.. _reference/orm: ======= ORM API ======= .. automodule:: odoo.models .. _reference/orm/models: .. _reference/orm/model: Models ====== Model fields are defined as attributes on the model itself:: from odoo import models, fields class AModel(models.Model): _name = 'a.model.name' field1 = fields.Char() .. warning:: this means you cannot define a field and a method with the same name, the last one will silently overwrite the former ones. By default, the field's label (user-visible name) is a capitalized version of the field name, this can be overridden with the ``string`` parameter. :: field2 = fields.Integer(string="Field Label") For the list of field types and parameters, see :ref:`the fields reference `. Default values are defined as parameters on fields, either as a value:: name = fields.Char(default="a value") or as a function called to compute the default value, which should return that value:: def _default_name(self): return self.get_value() name = fields.Char(default=lambda self: self._default_name()) .. rubric:: API .. autoclass:: odoo.models.BaseModel() .. autoattribute:: _auto .. autoattribute:: _table .. autoattribute:: _sequence .. autoattribute:: _sql_constraints .. autoattribute:: _register .. autoattribute:: _name .. autoattribute:: _description .. autoattribute:: _inherit .. autoattribute:: _inherits .. autoattribute:: _rec_name .. autoattribute:: _order .. autoattribute:: _check_company_auto .. autoattribute:: _parent_name .. autoattribute:: _parent_store .. autoattribute:: _abstract .. seealso:: :class:`odoo.models.AbstractModel` .. autoattribute:: _transient .. seealso:: :class:`odoo.models.TransientModel` .. autoattribute:: _date_name .. autoattribute:: _fold_name AbstractModel ------------- .. autoclass:: odoo.models.AbstractModel() Model ----- .. autoclass:: odoo.models.Model() TransientModel -------------- .. autoclass:: odoo.models.TransientModel() .. _reference/fields: .. _reference/orm/fields: Fields ====== .. currentmodule:: odoo.fields .. autoclass:: Field() .. .. autoattribute:: Field._slots :annotation: .. _reference/fields/basic: Basic Fields ------------ .. autoclass:: Boolean() .. autoclass:: Char() .. autoclass:: Float() .. autoclass:: Integer() .. _reference/fields/advanced: Advanced Fields --------------- .. autoclass:: Binary() .. autoclass:: Html() .. autoclass:: Image() .. autoclass:: Monetary() .. autoclass:: Selection() .. autoclass:: Text() .. _reference/fields/date: Date(time) Fields ''''''''''''''''' :class:`Dates ` and :class:`Datetimes ` are very important fields in any kind of business application. Their misuse can create invisible yet painful bugs, this section aims to provide Odoo developers with the knowledge required to avoid misusing these fields. When assigning a value to a Date/Datetime field, the following options are valid: * A `date` or `datetime` object. * A string in the proper server format: * ``YYYY-MM-DD`` for :class:`~odoo.fields.Date` fields, * ``YYYY-MM-DD HH:MM:SS`` for :class:`~odoo.fields.Datetime` fields. * `False` or `None`. The Date and Datetime fields class have helper methods to attempt conversion into a compatible type: * :func:`~odoo.fields.Date.to_date` will convert to a :class:`datetime.date` * :func:`~odoo.fields.Datetime.to_datetime` will convert to a :class:`datetime.datetime`. .. admonition:: Example To parse date/datetimes coming from external sources:: fields.Date.to_date(self._context.get('date_from')) Date / Datetime comparison best practices: * Date fields can **only** be compared to date objects. * Datetime fields can **only** be compared to datetime objects. .. warning:: Strings representing dates and datetimes can be compared between each other, however the result may not be the expected result, as a datetime string will always be greater than a date string, therefore this practice is **heavily** discouraged. Common operations with dates and datetimes such as addition, subtraction or fetching the start/end of a period are exposed through both :class:`~odoo.fields.Date` and :class:`~odoo.fields.Datetime`. These helpers are also available by importing `odoo.tools.date_utils`. .. note:: Timezones Datetime fields are stored as `timestamp without timezone` columns in the database and are stored in the UTC timezone. This is by design, as it makes the Odoo database