Database Handler

To implement a database for CVTEngine is necessary to specify the app mode with the new method set_mode.

By default, the app mode is "Development. If the app mode is Development* so the database used is SQLite.

For Sqlite Database you must define the db filename with the arg dbfile in the method set_db.

For Database in production you must define the data base type with dbtype. PyHades Support Postgres and MySQL.

Then, once you set the db you must set the tags that you want to log with the method set_tag

SQLite Database

Usage

>>> from pyhades import PyHades, PyHadesStateMachine, State
>>> from pyhades.models import IntegerType
>>> from pyhades.tags import CVTEngine, TagBinding

>>> app = PyHades()
>>> app.set_mode('Development')
# DB Definition
>>> app.set_db(dbfile="app.db")

# Tags Definition
>>> tag_engine = CVTEngine()
>>> tag_engine.set_tag('Counter', 'Adim.', 'int', 'Counter variable', 0, 30)

# Tag Definition on DB
interval = 0.5
app.set_dbtags(['Counter'], interval)

Postgres Database (Production Mode)

Usage

db_user = 'db_user'
db_password = 'db_password'
db_host = '127.0.0.1'
db_port = '5432'
db_name = 'db_name'
db_drop_table = False

DATABASE = {
    'user': db_user,
    'password': db_password,
    'host': db_host,
    'port': db_port,
    'name': db_name
    }

app.set_db(dbtype=POSTGRESQL, drop_table=db_drop_table, **DATABASE)

Binding App with Database

@app.define_machine(name='CounterSimulator', interval=interval, mode="async")
class CounterSimulator(PyHadesStateMachine):

    # states
    start  = State('starting', initial=True)
    run  = State('running')
    reset = State('resetting')

    # transitions
    start_to_run = start.to(run)
    run_to_reset = run.to(reset)
    reset_to_start = reset.to(start)

    # parameters
    max_counter = IntegerType()
    counter = TagBinding('Counter')
    counter_write = TagBinding('Counter', direction='write')

    def __init__(self, name):

        super().__init__(name)

    def while_start(self):
        self.max_counter = tag_engine.get_max_value('Counter')
        self.start_to_run()

    def while_run(self):

        self.counter_write = self.counter + 1

        if self.counter >= self.max_counter:

            self.run_to_reset()

        print(f"Counter: {self.counter}")

    def while_reset(self):

        self.counter_write = 0
        self.reset_to_start()

if __name__=='__main__':

    app.run()