:banner: banners/flectra_orm_api.jpg .. _reference/orm: ======= ORM API ======= Recordsets ========== This page documents the New API added in Flectra 1.0 which should be the primary development API going forward. 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(models.Model): _name = 'a.model' def a_method(self): # self can be anywhere 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, but only on singletons (single-record recordsets). 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 Trying to read or write a field on multiple records will raise an error. Accessing a relational field (:class:`~flectra.fields.Many2one`, :class:`~flectra.fields.One2many`, :class:`~flectra.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:`~flectra.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}) Record cache and prefetching ---------------------------- Flectra 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, Flectra *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 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 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`` 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): :meth:`~flectra.models.Model.filtered` 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 records.filtered("partner_id.is_company") :meth:`~flectra.models.Model.sorted` 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) :meth:`~flectra.models.Model.mapped` 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 records.mapped('name') # returns a recordset of partners record.mapped('partner_id') # returns the union of all partner banks, with duplicates removed record.mapped('partner_id.bank_ids') Environment =========== The :class:`~flectra.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:`~flectra.models.Model.env` and gives access to the current user (:attr:`~flectra.api.Environment.user`), the cursor (:attr:`~flectra.api.Environment.cr`) or the context (:attr:`~flectra.api.Environment.context`):: >>> 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) Altering the environment ------------------------ The environment can be customized from a recordset. This returns a new version of the recordset using the altered environment. :meth:`~flectra.models.Model.sudo` 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') env['res.partner'].sudo(public).search([]) :meth:`~flectra.models.Model.with_context` #. 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 env['res.partner'].with_context(tz=a_tz).find_or_create(email_address) :meth:`~flectra.models.Model.with_env` replaces the existing environment entirely Common ORM methods ================== .. maybe these clarifications/examples should be in the APIDoc? :meth:`~flectra.models.Model.search` Takes a :ref:`search domain `, 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 'Agrolait' .. tip:: to just check if any record matches a domain, or count the number of records which do, use :meth:`~flectra.models.Model.search_count` :meth:`~flectra.models.Model.create` Takes a number of field values, and returns a recordset containing the record created:: >>> self.create({'name': "New Name"}) res.partner(78) :meth:`~flectra.models.Model.write` Takes a number of field values, writes them to all the records in its recordset. Does not return anything:: self.write({'name': "Newer Name"}) :meth:`~flectra.models.Model.browse` Takes a database id or a list of ids and returns a recordset, useful when record ids are obtained from outside Flectra (e.g. round-trip through external system):: >>> self.browse([7, 18, 12]) res.partner(7, 18, 12) :meth:`~flectra.models.Model.exists` 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:: records.may_remove_some() # only keep records which were not deleted records = records.exists() :meth:`~flectra.api.Environment.ref` Environment method returning the record matching a provided :term:`external id`:: >>> env.ref('base.group_public') res.groups(2) :meth:`~flectra.models.Model.ensure_one` checks that the recordset is a singleton (only contains a single record), raises an error otherwise:: records.ensure_one() # 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 flectra import models, fields class AModel(models.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 value:: def compute_default_value(self): return self.get_value() a_field = fields.Char(default=compute_default_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 :func:`~flectra.api.depends`:: from flectra 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)] * 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') @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 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) 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 added. * computed fields are automatically checked and recomputed, they do not need an ``onchange`` * for non-computed fields, the :func:`~flectra.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:: 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. .. 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 Low-level SQL ------------- The :attr:`~flectra.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:`~flectra.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:`~flectra.api.Environment.invalidate_all` method of the :class:`~flectra.api.Environment` object. .. _reference/orm/model: Model Reference =============== .. - can't get autoattribute to import docstrings, so use regular attribute - no autoclassmethod .. currentmodule:: flectra.models .. autoclass:: flectra.models.Model .. rubric:: Structural attributes .. attribute:: _name business object name, in dot-notation (in module namespace) .. attribute:: _rec_name Alternative field to use as name, used by osv’s name_get() (default: ``'name'``) .. attribute:: _inherit * If :attr:`._name` is set, names of parent models to inherit from. Can be a ``str`` if inheriting from a single parent * If :attr:`._name` is unset, name of a single model to extend in-place See :ref:`reference/orm/inheritance`. .. attribute:: _order Ordering field when searching without an ordering specified (default: ``'id'``) :type: str .. attribute:: _auto Whether a database table should be created (default: ``True``) If set to ``False``, override :meth:`.init` to create the database table .. attribute:: _table Name of the table backing the model created when :attr:`~flectra.models.Model._auto`, automatically generated by default. .. attribute:: _inherits dictionary mapping the _name of the parent business objects to the names of the corresponding foreign key fields to use:: _inherits = { 'a.model': 'a_field_id', 'b.model': 'b_field_id' } implements composition-based inheritance: the new model exposes all the fields of the :attr:`~flectra.models.Model._inherits`-ed model but stores none of them: the values themselves remain stored on the linked record. .. warning:: if the same field is defined on multiple :attr:`~flectra.models.Model._inherits`-ed .. attribute:: _constraints list of ``(constraint_function, message, fields)`` defining