independent from the timezone of the hosting server system. Timezone conversion is managed entirely by the client side. .. autoclass:: Date() :members: today, context_today, to_date, to_string, start_of, end_of, add, subtract .. autoclass:: Datetime() :members: now, today, context_timestamp, to_datetime, to_string, start_of, end_of, add, subtract .. _reference/fields/relational: Relational Fields ''''''''''''''''' .. autoclass:: Many2one() .. autoclass:: One2many() .. autoclass:: Many2many() Pseudo-relational fields '''''''''''''''''''''''' .. autoclass:: Reference() .. autoclass:: Many2oneReference() .. _reference/fields/compute: Computed Fields ''''''''''''''' Fields can be computed (instead of read straight from the database) using the ``compute`` parameter. **It must assign the computed value to the field**. If it uses the values of other *fields*, it should specify those fields using :func:`~odoo.api.depends`. :: from odoo import api total = fields.Float(compute='_compute_total') @api.depends('value', 'tax') def _compute_total(self): for record in self: record.total = record.value + record.value * record.tax * dependencies can be dotted paths when using sub-fields:: @api.depends('line_ids.value') def _compute_total(self): for record in self: record.total = sum(line.value for line in record.line_ids) * computed fields are not stored by default, they are computed and returned when requested. Setting ``store=True`` will store them in the database and automatically enable searching. * searching on a computed field can also be enabled by setting the ``search`` parameter. The value is a method name returning a :ref:`reference/orm/domains`. :: upper_name = field.Char(compute='_compute_upper', search='_search_upper') def _search_upper(self, operator, value): if operator == 'like': operator = 'ilike' return [('name', operator, value)] The search method is invoked when processing domains before doing an actual search on the model. It must return a domain equivalent to the condition: ``field operator value``. .. TODO and/or by setting the store to True for search domains ? * Computed fields are readonly by default. To allow *setting* values on a computed field, use the ``inverse`` parameter. It is the name of a function reversing the computation and setting the relevant fields:: document = fields.Char(compute='_get_document', inverse='_set_document') def _get_document(self): for record in self: with open(record.get_document_path) as f: record.document = f.read() def _set_document(self): for record in self: if not record.document: continue with open(record.get_document_path()) as f: f.write(record.document) * multiple fields can be computed at the same time by the same method, just use the same method on all fields and set all of them:: discount_value = fields.Float(compute='_apply_discount') total = fields.Float(compute='_apply_discount') @api.depends('value', 'discount') def _apply_discount(self): for record in self: # compute actual discount from discount percentage discount = record.value * record.discount record.discount_value = discount record.total = record.value - discount .. warning:: While it is possible to use the same compute method for multiple fields, it is not recommended to do the same for the inverse method. During the computation of the inverse, **all** fields that use said inverse are protected, meaning that they can't be computed, even if their value is not in the cache. If any of those fields is accessed and its value is not in cache, the ORM will simply return a default value of `False` for these fields. This means that the value of the inverse fields (other than the one triggering the inverse method) may not give their correct value and this will probably break the expected behavior of the inverse method. .. _reference/fields/related: Related fields '''''''''''''' A special case of computed fields are *related* (proxy) fields, which provide the value of a sub-field on the current record. They are defined by setting the ``related`` parameter and like regular computed fields they can be stored:: nickname = fields.Char(related='user_id.partner_id.name', store=True) The value of a related field is given by following a sequence of relational fields and reading a field on the reached model. The complete sequence of fields to traverse is specified