ORM – object relational mapping

sf – ORM session factory

Module sf defines SessionFactory class which is central point for your ORM mapping and SQL database access providing connections to database.

class summer.sf.SessionProvider

Bases: object

Class to be used as based for providing SqlAlchemy session.

See default implementation in summer.sf.DefaultSessionProvider.

__init__()

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

property engine

Get SqlAlchemy engine implementation.

Returns

SqlAlchemy engine implementation

Return type

sqlalchemy.engine.Engine

property metadata

Get SqlAlchemy metadata.

Returns

SqlAlchemy metadata

Return type

sqlalchemy.Metadata

property sessionmaker

Get SqlAlchemy session factory class.

Returns

SqlAlchemy session factory class

Return type

sqlalchemy.orm.sessionmaker

property declarative_base_class

Get SqlAlchemy declarative_base type. Mixing classical and declarative approaches is possible, if declarative_base type uses the same metadata and engine with classical approach. Creating single instance of single summer.sf.SessionProvider ensures it is the same.

Returns

SqlAlchemy declarative_base type to be used as base class for entities.

Return type

type

__weakref__

list of weak references to the object (if defined)

class summer.sf.DefaultSessionProvider(uri: str, autocommit: bool = False, **engine_kwargs)

Bases: summer.sf.SessionProvider

Default implementation of summer.sf.SessionProvider. Provides access to SqlAlchemy internal objectssession.

See default implementation in summer.sf.DefaultSessionProvider.

__init__(uri: str, autocommit: bool = False, **engine_kwargs)

Parameters

• uri (str) – SqlAlchemy’s uri (ie. connection string)

• autocommit (bool) – SqlAlchemy’s autocommit

• pool_recycle (int) – SqlAlchemy’s pool recycling timeout

property engine

Get SqlAlchemy engine implementation.

Returns

SqlAlchemy engine implementation

Return type

sqlalchemy.engine.Engine

property metadata

Get SqlAlchemy metadata.

Returns

SqlAlchemy metadata

Return type

sqlalchemy.Metadata

property sessionmaker

Get SqlAlchemy session factory class.

Returns

SqlAlchemy session factory class

Return type

sqlalchemy.orm.sessionmaker

property declarative_base_class

Get SqlAlchemy declarative_base type. Mixing classical and declarative approaches is possible, if declarative_base type uses the same metadata and engine with classical approach. Creating single instance of single summer.sf.SessionProvider ensures it is the same.

Returns

SqlAlchemy declarative_base type to be used as base class for entities.

Return type

type

class summer.sf.SessionFactory(session_provider: summer.sf.SessionProvider)

Bases: object

Thread safe SqlAlchemy session provider.

class Local(engine: sqlalchemy.engine.base.Engine, sessionmaker: sqlalchemy.orm.session.sessionmaker)

Bases: _thread._local

Thread local session & connection wrapper.

__init__(engine: sqlalchemy.engine.base.Engine, sessionmaker: sqlalchemy.orm.session.sessionmaker)

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

property sqlalchemy_session

Get current SqlAlchemy session.

Returns

existing of just created SqlAlchemy session.

Return type

sqlalchemy.orm.Session

property autocommit

Delegates to sqlalchemy_session.autocommit().

property connection

Use connection.connection to obtain Python DB API connection.

Returns

current thread-bound SqlAclhemy connection object corresponding to current session’s transactional state.

Return type

sqlalchemy.engine.Connection

property active

Get status of current SqlAlchemy transaction.

Returns

True if transaction is in progress, False otherwise.

Return type

bool

__init__(session_provider: summer.sf.SessionProvider)

Creates SessionFactory instance.

Parameters

uri (str) – SqlAlchemy connection string (including username and password)

property table_definitions

Get current table definitions.

Returns

current TableDefinitions instance

Return type

TableDefinitions

property class_mappings

Get current class mappings.

Returns

current ClassMappings instance

Return type

ClassMappings

property session

Get current thread-local SqlAlchemy session wrapper (creating one, if non-exististent).

Returns

existing or just created SqlAlchemy session wrapper

Return type

SessionFactory.Local

property sqlalchemy_session

Delegates to SessionFactory.Local.sqlalchemy_session().

property connection

Delegates to SessionFactory.Local.connection().

property dialect

Get SqlAlchemy dialect.

Returns

current SqlAlchemy dialect

Return type

sqlalchemy.engine.Dialect

property sqlite_dialect

SQLite is great database for testing or local access, but not designed for multi-threaded/-process applications. Sometimes it is handy to know you are using it to bypass its limitations.

Returns

True if running over sqlite, False otherwise.

Return type

bool

create_schema()

Create database schema using SqlAlchemy. Call once table_definitions are set.

Use with caution – will destroy all your data!

__weakref__

list of weak references to the object (if defined)

class summer.sf.AbstractTableDefinitions

Bases: object

Container for SqlAlchemy table definitions. Registers itself at session factory. A callback class – use to provide table definitions to ORM.

See summer.context.Context.orm_init() method.

define_tables(session_factory: summer.sf.SessionFactory)

Override in subclasses to define database tables.

