Lesson 6: Building applications

The official TypeDB Python driver package can be installed with:

pip install typedb-driver

The following classes must be imported in order to use the Python driver in any codebase:

from typedb.driver import TypeDB, SessionType, TransactionType
from typedb.api.connection.credential import TypeDBCredential

The TypeDB.core_driver method is used to instantiate a new driver object.

driver: TypeDBDriver = TypeDB.core_driver(ADDRESS)

The TypeDBDriver.databases property is used to access database management controls.

The TypeDBDriver.databases.create method is used to create a new database.

driver.databases.create(DATABASE)

The TypeDBDriver.session method is used to instantiate a new session object. The session type is specified using the DATA and SCHEMA values of the SessionType enum.

session: TypeDBSession = driver.session(DATABASE, SessionType.DATA)

Schema sessions are locking: only one can be opened at any time per database, and data writes cannot be performed in any active session while a schema session is open.

The TypeDBSession.transaction method is used to instantiate a new transaction object. The transaction type is specified using the READ and WRITE value of the TransactionType enum.

transaction: TypeDBTransaction = session.transaction(TransactionType.READ)

Driver, session, and transaction objects should always be instantiated using a context manager so that their destructors are called automatically.

with TypeDB.core_driver(ADDRESS) as driver:
    with driver.session(DATABASE, SessionType.DATA) as session:
        with session.transaction(TransactionType.READ) as transaction:
            # code goes here

The TypeDBTransaction.commit method is used to commit a transaction.

transaction.commit()

The TypeDBTransaction.query property is used to access query execution methods.

The TypeDBTransaction.query.fetch method is used to execute Fetch queries. It returns an iterator of results.

results: Iterator[Dict] = transaction.query.fetch(QUERY)

The TypeDBTransaction.query.insert method is used to execute Insert queries.

transaction.query.insert(QUERY)

The TypeDBTransaction.query.delete method is used to execute Delete queries.

transaction.query.delete(QUERY)

The TypeDBTransaction.query.update method is used to execute Update queries.

transaction.query.update(QUERY)

The TypeDBTransaction.query.define method is used to execute Define queries.

transaction.query.define(QUERY)

Each result of a Fetch query is returned as a JSON-style nested dictionary. The top-level dictionary has fields corresponding to the variables in the fetch clause. The second-level dictionary has fields corresponding to the attributes of those variables, in addition to a type field containing the type of the variable.

Every attribute retrieved as part of a result has the following format:

{
    'type': {
        'value_type': <attribute value type>,
        'root': 'attribute',
        'label': <attribute type label>
    },
    'value': <attribute value>
}

Every type retrieved as part of a result has the following format:

{
    'root': <'entity' or 'relation'>,
    'label': <entity or relation type label>
}