DAO module

Quick Start

For a quick start and a high level description of the usage of this module, refer to Creating your DAO Class.

Module Documentation

Module for Data Access Objects implementation

nova_api.dao.camel_to_snake(name: str)[source]

Converts a camel case name to snake case.

Parameters:name – String in camel case to be converted
Returns:String in snake case
nova_api.dao.is_valid_uuidv4(id_: str) → bool[source]

Checks that the id_ is indeed a UUIDv4 valid string without dashes.

Parameters:id – The ID to validate.
Returns:True if id_ is an UUIDv4, False otherwise.

GenericDAO

class nova_api.dao.GenericDAO(fields: dict = None, return_class: Type[nova_api.entity.Entity] = <class 'nova_api.entity.Entity'>, prefix: str = None)[source]

Interface class for the implementation of Data Access Objects.

__init__(fields: dict = None, return_class: Type[nova_api.entity.Entity] = <class 'nova_api.entity.Entity'>, prefix: str = None) → None[source]

Initialize self. See help(type(self)) for accurate signature.

__weakref__

list of weak references to the object (if defined)

close()[source]

Closes the connection to the database

Returns:None
create(entity: nova_api.entity.Entity) → str[source]

Creates a new row in the database with data from entity.

Raises:NotEntityException – Raised if the entity argument

is not of the return_class of this DAO :raises DuplicateEntityException: Raised if an entity with the same ID exists in the database already.

Parameters:entity – The instance to save in the database.
Returns:The entity uuid.
get(id_: str) → Optional[nova_api.entity.Entity][source]

Recovers and entity with id_ from the database. The id_ must be the nova_api generated id_ which is a 32-char uuid v4.

Raises:
Parameters:

id – The UUID of the instance to recover
Returns:

None if no instance is found or a return_class instance if found
get_all(length: int = 20, offset: int = 0, filters: dict = None) -> (<class 'int'>, typing.List[nova_api.entity.Entity])[source]

Recovers all instances that match the given filters up to the length specified starting from the offset given.

The filters should be given as a dictionary, available keys are the return_class attributes. The values may be only the desired value or a list with the comparator in the first position and the value in the second.

Example

>>> dao.get_all(length=50, offset=0,
...             filters={"birthday":[">", "1/1/1998"],
...                      "name":"John"})
(2, [ent1, ent2])
Parameters:
  • length – The number of items to select
  • offset – The number of items to skip before starting to select
  • filters – A dict with the filters to use. The key must be a valid attribute in the entity and the value may either be an specific value or a list with two elements: an operator and a value,

respectively. :return: A tuple with the totol number of entities in the database and a list of the matched results.

remove(entity: nova_api.entity.Entity = None, filters: dict = None) → int[source]

Removes entities from database. May be called either with an instance of return_class or a dict of filters. *If both are passed, the instance will be removed and the filters won’t be considered.*Invalid filters won’t be considered.

Raises:
Parameters:
  • entity – return_class instance to delete.
  • filters – Filters to apply to delete query in dict format as

specified by _generate_filters :return: Number of affected rows.

update(entity: nova_api.entity.Entity) → str[source]

Updates an entity on the database.

Raises:
Parameters:

entity – The entity with updated values to update on the database.
Returns:

The id_ of the updated entity.

GenericSQLDAO

class nova_api.dao.generic_sql_dao.GenericSQLDAO(database_type: Type[nova_api.persistence.PersistenceHelper] = None, database_instance: nova_api.persistence.PersistenceHelper = None, table: str = None, fields: dict = None, return_class: Type[nova_api.entity.Entity] = <class 'nova_api.entity.Entity'>, prefix: str = None, **kwargs)[source]

SQL implementation for the GenericDAO interface

__class__

alias of abc.ABCMeta

__delattr__

Implement delattr(self, name).

__dir__()

Default dir() implementation.

__eq__

Return self==value.

__format__()

Default object formatter.

