Relational fields: Many2one, One2many and Many2many

Declaring relations, ondelete, domains, commands for writing x2many values, and relation tables.

In this lesson

The three relational fields
Domains, context and company checks
Commands for x2many values

Key points

Many2one with ondelete set null/restrict/cascade
One2many needs an inverse Many2one
Many2many uses a relation table; name it when needed
Command.create/update/delete/unlink/link/clear/set ↔ tuples 0–6

Real-world example

A script used Command.delete instead of Command.unlink to remove tags from contacts and deleted the tags themselves from the database. Restoring from the morning backup on a copy and re-running with unlink taught the team the difference permanently.

Questions and answers

What's the tuple equivalent of Command.set([1,2])?

(6, 0, [1, 2])

Why name a Many2many relation table explicitly?

When two Many2many fields link the same two models, or for clarity across modules.

Read the full lesson, worked example and quiz