by the ``related`` attribute. Some field attributes are automatically copied from the source field if they are not redefined: ``string``, ``help``, ``readonly``, ``required`` (only if all fields in the sequence are required), ``groups``, ``digits``, ``size``, ``translate``, ``sanitize``, ``selection``, ``comodel_name``, ``domain``, ``context``. All semantic-free attributes are copied from the source field. By default, the values of related fields are not stored to the database. Add the attribute ``store=True`` to make it stored, just like computed fields. Related fields are automatically recomputed when their dependencies are modified. .. note:: The related fields are computed in sudo mode. .. warning:: You cannot chain :class:`~odoo.fields.Many2many` or :class:`~odoo.fields.One2many` fields in ``related`` fields dependencies. ``related`` can be used to refer to a :class:`~odoo.fields.One2many` or :class:`~odoo.fields.Many2many` field on another model on the condition that it's done through a ``Many2one`` relation on the current model. ``One2many`` and ``Many2many`` are not supported and the results will not be aggregated correctly:: m2o_id = fields.Many2one() m2m_ids = fields.Many2many() o2m_ids = fields.One2many() # Supported d_ids = fields.Many2many(related="m2o_id.m2m_ids") e_ids = fields.One2many(related="m2o_id.o2m_ids") # Won't work: use a custom Many2many computed field instead f_ids = fields.Many2many(related="m2m_ids.m2m_ids") g_ids = fields.One2many(related="o2m_ids.o2m_ids") .. _reference/fields/automatic: Automatic fields ---------------- .. Documented .. attribute:: id Identifier :class:`field ` If length of current recordset is 1, return id of unique record in it. Raise an Error otherwise. .. todo:: _log_access info .. attribute:: create_date :class:`~odoo.fields.Datetime` .. attribute:: create_uid :class:`~odoo.fields.Many2one` .. attribute:: write_date :class:`~odoo.fields.Datetime` .. attribute:: write_uid :class:`~odoo.fields.Many2one` .. _reference/orm/fields/reserved: Reserved Field names -------------------- A few field names are reserved for pre-defined behaviors beyond that of automated fields. They should be defined on a model when the related behavior is desired: .. attribute:: name default value for :attr:`~odoo.models.BaseModel._rec_name`, used to display records in context where a representative "naming" is necessary. :class:`~odoo.fields.Char` .. attribute:: active toggles the global visibility of the record, if ``active`` is set to ``False`` the record is invisible in most searches and listing. :class:`~odoo.fields.Boolean` .. .. attribute:: sequence .. .. Alterable ordering criteria, allows drag-and-drop reordering of models .. in list views. .. .. :class:`~odoo.fields.Integer` .. attribute:: state lifecycle stages of the object, used by the ``states`` attribute on :class:`fields `. :class:`~odoo.fields.Selection` .. attribute:: parent_id default_value of :attr:`~._parent_name`, used to organize records in a tree structure and enables the ``child_of`` and ``parent_of`` operators in domains. :class:`~odoo.fields.Many2one` .. attribute:: parent_path When :attr:`~._parent_store` is set to True, used to store a value reflecting the tree structure of :attr:`~._parent_name`, and to optimize the operators ``child_of`` and ``parent_of`` in search domains. It must be declared with ``index=True`` for proper operation. :class:`~odoo.fields.Char` .. attribute:: company_id Main field name used for Odoo multi-company behavior. Used by `:meth:~odoo.models._check_company` to check multi company consistency. Defines whether a record is shared between companies (no value) or only accessible by the users of a given company. :class:`~odoo.fields.Many2one` :type: :class:`~odoo.addons.base.models.res_company` Recordsets ========== Interactions with models and records are performed through recordsets, an ordered collection of records of the same model. .. warning:: Contrary to what the name implies, it is currently possible for recordsets to contain duplicates. This may change in the future. Methods defined on a model are executed on a recordset, and their ``self`` is a recordset:: class AModel(models.Model): _name = 'a.model' def a_method(self): # self can be anything between 0 records and all records in the # database self.do_operation() Iterating