[ADD] doc: guide to the new API

Raw API documentation is not sufficient for people to learn the working
principles of the API, especially when they already know the old one. And some
things have changed since the opendays so the presentations don't reflect the
current state of affairs.

Closes #3483
Xavier Morel 2014-11-07 14:42:33 +01:00
parent ce0521aa99
commit e7b6d0bda9
2 changed files with 676 additions and 5 deletions

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@ -13,6 +13,9 @@
``account.invoice_graph``). From within a module, the
:samp:`{module}.` prefix can be left out.
Sometimes referred to as "xml id" or ``xml_id`` as XML-based
:ref:`reference/data` make extensive use of them.
format string
inspired by `jinja variables`_, format strings allow more easily
mixing literal content and computed content (expressions): content

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@ -4,10 +4,678 @@
.. versionadded:: 8.0
Interaction with models and records is performed through recordsets, a sorted
set 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(Model):
_name = 'a.model'
def a_method(self):
# self can be anywhere between 0 records and all records in the
# database
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, but only on singletons (single-record
recordsets). Setting a field's value triggers an update to the database::
>>> record.name
Example Name
>>> record.company_id.name
Company Name
>>> record.name = "Bob"
Trying to read or write a field on multiple records will raise an error.
Accessing a relational field (:class:`~openerp.fields.Many2one`,
:class:`~openerp.fields.One2many`, :class:`~openerp.fields.Many2many`)
*always* returns a recordset, empty if the field is not set.
.. danger::
each assignment to a field triggers a database update, when setting
multiple fields at the same time or setting fields on multiple records
(to the same value), use :meth:`~openerp.models.Model.write`::
# 3 * len(records) database updates
for record in records:
record.a = 1
record.b = 2
record.c = 3
# len(records) database updates
for record in records:
record.write({'a': 1, 'b': 2, 'c': 3})
# 1 database update
records.write({'a': 1, 'b': 2, 'c': 3})
Set operations
Recordsets are immutable, but sets of the same model can be combined using
various set operations, returning new recordsets. Set operations do *not*
preserve order.
.. 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
* ``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``
Other recordset operations
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 these operations returning recordsets themselves
(when possible):
returns a recordset containing only records satisfying the provided
predicate function. The predicate can also be a string to filter by a
field being true or false::
# only keep records whose company is the current user's
records.filtered(lambda r: r.company_id == user.company_id)
# only keep records whose partner is a company
returns a recordset sorted by the provided key function. If no key
is provided, use the model's default sort order::
# sort records by name
records.sorted(key=lambda r: r.name)
applies the provided function to each record in the recordset, returns
a recordset if the results are recordsets::
# returns a list of summing two fields for each record in the set
records.mapped(lambda r: r.field1 + r.field2)
The provided function can be a string to get field values::
# returns a list of names
# returns a recordset of partners
# returns the union of all partner banks, with duplicates removed
The :class:`~openerp.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:`~openerp.models.Model.env` and gives access to the current user
(:attr:`~openerp.api.Environment.user`), the cursor
(:attr:`~openerp.api.Environment.cr`) or the context
>>> records.env
<Environment object ...>
>>> records.env.user
>>> records.env.cr
<Cursor object ...)
When creating a recordset from an other recordset, the environment is
inherited. The environment can be used to get an empty recordset in an
other model, and query that model::
>>> self.env['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)
Altering the environment
The environment can be customized from a recordset. This returns a new
version of the recordset using the altered environment.
creates a new environment with the provided user set, uses the
administrator if none is provided (to bypass access rights/rules in safe
contexts), returns a copy of the recordset it is called on using the
new environment::
# create partner object as administrator
env['res.partner'].sudo().create({'name': "A Partner"})
# list partners visible by the "public" user
public = env.ref('base.public_user')
#. can take a single positional parameter, which replaces the current
environment's context
#. can take any number of parameters by keyword, which are added to either
the current environment's context or the context set during step 1
# look for partner, or create one with specified timezone if none is
# found
replaces the existing environment entirely
Common ORM methods
.. maybe these clarifications/examples should be in the APIDoc?
