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ThingsDB Connector

Project description

CI Release Version

Python connector for ThingsDB

This library requires Python 3.6 or higher.



Installation

Just use pip:

pip install python-thingsdb

Or, clone the project and use setup.py:

python setup.py install

Quick usage

import asyncio
from thingsdb.client import Client

async def hello_world():
    client = Client()

    # replace `localhost` with your ThingsDB server address
    await client.connect('localhost')

    try:
        # replace `admin` and `pass` with your username and password
        # or use a valid token string
        await client.authenticate('admin', 'pass')

        # perform the hello world code...
        print(await client.query('''
            "Hello World!";
        ''')

    finally:
        # the will close the client in a nice way
        client.close()
        await client.wait_closed()

# run the hello world example
asyncio.get_event_loop().run_until_complete(hello_world())

Client

This is an client using asyncio which can be used for running queries to ThingsDB.

thingsdb.client.Client(
    auto_reconnect: bool = True,
    ssl: Optional[Union[bool, ssl.SSLContext]] = None,
    loop: Optional[asyncio.AbstractEventLoop] = None
) -> Client

Initialize a ThingsDB client

Args

  • auto_reconnect (bool, optional): When set to True, the client will automatically reconnect when a connection is lost. If set to False and the connection gets lost, one may call the reconnect() method to make a new connection. The auto-reconnect option will listen to node changes and automatically start a reconnect loop if the shutting-down status is received from the node. Defaults to True.
  • ssl (SSLContext or bool, optional): Accepts an ssl.SSLContext for creating a secure connection using SSL/TLS. This argument may simply be set to True in which case a context using ssl.PROTOCOL_TLS is created. Defaults to None.
  • loop (AbstractEventLoop, optional): Can be used to run the client on a specific event loop. If this argument is not used, the default event loop will be used. Defaults to None.

authenticate

async Client().authenticate(
    *auth: Union[str, tuple],
    timeout: Optional[int] = 5
) -> None

Authenticate a ThingsDB connection.

Args

  • *auth (str or (str, str)): Argument auth can be be either a string with a token or a tuple with username and password. (the latter may be provided as two separate arguments
  • timeout (int, optional): Can be be used to control the maximum time in seconds for the client to wait for response on the authentication request. The timeout may be set to None in which case the client will wait forever on a response. Defaults to 5.

close

Client().close() -> None

Close the ThingsDB connection.

This method will return immediately so the connection may not be closed yet after a call to close(). Use the wait_closed() method after calling this method if this is required.

connect

Client().connect(
    host: str,
    port: int = 9200,
    timeout: Optional[int] = 5
) -> asyncio.Future

Connect to ThingsDB.

This method will only create a connection, so the connection is not authenticated yet. Use the authenticate(..) method after creating a connection before using the connection.

Args

  • host (str): A hostname, IP address, FQDN to connect to.
  • port (int, optional): Integer value between 0 and 65535 and should be the port number where a ThingsDB node is listening to for client connections. Defaults to 9200.
  • timeout (int, optional): Can be be used to control the maximum time the client will attempt to create a connection. The timeout may be set to None in which case the client will wait forever on a response. Defaults to 5.

Returns

Future which should be awaited. The result of the future will be set to None when successful.

Do not use this method if the client is already connected. This can be checked with client.is_connected().

connect_pool

Client().connect_pool(
    pool: list,
    *auth: Union[str, tuple]
) -> asyncio.Future

Connect using a connection pool.

When using a connection pool, the client will randomly choose a node to connect to. When a node is going down, it will inform the client so it will automatically re-connect to another node. Connections will automatically authenticate so the connection pool requires credentials to perform the authentication.

Examples

await connect_pool([
    'node01.local',             # address as string
    'node02.local',             # port will default to 9200
    ('node03.local', 9201),     # ..or with an explicit port
], "admin", "pass")

Args

  • pool (list of addresses): Should be an iterable with node address strings, or tuples with address and port combinations in a tuple or list.
  • *auth (str or (str, str)): Argument auth can be be either a string with a token or a tuple with username and password. (the latter may be provided as two separate arguments

Returns

Future which should be awaited. The result of the future will be set to None when successful.

Do not use this method if the client is already connected. This can be checked with client.is_connected().

get_default_scope

Client().get_default_scope() -> str

Get the default scope.

The default scope may be changed with the set_default_scope() method.

Returns

The default scope which is used by the client when no specific scope is specified.

get_event_loop

Client().get_event_loop() -> asyncio.AbstractEventLoop

Can be used to get the event loop.

Returns

The event loop used by the client.

get_rooms

Client().get_rooms() -> tuple

Can be used to get the rooms which are joined by this client.

Returns

A tuple with unique Room instances.

is_connected

Client().is_connected() -> bool

Can be used to check if the client is connected.

Returns

True when the client is connected else False.

query

Client().query(
        code: str,
        scope: Optional[str] = None,
        timeout: Optional[int] = None,
        **kwargs: Any
) -> asyncio.Future

Query ThingsDB.

Use this method to run code in a scope.

Args

  • code (str): ThingsDB code to run.
  • scope (str, optional): Run the code in this scope. If not specified, the default scope will be used. See https://docs.thingsdb.net/v0/overview/scopes/ for how to format a scope.
  • timeout (int, optional): Raise a time-out exception if no response is received within X seconds. If no time-out is given, the client will wait forever. Defaults to None.
  • **kwargs (any, optional): Can be used to inject variable into the ThingsDB code.