on a recordset will yield new sets of *a single record* ("singletons"), much like iterating on a Python string yields strings of a single characters:: def do_operation(self): print(self) # => a.model(1, 2, 3, 4, 5) for record in self: print(record) # => a.model(1), then a.model(2), then a.model(3), ... Field access ------------ Recordsets provide an "Active Record" interface: model fields can be read and written directly from the record as attributes. .. note:: When accessing non-relational fields on a recordset of potentially multiple records, use :meth:`~odoo.models.BaseModel.mapped`:: total_qty = sum(self.mapped('qty')) Field values can also be accessed like dict items, which is more elegant and safer than ``getattr()`` for dynamic field names. Setting a field's value triggers an update to the database:: >>> record.name Example Name >>> record.company_id.name Company Name >>> record.name = "Bob" >>> field = "name" >>> record[field] Bob .. warning:: Trying to read a field on multiple records will raise an error for non relational fields. Accessing a relational field (:class:`~odoo.fields.Many2one`, :class:`~odoo.fields.One2many`, :class:`~odoo.fields.Many2many`) *always* returns a recordset, empty if the field is not set. Record cache and prefetching ---------------------------- Odoo maintains a cache for the fields of the records, so that not every field access issues a database request, which would be terrible for performance. The following example queries the database only for the first statement:: record.name # first access reads value from database record.name # second access gets value from cache To avoid reading one field on one record at a time, Odoo *prefetches* records and fields following some heuristics to get good performance. Once a field must be read on a given record, the ORM actually reads that field on a larger recordset, and stores the returned values in cache for later use. The prefetched recordset is usually the recordset from which the record comes by iteration. Moreover, all simple stored fields (boolean, integer, float, char, text, date, datetime, selection, many2one) are fetched altogether; they correspond to the columns of the model's table, and are fetched efficiently in the same query. Consider the following example, where ``partners`` is a recordset of 1000 records. Without prefetching, the loop would make 2000 queries to the database. With prefetching, only one query is made:: for partner in partners: print partner.name # first pass prefetches 'name' and 'lang' # (and other fields) on all 'partners' print partner.lang The prefetching also works on *secondary records*: when relational fields are read, their values (which are records) are subscribed for future prefetching. Accessing one of those secondary records prefetches all secondary records from the same model. This makes the following example generate only two queries, one for partners and one for countries:: countries = set() for partner in partners: country = partner.country_id # first pass prefetches all partners countries.add(country.name) # first pass prefetches all countries .. _reference/api/decorators: Method decorators ================= .. automodule:: odoo.api :members: depends, depends_context, constrains, onchange, returns, model, model_create_multi .. .. currentmodule:: odoo.api .. .. autodata:: model .. .. autodata:: depends .. .. autodata:: constrains .. .. autodata:: onchange .. .. autodata:: returns .. todo:: With sphinx 2.0 : autodecorator .. todo:: Add in Views reference * It is possible to suppress the trigger from a specific field by adding ``on_change="0"`` in a view:: will not trigger any interface update when the field is edited by the user, even if there are function fields or explicit onchange depending on that field. .. _reference/orm/environment: Environment =========== The :class:`~odoo.api.Environment` stores various contextual data used by the ORM: the database cursor (for database queries), the current user (for access rights checking) and the current context (storing arbitrary metadata). The environment also stores caches. All recordsets have an environment, which is immutable, can be accessed using :attr:`~odoo.models.Model.env` and gives access to: * the current user (:attr:`~odoo.api.Environment.user`) * the cursor (:attr:`~odoo.api.Environment.cr`) * the superuser flag (:attr:`~odoo.api.Environment.su`) * or the context (:attr:`~odoo.api.Environment.context`) .. code-block:: bash >>> records.env >>> records.env.user res.user(3) >>> records.env.cr >> self.env['res.partner'] res.partner() >>> self.env['res.partner'].search([['is_company', '=', True], ['customer', '=', True]]) res.partner(7, 18, 12, 14, 17, 19, 8, 31, 26, 16, 13, 20, 30, 22, 29, 15, 23, 28, 74) .. currentmodule:: odoo.api .. automethod:: Environment.ref .. autoattribute:: Environment.lang .. autoattribute:: Environment.user .. autoattribute:: Environment.company .. autoattribute:: Environment.companies .. TODO cr, uid but not @property or methods of Environment class... Altering the environment ------------------------ .. currentmodule:: odoo.models .. automethod:: Model.with_context .. automethod:: Model.with_user .. automethod:: Model.with_env .. automethod:: Model.sudo .. _reference/orm/sql: SQL Execution ------------- The :attr:`~odoo.api.Environment.cr` attribute on environments is the cursor for the current database transaction and allows executing SQL directly, either for queries which are difficult to express using the ORM (e.g. complex joins) or for performance reasons:: self.env.cr.execute("some_sql", params) Because models use the same cursor and the :class:`~odoo.api.Environment` holds various caches, these caches must be invalidated when *altering* the database in raw SQL, or further uses of models may become incoherent. It is necessary to clear caches when using ``CREATE``, ``UPDATE`` or ``DELETE`` in SQL, but not ``SELECT`` (which simply reads the database). .. note:: Clearing caches can be performed using the :meth:`~odoo.models.Model.invalidate_cache` method. .. automethod:: Model.invalidate_cache .. warning:: Executing raw SQL bypasses the ORM, and by consequent, Odoo security rules. Please make sure your queries are sanitized when using user input and prefer using ORM utilities if you don't really need to use SQL queries. .. _reference/orm/models/crud: Common ORM methods ================== .. currentmodule:: odoo.models Create/update ------------- .. todo:: api.model_create_multi information .. automethod:: Model.create .. automethod:: Model.copy .. automethod:: Model.default_get .. automethod:: Model.name_create .. automethod:: Model.write .. automethod:: Model.flush Search/Read ----------- .. automethod:: Model.browse .. automethod:: Model.search .. automethod:: Model.search_count .. automethod:: Model.name_search .. automethod:: Model.read .. automethod:: Model.read_group Fields/Views '''''''''''' .. automethod:: Model.fields_get .. automethod:: Model.fields_view_get .. _reference/orm/domains: Search domains '''''''''''''' A domain is a list of criteria, each criterion being a triple (either a ``list`` or a ``tuple``) of ``(field_name, operator, value)`` where: * ``field_name`` (``str``) a field name of the current model, or a relationship traversal through a :class:`~odoo.fields.Many2one` using dot-notation e.g. ``'street'`` or ``'partner_id.country'`` * ``operator`` (``str``) an operator used to compare the ``field_name`` with the ``value``. Valid operators are: ``=`` equals to ``!=`` not equals to ``>`` greater than ``>=`` greater than or equal to ``<`` less than ``<=`` less than or equal to ``=?`` unset or equals to (returns true if ``value`` is either ``None`` or ``False``, otherwise behaves like ``=``) ``=like`` matches ``field_name`` against the ``value`` pattern. An underscore ``_`` in the pattern stands for (matches) any single character; a percent sign ``%`` matches any string of zero or more characters. ``like`` matches ``field_name`` against the ``%value%`` pattern. Similar to ``=like`` but wraps ``value`` with '%' before matching ``not like`` doesn't match against the ``%value%`` pattern ``ilike`` case insensitive ``like`` ``not ilike`` case insensitive ``not like`` ``=ilike`` case insensitive ``=like`` ``in`` is equal to any of the items from ``value``, ``value`` should be a list of items ``not in`` is unequal to all of the items from ``value`` ``child_of`` is a child (descendant) of a ``value`` record (value can be either one item or a list of items). Takes the semantics of the model into account (i.e following the relationship field named by :attr:`~odoo.models.Model._parent_name`). ``parent_of`` is a parent (ascendant) of a ``value`` record (value can be either one item or a list of items). Takes the semantics of the model into account (i.e following the relationship field named by :attr:`~odoo.models.Model._parent_name`). * ``value`` variable type, must be comparable (through ``operator``) to the named field. Domain criteria can be combined using logical operators in *prefix* form: ``'&'`` logical *AND*, default operation to combine criteria following one another. Arity 2 (uses the next 2 criteria or combinations). ``'|'`` logical *OR*, arity 2. ``'!'