Python constraints. The fields list is indicative use :func:`~flectra.api.constrains` .. attribute:: _sql_constraints list of ``(name, sql_definition, message)`` triples defining SQL constraints to execute when generating the backing table .. attribute:: _parent_store Alongside :attr:`~.parent_left` and :attr:`~.parent_right`, sets up a `nested set `_ to enable fast hierarchical queries on the records of the current model (default: ``False``) :type: bool .. rubric:: CRUD .. automethod:: create .. automethod:: browse .. automethod:: unlink .. automethod:: write .. automethod:: read .. automethod:: read_group .. rubric:: Searching .. automethod:: search .. automethod:: search_count .. automethod:: name_search .. rubric:: Recordset operations .. autoattribute:: ids .. automethod:: ensure_one .. automethod:: exists .. automethod:: filtered .. automethod:: sorted .. automethod:: mapped .. rubric:: Environment swapping .. automethod:: sudo .. automethod:: with_context .. automethod:: with_env .. rubric:: Fields and views querying .. automethod:: fields_get .. automethod:: fields_view_get .. rubric:: Miscellaneous methods .. automethod:: default_get .. automethod:: copy .. automethod:: name_get .. automethod:: name_create .. _reference/orm/model/automatic: .. rubric:: Automatic fields .. attribute:: id Identifier :class:`field ` .. attribute:: _log_access Whether log access fields (``create_date``, ``write_uid``, ...) should be generated (default: ``True``) .. attribute:: create_date Date at which the record was created :type: :class:`~flectra.field.Datetime` .. attribute:: create_uid Relational field to the user who created the record :type: ``res.users`` .. attribute:: write_date Date at which the record was last modified :type: :class:`~flectra.field.Datetime` .. attribute:: write_uid Relational field to the last user who modified the record :type: ``res.users`` .. rubric:: 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:`~._rec_name`, used to display records in context where a representative "naming" is necessary. :type: :class:`~flectra.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 :type: :class:`~flectra.fields.Boolean` .. attribute:: sequence Alterable ordering criteria, allows drag-and-drop reordering of models in list views :type: :class:`~flectra.fields.Integer` .. attribute:: state lifecycle stages of the object, used by the ``states`` attribute on :class:`fields ` :type: :class:`~flectra.fields.Selection` .. attribute:: parent_id used to order records in a tree structure and enables the ``child_of`` operator in domains :type: :class:`~flectra.fields.Many2one` .. attribute:: parent_left used with :attr:`~._parent_store`, allows faster tree structure access .. attribute:: parent_right see :attr:`~.parent_left` .. _reference/orm/decorators: Method decorators ================= .. automodule:: flectra.api :members: multi, model, depends, constrains, onchange, returns, one, v7, v8 .. _reference/orm/fields: Fields ====== .. _reference/orm/fields/basic: Basic fields ------------ .. autodoc documents descriptors as attributes, even for the *definition* of descriptors. As a result automodule:: flectra.fields lists all the field classes as attributes without providing inheritance info or methods (though we don't document methods as they're not useful for "external" devs) (because we don't support pluggable field types) (or do we?) .. autoclass:: flectra.fields.Field .. autoclass:: flectra.fields.Char :show-inheritance: .. autoclass:: flectra.fields.Boolean :show-inheritance: .. autoclass:: flectra.fields.Integer :show-inheritance: .. autoclass:: flectra.fields.Float :show-inheritance: .. autoclass:: flectra.fields.Text :show-inheritance: .. autoclass:: flectra.fields.Selection :show-inheritance: .. autoclass:: flectra.fields.Html :show-inheritance: .. autoclass:: flectra.fields.Date :show-inheritance: :members: today, context_today, from_string, to_string .. autoclass:: flectra.fields.Datetime :show-inheritance: :members: now, context_timestamp, from_string, to_string .. _reference/orm/fields/relational: Relational fields ----------------- .. autoclass:: flectra.fields.Many2one :show-inheritance: .. autoclass:: flectra.fields.One2many :show-inheritance: .. autoclass:: flectra.fields.Many2many :show-inheritance: .. autoclass:: flectra.fields.Reference :show-inheritance: .. _reference/orm/inheritance: Inheritance and extension ========================= Flectra 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:`~flectra.models.Model._inherit` and :attr:`~flectra.models.Model._name` attributes together, Flectra creates a new model using the existing one (provided via :attr:`~flectra.models.Model._inherit`) as a base. The new model gets all the fields, methods and meta-information (defaults & al) from its base. .. literalinclude:: ../../flectra/addons/test_documentation_examples/inheritance.py :language: python :lines: 5- and using them: .. literalinclude:: ../../flectra/addons/test_documentation_examples/tests/test_inheritance.py :language: python :lines: 10,11,14,19 will yield: .. literalinclude:: ../../flectra/addons/test_documentation_examples/tests/test_inheritance.py :language: text :lines: 16,21 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:`~flectra.models.Model._inherit` but leaving out :attr:`~flectra.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): .. literalinclude:: ../../flectra/addons/test_documentation_examples/extension.py :language: python :lines: 5- .. literalinclude:: ../../flectra/addons/test_documentation_examples/tests/test_extension.py :language: python :lines: 8,13 will yield: .. literalinclude:: ../../flectra/addons/test_documentation_examples/tests/test_extension.py :language: text :lines: 11 .. 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:`~flectra.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:`~flectra.fields.Reference` fields automatically set up on the parent model: .. literalinclude:: ../../flectra/addons/test_documentation_examples/delegation.py :language: python :lines: 5- .. literalinclude:: ../../flectra/addons/test_documentation_examples/tests/test_delegation.py :language: python :lines: 11-14,23,28 will result in: .. literalinclude:: ../../flectra/addons/test_documentation_examples/tests/test_delegation.py :language: text :lines: 25,30 and it's possible to write directly on the delegated field: .. literalinclude:: ../../flectra/addons/test_documentation_examples/tests/test_delegation.py :language: python :lines: 45 .. warning:: when using delegation inheritance, methods are *not* inherited, only fields .. _reference/orm/domains: 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:`~flectra.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. Takes the semantics of the model into account (i.e following the relationship field named by :attr:`~flectra.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. .. tip:: Mostly to negate combinations of criteria :class: aphorism 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)