Takes a :ref:`search domain <reference/orm/domains>`, returns a recordset
of matching records. Can return a subset of matching records (``offset``
and ``limit`` parameters) and be ordered (``order`` parameter)::
>>> # searches the current model
>>> self.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)
>>> self.search([('is_company', '=', True)], limit=1).name
.. tip:: to just check if any record matches a domain, or count the number
of records which do, use
Takes a number of field values, and returns a recordset containing the
record created::
>>> self.create({'name': "New Name"})
Takes a number of field values, writes them to all the records in its
recordset. Does not return anything::
self.write({'name': "Newer Name"})
Takes a database id or a list of ids and returns a recordset, useful when
record ids are obtained from outside Odoo (e.g. round-trip through
external system) or :ref:`when calling methods in the old API
>>> self.browse([7, 18, 12])
res.partner(7, 18, 12])
Returns a new recordset containing only the records which exist in the
database. Can be used to check whether a record (e.g. obtained externally)
still exists::
if not record.exists():
raise Exception("The record has been deleted")
or after calling a method which could have removed some records::
# only keep records which were not deleted
records = records.exists()
Environment method returning the record matching a provided
:term:`external id`::
>>> env.ref('base.group_public')
checks that the recordset is a singleton (only contains a single record),
raises an error otherwise::
# is equivalent to but clearer than:
assert len(records) == 1, "Expected singleton"
Creating Models
Model fields are defined as attributes on the model itself::
from openerp import models, fields
class AModel(Model):
_name = 'a.model.name'
field1 = fields.Char()
.. warning:: this means you can not define a field and a method with the same
name, they will conflict
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="an other field")
For the various field types and parameters, see :ref:`the fields reference
Default values are defined as parameters on fields, either a value::
a_field = fields.Char(default="a value")
or a function called to compute the default value, which should return that
a_field = fields.Char(default=compute_default_value)
def compute_default_value(self):
return self.get_value()
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
from openerp 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::
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
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)]
* 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:
* 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')
@depends('value', 'discount')
def _apply_discount(self):
for record in self:
# compute actual discount from discount percentage
discount = self.value * self.discount
self.discount_value = discount
self.total = self.value - discount
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
nickname = fields.Char(related='user_id.partner_id.name', store=True)
onchange: updating UI on the fly
When a user changes a field's value in a form (but hasn't saved the form yet),
it can be useful to automatically update other fields based on that value
e.g. updating a final total when the tax is changed or a new invoice line is
* computed fields are automatically checked and recomputed, they do not need
an ``onchange``
* for non-computed fields, the :func:`~openerp.api.onchange` decorator is used
to provide new field values::
@api.onchange('field1', 'field2') # if these fields are changed, call method
def check_change(self):
if self.field1 < self.field2:
self.field3 = True
the changes performed during the method are then sent to the client program
and become visible to the user
* Both computed fields and new-API onchanges are automatically called by the
client without having to add them in views
* It is possible to suppress the trigger from a specific field by adding
``on_change="0"`` in a view::
<field name="name" on_change="0"/>
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
.. note::
``onchange`` methods work on virtual records assignment on these records
is not written to the database, just used to know which value to send back
to the client
.. _reference/orm/oldapi:
Old API compatibility
Odoo is currently transitioning from an older (less regular) API, it can be
necessary to manually bridge from one to the other manually:
* RPC layers (both XML-RPC and JSON-RPC) are expressed in terms of the old
API, methods expressed purely in the new API are not available over RPC
* overridable methods may be called from older pieces of code still written
in the old API style
The big differences between the old and new APIs are:
* values of the :class:`~openerp.api.Environment` (cursor, user id and
context) are passed explicitly to methods instead
* record data (:attr:`~openerp.models.Model.ids`) are passed explicitly to
methods, and possibly not passed at all
* methods tend to work on lists of ids instead of recordsets
By default, methods are assumed to use the new API style and are not callable
from the old API style.