`` logical *NOT*, arity 1. .. note:: Mostly to negate combinations of criteria Individual criterion generally have a negative form (e.g. ``=`` -> ``!=``, ``<`` -> ``>=``) which is simpler than negating the positive. .. admonition:: Example To search for partners named *ABC*, from belgium or germany, whose language is not english:: [('name','=','ABC'), ('language.code','!=','en_US'), '|',('country_id.code','=','be'), ('country_id.code','=','de')] This domain is interpreted as: .. code-block:: text (name is 'ABC') AND (language is NOT english) AND (country is Belgium OR Germany) Unlink ------ .. automethod:: Model.unlink .. _reference/orm/records/info: Record(set) information ----------------------- .. autoattribute:: Model.ids .. attribute:: env Returns the environment of the given recordset. :type: :class:`~odoo.api.Environment` .. todo:: Environment documentation .. automethod:: Model.exists .. automethod:: Model.ensure_one .. automethod:: Model.name_get .. automethod:: Model.get_metadata .. _reference/orm/records/operations: Operations ---------- Recordsets are immutable, but sets of the same model can be combined using various set operations, returning new recordsets. .. addition preserves order but can introduce duplicates * ``record in set`` returns whether ``record`` (which must be a 1-element recordset) is present in ``set``. ``record not in set`` is the inverse operation * ``set1 <= set2`` and ``set1 < set2`` return whether ``set1`` is a subset of ``set2`` (resp. strict) * ``set1 >= set2`` and ``set1 > set2`` return whether ``set1`` is a superset of ``set2`` (resp. strict) * ``set1 | set2`` returns the union of the two recordsets, a new recordset containing all records present in either source * ``set1 & set2`` returns the intersection of two recordsets, a new recordset containing only records present in both sources * ``set1 - set2`` returns a new recordset containing only records of ``set1`` which are *not* in ``set2`` Recordsets are iterable so the usual Python tools are available for transformation (:func:`python:map`, :func:`python:sorted`, :func:`~python:itertools.ifilter`, ...) however these return either a :class:`python:list` or an :term:`python:iterator`, removing the ability to call methods on their result, or to use set operations. Recordsets therefore provide the following operations returning recordsets themselves (when possible): Filter '''''' .. automethod:: Model.filtered .. automethod:: Model.filtered_domain Map ''' .. automethod:: Model.mapped .. note:: Since V13, multi-relational field access is supported and works like a mapped call: .. code-block:: python3 records.partner_id # == records.mapped('partner_id') records.partner_id.bank_ids # == records.mapped('partner_id.bank_ids') records.partner_id.mapped('name') # == records.mapped('partner_id.name') Sort '''' .. automethod:: Model.sorted .. _reference/orm/inheritance: Inheritance and extension ========================= Odoo provides three different mechanisms to extend models in a modular way: * creating a new model from an existing one, adding new information to the copy but leaving the original module as-is * extending models defined in other modules in-place, replacing the previous version * delegating some of the model's fields to records it contains .. image:: ../images/inheritance_methods.png :align: center Classical inheritance --------------------- When using the :attr:`~odoo.models.Model._inherit` and :attr:`~odoo.models.Model._name` attributes together, Odoo creates a new model using the existing one (provided via :attr:`~odoo.models.Model._inherit`) as a base. The new model gets all the fields, methods and meta-information (defaults & al) from its base. .. code-block:: python