__ge__

Return self>=value.

__getattribute__

Return getattr(self, name).

__gt__

Return self>value.

__hash__

Return hash(self).

__init__(database_type: Type[nova_api.persistence.PersistenceHelper] = None, database_instance: nova_api.persistence.PersistenceHelper = None, table: str = None, fields: dict = None, return_class: Type[nova_api.entity.Entity] = <class 'nova_api.entity.Entity'>, prefix: str = None, **kwargs) → None[source]

Initialize self. See help(type(self)) for accurate signature.

__init_subclass__()

This method is called when a class is subclassed.

The default implementation does nothing. It may be overridden to extend subclasses.

__le__

Return self<=value.

__lt__

Return self<value.

__ne__

Return self!=value.

__new__()

Create and return a new object. See help(type) for accurate signature.

__reduce__()

Helper for pickle.

__reduce_ex__()

Helper for pickle.

__repr__

Return repr(self).

__setattr__

Implement setattr(self, name, value).

__sizeof__()

Size of object in memory, in bytes.

__str__

Return str(self).

__subclasshook__()

Abstract classes can override this to customize issubclass().

This is invoked early on by abc.ABCMeta.__subclasscheck__(). It should return True, False or NotImplemented. If it returns NotImplemented, the normal algorithm is used. Otherwise, it overrides the normal algorithm (and the outcome is cached).

__weakref__

list of weak references to the object (if defined)

close() → None[source]

Closes the connection to the database

Returns:None
create(entity: nova_api.entity.Entity) → str[source]

Creates a new row in the database with data from entity.

Raises:NotEntityException – Raised if the entity argument

is not of the return_class of this DAO :raises DuplicateEntityException: Raised if an entity with the same ID exists in the database already.

Parameters:entity – The instance to save in the database.
Returns:The entity uuid.
create_table_if_not_exists() → None[source]

Creates the table in the database based on the return_class attributes. The types used in the database will be inferred through predict_db_types or through the field metadata in the “type” key.

Returns:None
get(id_: str) → Optional[nova_api.entity.Entity][source]

Recovers one entity with id_ from the database.

The id_ must be the nova_api generated id_ which is a 32-char uuid v4.

Raises:
Parameters:

id – The UUID of the instance to recover
Returns:

None if no instance is found or a return_class instance if found
get_all(length: int = 20, offset: int = 0, filters: dict = None) -> (<class 'int'>, typing.List[nova_api.entity.Entity])[source]
Recovers all instances that match the given filters up to the
length specified starting from the offset given.

The filters should be given as a dictionary, available keys are the return_class attributes. The values may be only the desired value or a list with the comparator in the first position and the value in the second.

Example

>>> dao.get_all(length=50, offset=0,
...             filters={"birthday":[">", "1/1/1998"],
...                      "name":"John"})
(2, [ent1, ent2])
Parameters:
  • length – The number of items to select
  • offset – The number of items to skip before starting to select
  • filters – A dict with the filters to use. The key must be a valid attribute in the entity and the value may either be an specific value or a list with two elements: an operator and a value, respectively.
Returns:

A tuple with the totol number of entities in the database and a list of the matched results.
remove(entity: nova_api.entity.Entity = None, filters: dict = None) → int[source]

Removes entities from database. May be called either with an instance of return_class or a dict of filters. *If both are passed, the instance will be removed and the filters won’t be considered.*Invalid filters won’t be considered.

Raises:
Parameters:
  • entity – return_class instance to delete.
  • filters – Filters to apply to delete query in dict format as specified by generate_filters
Returns:

Number of affected rows.
update(entity: nova_api.entity.Entity) → str[source]

Updates an entity on the database.

Raises:
Parameters:

entity – The entity with updated values to update on the database.
Returns:

The id_ of the updated entity.