.. tip:: calls from the new API to the old API are bridged
:class: aphorism
when using the new API style, calls to methods defined using the old API
are automatically converted on-the-fly, there should be no need to do
anything special::
>>> # method in the old API style
>>> def old_method(self, cr, uid, ids, context=None):
... print ids
>>> # method in the new API style
>>> def new_method(self):
... # system automatically infers how to call the old-style
... # method from the new-style method
... self.old_method()
>>> env[model].browse([1, 2, 3, 4]).new_method()
[1, 2, 3, 4]
Two decorators can expose a new-style method to the old API:
the method is exposed as not using ids, its recordset will generally be
empty. Its "old API" signature is ``cr, uid, *arguments, context``::
def some_method(foo):
# can be called as
old_style_model.some_method(cr, uid, a_value, context=context)
the method is exposed as taking a list of ids (possibly empty), its
"old API" signature is ``cr, uid, ids, *arguments, context``::
def some_method(foo):
# can be called as
old_style_model.some_method(cr, uid, [id1, id2], a_value, context=context)
Because new-style APIs tend to return recordsets and old-style APIs tend to
return lists of ids, there is also a decorator managing this:
the function is assumed to return a recordset, the first parameter should
be the name of the recordset's model or ``self`` (for the current model).
No effect if the method is called in new API style, but transforms the
recordset into a list of ids when called from the old API style::
>>> @api.multi
... @api.returns('self')
... def some_method():
... return self
>>> new_style_model = env['a.model'].browse(1, 2, 3)
>>> new_style_model.some_method()
a.model(1, 2, 3)
>>> old_style_model = pool['a.model']
>>> old_style_model.some_method(cr, uid, [1, 2, 3], context=context)
[1, 2, 3]
Porting from the old API
* methods still written in the old API should be automatically bridged by the
ORM, no need to switch to the old API, just call them as if they were a new
API method. See :ref:`reference/orm/oldapi/bridging` for more details.
* ``search`` returns a recordset, no point in e.g. browsing its result
* ``fields.related`` and ``fields.function`` are replaced by using a normal
field type with either a ``related`` or a ``compute`` parameter
* ``depends`` on field compute methods **must be complete**, it must list
**all** the fields and sub-fields which the compute method uses. It is
better to have too many dependencies (will recompute the field in cases
where that is not needed) than not enough (will forget to recompute the
field and then values will be incorrect)
* **remove** all ``onchange`` methods on computed fields. Computed fields are
automatically re-computed when one of their dependencies is changed, and
that is used to auto-generate ``onchange`` by the client
* the decorators :func:`~openerp.api.model` and :func:`~openerp.api.multi` are
for bridging *when calling from the old API context*, for internal or pure
new-api (e.g. compute) they are useless
* remove :attr:`~openerp.models.Model._default`, replace by ``default=``
parameter on corresponding fields
* if a field's ``string`` is the titlecased version of the field name::
name = fields.Char(string="Name")
it is useless and should be removed
* ``multi`` does not do anything on new API fields use the same ``compute``
methods on all relevant fields for the same result
* provide ``compute``, ``inverse`` and ``search`` methods by name (as a
string), this makes them overridable (removes the need for an intermediate
"trampoline" function)
* double check that all fields and methods have different names, there is no
warning in case of collision (because Python handles it before Odoo sees
* the normal new-api import is ``from openerp import fields, models``. If
compatibility decorators are necessary, use ``from openerp import api,
fields, models``
* avoid the :func:`~openerp.api.one` decorator, it probably does not do what
you expect
* remove explicit definition of :attr:`~openerp.models.Model.create_uid`,
:attr:`~openerp.models.Model.write_uid` and
:attr:`~openerp.models.Model.write_date` fields: they are now created as
regular "legitimate" fields, and can be read and written like any other
field out-of-the-box
* when straight conversion is impossible (semantics can not be bridged) or the
"old API" version is not desirable and could be improved for the new API, it
is possible to use completely different "old API" and "new API"
implementations for the same method name using :func:`~openerp.api.v7` and
:func:`~openerp.api.v8`. The method should first be defined using the
old-API style and decorated with :func:`~openerp.api.v7`, it should then be
re-defined using the exact same name but the new-API style and decorated
with :func:`~openerp.api.v8`. Calls from an old-API context will be
dispatched to the first implementation and calls from a new-API context will
be dispatched to the second implementation. One implementation can call (and
frequently does) call the other by switching context.