class Inheritance0(models.Model): _name = 'inheritance.0' _description = 'Inheritance Zero' name = fields.Char() def call(self): return self.check("model 0") def check(self, s): return "This is {} record {}".format(s, self.name) class Inheritance1(models.Model): _name = 'inheritance.1' _inherit = 'inheritance.0' _description = 'Inheritance One' def call(self): return self.check("model 1") and using them:: a = env['inheritance.0'].create({'name': 'A'}) b = env['inheritance.1'].create({'name': 'B'}) a.call() b.call() will yield: "This is model 0 record A" "This is model 1 record B" the second model has inherited from the first model's ``check`` method and its ``name`` field, but overridden the ``call`` method, as when using standard :ref:`Python inheritance `. Extension --------- When using :attr:`~odoo.models.Model._inherit` but leaving out :attr:`~odoo.models.Model._name`, the new model replaces the existing one, essentially extending it in-place. This is useful to add new fields or methods to existing models (created in other modules), or to customize or reconfigure them (e.g. to change their default sort order):: class Extension0(models.Model): _name = 'extension.0' _description = 'Extension zero' name = fields.Char(default="A") class Extension1(models.Model): _inherit = 'extension.0' description = fields.Char(default="Extended") .. code-block:: python3 record = env['extension.0'].create({}) record.read()[0] will yield:: {'name': "A", 'description': "Extended"} .. note:: It will also yield the various :ref:`automatic fields ` unless they've been disabled Delegation ---------- The third inheritance mechanism provides more flexibility (it can be altered at runtime) but less power: using the :attr:`~odoo.models.Model._inherits` a model *delegates* the lookup of any field not found on the current model to "children" models. The delegation is performed via :class:`~odoo.fields.Reference` fields automatically set up on the parent model. The main difference is in the meaning. When using Delegation, the model **has one** instead of **is one**, turning the relationship in a composition instead of inheritance:: class Screen(models.Model): _name = 'delegation.screen' _description = 'Screen' size = fields.Float(string='Screen Size in inches') class Keyboard(models.Model): _name = 'delegation.keyboard' _description = 'Keyboard' layout = fields.Char(string='Layout') class Laptop(models.Model): _name = 'delegation.laptop' _description = 'Laptop' _inherits = { 'delegation.screen': 'screen_id', 'delegation.keyboard': 'keyboard_id', } name = fields.Char(string='Name') maker = fields.Char(string='Maker') # a Laptop has a screen screen_id = fields.Many2one('delegation.screen', required=True, ondelete="cascade") # a Laptop has a keyboard keyboard_id = fields.Many2one('delegation.keyboard', required=True, ondelete="cascade") .. code-block:: python3 record = env['delegation.laptop'].create({ 'screen_id': env['delegation.screen'].create({'size': 13.0}).id, 'keyboard_id': env['delegation.keyboard'].create({'layout': 'QWERTY'}).id, }) record.size record.layout will result in:: 13.0 'QWERTY' and it's possible to write directly on the delegated field:: record.write({'size': 14.0}) .. warning:: when using delegation inheritance, methods are *not* inherited, only fields .. warning:: * `_inherits` is more or less implemented, avoid it if you can; * chained `_inherits` is essentially not implemented, we cannot guarantee anything on the final behavior. Fields Incremental Definition ----------------------------- A field is defined as class attribute on a model class. If the model is extended, one can also extend the field definition by redefining a field with the same name and same type on the subclass. In that case, the attributes of the field are taken from the parent class and overridden by the ones given in subclasses. For instance, the second class below only adds a tooltip on the field ``state``:: class First(models.Model): _name = 'foo' state = fields.Selection([...], required=True) class Second(models.Model): _inherit = 'foo' state = fields.Selection(help="Blah blah blah") .. _reference/exceptions: Error management ================ .. automodule:: odoo.exceptions :members: AccessDenied, AccessError, CacheMiss, MissingError, RedirectWarning, UserError, ValidationError