odoo-model-relations

name	Odoo Model Relations
description	Define Many2one, One2many, and Many2many fields to relate models.

Odoo Model Relations

Goal

Link the estate.property model to other models like Property Type, Buyer, Seller, Offers, and Tags.

1. Many2one (fields.Many2one)

Links a record to a single record in another model (Parent/Foreign Key).

• Database side: Adds a column field_id (integer) to the table.
• Convention: Field name should end with _id (e.g., partner_id).

Example:

# In estate.property model
property_type_id = fields.Many2one("estate.property.type", string="Property Type")
buyer_id = fields.Many2one("res.partner", string="Buyer")
seller_id = fields.Many2one("res.partner", string="Seller", default=lambda self: self.env.user)

2. Many2many (fields.Many2many)

Bidirectional multiple relationship. A record can be related to multiple records in another model.

• Database side: Creates a hidden relational table (e.g., estate_property_tag_rel).
• Convention: Field name should end with _ids (e.g., tag_ids).

Example:

# In estate.property model
tag_ids = fields.Many2many("estate.property.tag", string="Tags")

• Widget: Use widget="many2many_tags" in the view to display as chips.

3. One2many (fields.One2many)

The inverse of a Many2one. Displays a list of records from the related model that point to the current record.

• Database side: No column in the current table. It relies on the Many2one field in the co-model.
• Requirement: The co-model MUST have a Many2one field pointing back to this model.
• Convention: Field name should end with _ids (e.g., offer_ids).

Example:

# In estate.property model
offer_ids = fields.One2many("estate.property.offer", "property_id", string="Offers")

# In estate.property.offer model (The Co-model)
property_id = fields.Many2one("estate.property", required=True)

4. The self.env Environment

• self.env: Access to the environment.
• self.env.user: Current logged-in user record.
• self.env.ref('xml_id'): Get a record by its XML ID.
• self.env['model.name']: Access a model registry to search/create records.

5. UI Tips

• Notebooks/Pages: Use <notebook> and <page> in Form views to organize relational fields (like lists of offers).
• Inline Views: You can define the view of a One2many field inline inside the Form view if it differs from the default list view.