MongoDAO

class nova_api.dao.mongo_dao.MongoDAO(database='default', fields: dict = None, collection: str = None, return_class: Type[nova_api.entity.Entity] = <class 'nova_api.entity.Entity'>, prefix: str = None, host: str = 'localhost', user: str = 'root', password: str = 'root', database_instance=None)[source]

Mongo implementation for the GenericDAO interface

__class__

alias of abc.ABCMeta

__delattr__

Implement delattr(self, name).

__dir__()

Default dir() implementation.

__eq__

Return self==value.

__format__()

Default object formatter.

__ge__

Return self>=value.

__getattribute__

Return getattr(self, name).

__gt__

Return self>value.

__hash__

Return hash(self).

__init__(database='default', fields: dict = None, collection: str = None, return_class: Type[nova_api.entity.Entity] = <class 'nova_api.entity.Entity'>, prefix: str = None, host: str = 'localhost', user: str = 'root', password: str = 'root', database_instance=None) → None[source]

Initialize self. See help(type(self)) for accurate signature.

__init_subclass__()

This method is called when a class is subclassed.

The default implementation does nothing. It may be overridden to extend subclasses.

__le__

Return self<=value.

__lt__

Return self<value.

__ne__

Return self!=value.

__new__()

Create and return a new object. See help(type) for accurate signature.

__reduce__()

Helper for pickle.

__reduce_ex__()

Helper for pickle.

__repr__

Return repr(self).

__setattr__

Implement setattr(self, name, value).

__sizeof__()

Size of object in memory, in bytes.

__str__

Return str(self).

__subclasshook__()

Abstract classes can override this to customize issubclass().

This is invoked early on by abc.ABCMeta.__subclasscheck__(). It should return True, False or NotImplemented. If it returns NotImplemented, the normal algorithm is used. Otherwise, it overrides the normal algorithm (and the outcome is cached).

__weakref__

list of weak references to the object (if defined)

close()[source]

Closes the connection to the database

Returns:None
create(entity: nova_api.entity.Entity) → str[source]

Creates a new row in the database with data from entity.

Raises:NotEntityException – Raised if the entity argument

is not of the return_class of this DAO :raises DuplicateEntityException: Raised if an entity with the same ID exists in the database already.

Parameters:entity – The instance to save in the database.
Returns:The entity uuid.
get(id_: str) → Optional[nova_api.entity.Entity][source]

Recovers and entity with id_ from the database. The id_ must be the nova_api generated id_ which is a 32-char uuid v4.

Raises:
Parameters:

id – The UUID of the instance to recover
Returns:

None if no instance is found or a return_class instance if found
get_all(length: int = 20, offset: int = 0, filters=None) -> (<class 'int'>, typing.List[nova_api.entity.Entity])[source]

Recovers all instances that match the given filters up to the length specified starting from the offset given.

The filters should be given as a dictionary, available keys are the return_class attributes. The values may be only the desired value or a list with the comparator in the first position and the value in the second.

Example:
>>> dao.get_all(length=50, offset=0,
...             filters={"birthday":[">", "1/1/1998"],
...                      "name":"John"})
(2, [ent1, ent2])
Parameters:
  • length – The number of items to select
  • offset – The number of items to skip before starting to select
  • filters – A dict with the filters to use. The key must be a valid attribute in the entity and the value may either be an specific value or a list with two elements: an operator and a value,

respectively. :return: A tuple with the totol number of entities in the database and a list of the matched results.

remove(entity: nova_api.entity.Entity = None, filters: dict = None) → int[source]

Removes entities from database. May be called either with an instance of return_class or a dict of filters. *If both are passed, the instance will be removed and the filters won’t be considered.*Invalid filters won’t be considered.

Raises:
Parameters:
  • entity – return_class instance to delete.
  • filters – Filters to apply to delete query in dict format as

specified by _generate_filters :return: Number of affected rows.

update(entity: nova_api.entity.Entity) → str[source]

Updates an entity on the database.

Raises:
Parameters:

entity – The entity with updated values to update on the database.
Returns:

The id_ of the updated entity.