Lesson 6: Building applications

Driver setup

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

Managing databases

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)
```

Sessions and transactions

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()
```

Executing queries

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)
```

Processing results

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>
}

Further learning

Lesson 7: Understanding query patterns

Learn how to build query patterns utilising advanced elements of TypeQL syntax, and how queries are resolved by TypeDB.

Python Driver: Reference

Explore the comprehensive API reference for the official TypeDB Python driver.

Drivers: Overview

Explore the docs for all the official TypeDB drivers, including installation guides, tutorials, and API references.

Learning Center