Examples

Although we could just as easy have wrote everything in the ThingsDB code itself, this example shows how to use **kwargs for injecting variable into code. In this case the variable book.

res = await client.query(".my_book = book;", book={
    'title': 'Manual ThingsDB'
})

Returns

Future which should be awaited. The result of the future will contain the result of the ThingsDB code when successful.

If the ThingsDB code will return with an exception, then this exception will be translated to a Python Exception which will be raised. See thingsdb.exceptions for all possible exceptions and https://docs.thingsdb.net/v0/errors/ for info on the error codes.

reconnect

async Client().reconnect() -> None

Re-connect to ThingsDB.

This method can be used, even when a connection still exists. In case of a connection pool, a call to reconnect() will switch to another node.

run

Client().run(
    procedure: str,
    *args: Optional[Any],
    scope: Optional[str] = None,
    timeout: Optional[int] = None,
    **kwargs: Any
) -> asyncio.Future

Run a procedure.

Use this method to run a stored procedure in a scope.

Args

  • procedure (str): Name of the procedure to run.
  • *args (any): Arguments which are injected as the procedure arguments. Instead of positional, the arguments may also be parsed using keyword arguments but not both at the same time.
  • scope (str, optional): Run the procedure in this scope. If not specified, the default scope will be used. See https://docs.thingsdb.net/v0/overview/scopes/ for how to format a scope.
  • timeout (int, optional): Raise a time-out exception if no response is received within X seconds. If no time-out is given, the client will wait forever. Defaults to None.
  • **kwargs (any, optional): Arguments which are injected as the procedure arguments. Instead of by name, the arguments may also be parsed using positional arguments but not both at the same time.

Returns

Future which should be awaited. The result of the future will contain the result of the ThingsDB procedure when successful.

If the ThingsDB code will return with an exception, then this exception will be translated to a Python Exception which will be raised. See thingsdb.exceptions for all possible exceptions and https://docs.thingsdb.net/v0/errors/ for info on the error codes.

set_default_scope

Client().set_default_scope(scope: str) -> None

Set the default scope.

Can be used to change the default scope which is initially set to @t.

Args

  • scope (str): Set the default scope. A scope may start with either the / character, or @. Examples: "//stuff", "@:stuff", "/node"

wait_closed

async Client().wait_closed() -> None

Wait for a connection to close.

Can be used after calling the close() method to determine when the connection is actually closed.

Room

Rooms can be implemented to listen for events from ThingsDB rooms.

Se the example code:

from thingsdb.room import Room, event

class Chat(Room):

    @event('msg')
    def on_msg(self, msg):
        print(msg)

This will listen for msg events on a ThingsDB room. To connect out class to a room, you have to initialize the class with a roomId of some ThingsDB code which returns the roomId as integer value. For example:

# Create a chat instance. In this example we initialize our chat with some ThingsDB code
chat = Chat("""//ti
    // Create .chat room if the room does not exist.
    .has('chat') || .chat = room();

    // return the roomId.
    .chat.id();
""")

# Now we can join the room. (we assume that you have a ThingsDB client)
await chat.join(client)

Room Init Args

  • room (int/str): The room Id or ThingsDB code which returns the Id of the room. Examples are 123, '.my_room.id();'
  • scope (str): Collection scope. If no scope is given, the scope will later be set to the default client scope once the room is joined.

Room Methods

Besides implementing an @event handler, a room has also some methods which can be implemented to control or initialize a room.

on_init(self) -> None

Called when a room is joined. This method will be called only once, thus not after a re-connect like the on_join(..) method. This method is guaranteed to be called before the on_join(..) method.

on_join(self) -> None:

Called when a room is joined. Unlike the on_init(..) method, the on_join(..) method will be called again after a re-connect.

This is an async method and usually the best method to perform some ThingsDB queries (if required).

Unless the wait argument to the Room.join(..) function is explicitly set to 0 or None, the first call to this method will finish before the call to Room.join() is returned.

on_leave(self) -> None:

Called after a leave room request. This event is not triggered by ThingsDB when a client disconnects or when a node is shutting down.

on_delete(self) -> None:

Called when the room is removed from ThingsDB.

on_emit(self, event: str, *args) -> None:

Called when no event handler is configured for the event. By default, the on_emit will display a "debug" log message when called to show that no handler for the event is found.

Room Properties

The following properties are available on a room instance. Note that some properties might return None as long as a room is not joined.

Property Description
id Returns the roomId.
scope Returns the scope of the room.
client Returns the associated client of the room.

join

Room().join(client: Client, wait: Optional[float] = 60.0) -> None

Joins the room.

Args

  • client (thingsdb.client.Client): ThingsDB client instance.
  • wait (float): Max time (in seconds) to wait for the first on_join call. If wait is set to 0 or None, the join method will not wait for the first on_join call to happen.

leave

Room().leave() -> None

Leave the room. If the room is not found, a LookupError will be raised.

emit

Room().emit(event: str, *args: Optional[Any],) -> asyncio.Future

Emit an event to a room.

Args

  • event (str): Name of the event to emit.
  • *args (any): Additional argument to send with the event.

Returns

Future which should be awaited. The result of the future will be set to None when successful.

Failed packages

set_package_fail_file(fn: str = '') -> None

Configure a file name to dump the last failed package.

Only the MessagePack data will be stored in this file, not the package header. This is useful for debugging packages which fail to unpack. Note that only a single fail file can be used which is active (or not) for all clients.

When empty (''), a failed package will not be dumped to file.

from thingsdb.client import set_package_fail_file

set_package_fail_file('/tmp/thingsdb-invalid-data.mp')

# When a package is received which fails to unpack, the data from this package
# will be stored to file.

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