Related Fields and Reference Fields

In many real-world business applications, it's common to need data from one model to be visible in another — without duplicating it. Odoo provides a clean and powerful way to achieve this using related fields and reference fields.

Related Fields

Related fields allow you to fetch and display a value from a field in a related model, typically linked by a Many2one relationship. This is useful when you want to show, for example, the partner's name or email directly in your custom model without re-entering that information.

Basic Usage Example:

partner_id = fields.Many2one('res.partner', string='Partner')
partner_name = fields.Char(string='Partner Name', related='partner_id.name')

By default, related fields are:

• Read-only: The field cannot be modified by the user.
• Not stored in the database: The field value is computed dynamically and not saved in the database.
• Not copied when duplicating a record: The field value will not be carried over when the record is duplicated.

To store the related field in the database — which improves performance for sorting and searching — you can use the store=True attribute:

partner_id = fields.Many2one('res.partner', string='Partner')
partner_name = fields.Char(string='Partner Name', related='partner_id.name', store=True)

This is especially helpful when you’re frequently filtering or grouping based on the related field in views.

Reference Fields

Reference fields in Odoo let you dynamically select a record from multiple models within a single field. Unlike standard relationships (Many2one, One2many), which point to a fixed model, reference fields provide flexibility by letting the user choose the model and then record from that model.

reference = fields.Reference(
    selection=[
        ('sale.order', 'Sale Order'),
        ('purchase.order', 'Purchase Order')
    ],
    string="Reference Document"
)

In this example, the field allows users to link either a Sale Order or Purchase Order.

Dynamic Model Selection from a Method:

reference = fields.Reference(
    selection='get_model_options',
    string="Reference"
)

@api.model
def get_model_options(self):
    models = self.env['ir.model'].search([])
    return [(model.model, model.name) for model in models]

This way, the field dynamically populates the list of available models using a function. Just remember: the returned value must be a list of tuples, where each tuple is (model_name, display_label).