__weakref__

list of weak references to the object (if defined)

class summer.sf.AbstractClassMappings

Bases: object

Container for SqlAlchemy mappings. Registers itself at session factory. A callback class – use to provide class mappings to ORM.

See summer.context.Context.orm_init() method.

__weakref__

list of weak references to the object (if defined)

create_mappings(session_factory: summer.sf.SessionFactory)

Override in subclasses to define mappings (tables to ORM classes – entities).

dao – ORM data access object support

Provides DAO support.

Base Dao class provides access to Dao.session() and py:meth:Dao.connection properties.

That means that inside any DAO object subclassed from Dao you can access current (thread-bound) SqlAlchemy session simply by accessing Dao.session() and direct connection to database by accessing Dao.connection().

Much more interesting is EntityDao class which is inteded to be used as a base DAO class for your summer.domain.Entity.

class summer.dao.Dao(session_factory: summer.sf.SessionFactory)

Bases: object

Base DAO class.

Provides safe access to thread bound session through session attribute. Alternative is get_session().

__init__(session_factory: summer.sf.SessionFactory)

Creates Dao instance.

Parameters

session_factory (SessionFactory) – session factory to be used

property session

Get current session (bound to current thread).

Returns

current sqlalchemy.orm.Session instance

Return type

Session

property connection

Get current connection (bound to current thread).

Use connection.connection to obtain Python DB API 2.0 connection object.

Returns

current sqlalchemy.engine.Connection instance

Return type

Connection

__weakref__

list of weak references to the object (if defined)

class summer.dao.EntityDao(session_factory: summer.sf.SessionFactory, clazz: Type[E])

Bases: summer.dao.Dao

Base DAO class for persistent classes subclassed from summer.domain.Entity.

Provides basic persistent operations.

Defines another property – query() – access to generic SqlAlchemy query over clazz().

__init__(session_factory: summer.sf.SessionFactory, clazz: Type[E])

Creates EntityDao instance.

Parameters

• session_factory (SessionFactory) – session factory intance to be passed to superclass (Dao)

• clazz (type) – reference to class type

property clazz

Get class type for this dao.

Returns

class for this EntityDao

Return type

type

property query

Get new query instance using clazz().

Returns

query over clazz()

Return type

sqlalchemy.orm.Query

_check_entity(entity: E)

Check if entity is correct.

Parameters

entity (Entity) – entity instance to be checked

_get_result_list(query: sqlalchemy.orm.query.Query, query_filter: summer.domain.Filter) → List[E]

Get list of entities with filter offset applied. Useful for paging.

Parameters

• query (Query) – query to be executed

• query_filter (Filter) – filter to be used for paging

Returns

list of entities using query and paging supplied

Return type

list

get(ident: object) → E

Get entity by Entity.id attribute.

Parameters

ident (object) – primary key for Entity

Returns

entity instance or raise NoResultFound if

none is found

Return type

Entity

save(entity: E) → E

Save an entity.

Parameters

entity (Entity) – entity to be persisted

Returns

persisted instance

Return type

Entity

merge(entity: E) → E

Merge an entity.

Same as save(), but entity is associated with current session if it is not. For example if entity comes from another session (or thread).

Parameters

entity (Entity) – entity to be merged

Returns

persisted instance

Return type

Entity

delete(entity_or_id: object) → E

Delete an entity.

Parameters

entity_or_id (object) – either Entity or its primary key

Returns

just deleted entity instance

Return type

Entity

find(query_filter: summer.domain.Filter) → List[E]

Find collection of entities.

Parameters

query_filter (Filter) – filter with at least paging set

Returns

list of entities using query and paging supplied

Return type

list

get_by_uniq(col_name: str, col_value: object) → E

Get entity by its unique attribute value.

Parameters

• col_name (str) – attribute column name

• col_value (object) – attribute value

Returns

entity instance or raise NoResultFound if

none is found.

Return type

Entity

get_by_uniq_or_none(col_name: str, col_value: object) → E

Get entity by its unique attribute value.

Parameters

• col_name (str) – attribute column name

• col_value (object) – attribute value

Returns

entity instance or None if none is found.

Return type

Entity

class summer.dao.CodeEntityDao(session_factory: summer.sf.SessionFactory, clazz: Type[T])

Bases: summer.dao.EntityDao

Base DAO class for persistent classes subclassed from summer.domain.CodeEntity.

__init__(session_factory: summer.sf.SessionFactory, clazz: Type[T])

Creates CodeEntityDao instance.

Parameters

• session_factory (SessionFactory) – session factory intance to be passed to superclass (Dao)

• clazz (type) – reference to class type

find_map(query_filter: summer.domain.Filter) → Dict[str, T]

Loads the objects into a map by CodeEntity.code attribute used as a map key.

query_filter (Filter): filter with at least paging set

Returns

dictionary of entities using query and paging supplied

Return type

dict

exception summer.dao.DaoException(message: str = None, **kwargs)

Bases: summer.ex.ApplicationException

__init__(message: str = None, **kwargs)

Creates ApplicationException instance.

Parameters

• message (str) – message to be printed

• kwargs – keyword arguments are printed as are, suitable for providing some context (current values of important variables and such.