.. danger:: using these decorators makes methods extremely difficult to
override and harder to understand and document
* uses of :attr:`~openerp.models.Model._columns` or
:attr:`~openerp.models.Model._all_columns` should be replaced by
:attr:`~openerp.models.Model._fields`, which provides access to instances of
new-style :class:`openerp.fields.Field` instances (rather than old-style
Non-stored computed fields created using the new API style are *not*
available in :attr:`~openerp.models.Model._columns` and can only be
inspected through :attr:`~openerp.models.Model._fields`
* reassigning ``self`` in a method is probably unnecessary and may break
translation introspection
* :class:`~openerp.api.Environment` objects rely on some threadlocal state,
which has to be set up before using them. It is necessary to do so using the
:meth:`openerp.api.Environment.manage` context manager when trying to use
the new API in contexts where it hasn't been set up yet, such as new threads
or a Python interactive environment::
>>> from openerp import api, modules
>>> r = modules.registry.RegistryManager.get('test')
>>> cr = r.cursor()
>>> env = api.Environment(cr, 1, {})
Traceback (most recent call last):
AttributeError: environments
>>> with api.Environment.manage():
... env = api.Environment(cr, 1, {})
... print env['res.partner'].browse(1)
.. _reference/orm/oldapi/bridging:
Automatic bridging of old API methods
When models are initialized, all methods are automatically scanned and bridged
if they look like models declared in the old API style. This bridging makes
them transparently callable from new-API-style methods.
Methods are matched as "old-API style" if their second positional parameter
(after ``self``) is called either ``cr`` or ``cursor``. The system also
recognizes the third positional parameter being called ``uid`` or ``user`` and
the fourth being called ``id`` or ``ids``. It also recognizes the presence of
any parameter called ``context``.
When calling such methods from a new API context, the system will
automatically fill matched parameters from the current
:class:`~openerp.api.Environment` (for :attr:`~openerp.api.Environment.cr`,
:attr:`~openerp.api.Environment.user` and
:attr:`~openerp.api.Environment.context`) or the current recordset (for ``id``
and ``ids``).
In the rare cases where it is necessary, the bridging can be customized by
decorating the old-style method:
* disabling it entirely, by decorating a method with
:func:`~openerp.api.noguess` there will be no bridging and methods will be
called the exact same way from the new and old API styles
* defining the bridge explicitly, this is mostly for methods which are matched
incorrectly (because parameters are named in unexpected ways):
will automatically prepend the current cursor to explicitly provided
parameters, positionally
will automatically prepend the current cursor and user's id to explictly
provided parameters
will automatically prepend the current cursor, user's id and recordset's
ids to explicitly provided parameters
will loop over the current recordset and call the method once for each
record, prepending the current cursor, user's id and record's id to
explicitly provided parameters.
.. danger:: the result of this wrapper is *always a list* when calling
from a new-API context
All of these methods have a ``_context``-suffixed version
(e.g. :func:`~openerp.api.cr_uid_context`) which also passes the current
context *by keyword*.
* dual implementations using :func:`~openerp.api.v7` and
:func:`~openerp.api.v8` will be ignored as they provide their own "bridging"
Low-level SQL
The :attr:`~openerp.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", param1, param2, param3)
Because models use the same cursor and the :class:`~openerp.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).
Clearing caches can be performed using the
:meth:`~openerp.api.Environment.invalidate_all` method of the
:class:`~openerp.api.Environment` object.
.. _reference/orm/model:
Model Reference
.. - can't get autoattribute to import docstrings, so use regular attribute
- no autoclassmethod
@ -121,7 +789,7 @@ Model
.. automethod:: exists
.. automethod:: filtered
.. automethod:: sorted
.. automethod:: update
.. automethod:: mapped
.. rubric:: Environment swapping
@ -234,7 +902,8 @@ Method decorators
.. automodule:: openerp.api
:members: one, multi, model, depends, constrains, onchange, returns
:members: one, multi, model, depends, constrains, onchange, returns,
v7, v8
.. _reference/orm/fields:
@ -499,4 +1168,3 @@ Domain criteria can be combined using logical operators in *prefix* form:
(name is 'ABC')
AND (language is NOT english)
AND (country is Belgium OR Germany)