Connection

Async database connection that assembles t-string queries and parses results.

Use as an async context manager to start a fassung.connection.Transaction:

async with connection as txn:
    await txn.execute(t"...")

`add_listener(channel, payload_type, callback)` `async`

Subscribe to PostgreSQL LISTEN/NOTIFY notifications on channel.

The raw notification payload is parsed into payload_type before being passed to callback.

Parameters:

Name	Type	Description	Default
`channel`	`str`	The notification channel name.	required
`payload_type`	`type[T]`	The type to parse the payload into.	required
`callback`	`Listener[T]`	The listener to invoke on each notification.	required

Create a cursor factory for iterating over query results.

Parameters:

Name	Type	Description	Default
`type_`	`type[T]`	The row type to parse each result into.	required
`query`	`Template`	A t-string template containing the SQL query.	required
`prefetch`	`int \| None`	Number of rows to prefetch.	`None`
`timeout`	`float \| None`	Optional query timeout in seconds.	`None`

Execute a SQL command and return its status string.

Parameters:

Name	Type	Description	Default
`query`	`Template`	A t-string template containing the SQL to execute.	required
`timeout`	`float \| None`	Optional query timeout in seconds.	`None`

Execute a query and return all resulting rows as a typed list.

Parameters:

Name	Type	Description	Default
`type_`	`type[T]`	The row type to parse each result into.	required
`query`	`Template`	A t-string template containing the SQL query.	required
`timeout`	`float \| None`	Optional query timeout in seconds.	`None`

Execute a query and return the first row, or None if empty.

Parameters:

Name	Type	Description	Default
`type_`	`type[T]`	The row type to parse the result into.	required
`query`	`Template`	A t-string template containing the SQL query.	required
`timeout`	`float \| None`	Optional query timeout in seconds.	`None`

Execute a query and return a single scalar value.

Parameters:

Name	Type	Description	Default
`type_`	`type[T]`	The expected type of the returned value.	required
`query`	`Template`	A t-string template containing the SQL query.	required
`column`	`int`	Zero-based column index to extract.	`0`
`timeout`	`float \| None`	Optional query timeout in seconds.	`None`

Unsubscribe a previously registered listener from channel.

Parameters:

Name	Type	Description	Default
`channel`	`str`	The notification channel name.	required
`callback`	`Listener[T]`	The listener to remove.	required