Transaction object

class Transaction(connection, node_factory)

Representation of a database transaction and entrypoint for global tree operations.

Parameters:

• connection (Connection) – Postgres connection object. Its autocommit attribute will be set to False.
• node_factory (object) – Factory class for creating node objects

clear()

Empty database tables.

commit()

Write changes to databases. See commit() .

get_node(node_id)

Get node with given database ID.

Parameters:node_id (int) – Database ID

get_nodes_by_property_dict(query)

Get a set of nodes which have all key/value pairs of query in their properties. Inherited properties are not considered.

Parameters:query (dict) – The dictionary to search for

get_nodes_by_property_key(key)

Get a set of nodes which have a property named key in their properties. Inherited properties are not considered.

Parameters:key (str) – The key to search for

get_nodes_by_property_value(key, value)

Get a set of nodes which have a property key with value value. Inherited properties are not considered.

Parameters:

• key (str) – The key to search for
• value (object) – The exact value to sarch for

get_root_node()

Get root node if exists, other None.

get_tree_size()

Get amount of nodes inside the tree.

insert_root_node(properties=None)

Create root node, then get it.

Parameters:properties (dict) – Inheritable key/value pairs (see Property functions)

install()

Create tables and trigger functions in database.

is_compatible_postgres_version()

Determine whether PostgreSQL server version is compatible with libtree.

print_tree()

Simple function to print tree structure to stdout.

rollback()

Discard changes. See rollback() .

uninstall()

Remove libtree tables from database.