
    </record>

The most important part of the above view is field name="tag_ids".
tag_ids is a Many2Many field in TodoTask model (todo.task) related to Tag model (todo.task.tag).

The problem is that this tree view shows only one column for tag_ids (see column Tags in the next image).

 http://i.imgur.com/G44hQh4.png

I would like to show the Many2Many field (tag_ids) from TodoTask model in more than one column in the tree view associated to TodoTask model: one column for tag name, another column for another field from Tag model, ...

nameCourse | start_date Course | tag name | tag parent name |
------------------------------------------------------------------------------------
course 1         2015-5-15                 tag1          tag2
course 1         2015-5-15                 tag3          tag2