rows - row factory implementations #

The module exposes a few generic RowFactory implementation, which can be used to retrieve data from the database in more complex structures than the basic tuples.

Check out Row factories for information about how to use these objects.

psycopg.rows. tuple_row ( cursor ) #

Row factory to represent rows as simple tuples.

This is the default factory, used when ~psycopg.Connection.connect() or ~psycopg.Connection.cursor() are called without a !row_factory parameter.

Return type :

RowMaker [ Tuple [ Any , ... ]]

psycopg.rows. dict_row ( cursor ) #

Row factory to represent rows as dictionaries.

The dictionary keys are taken from the column names of the returned columns.

Return type :

RowMaker [ Dict [ str , Any ]]

psycopg.rows. namedtuple_row ( cursor ) #

Row factory to represent rows as ~collections.namedtuple .

The field names are taken from the column names of the returned columns, with some mangling to deal with invalid names.

Return type :

RowMaker [ NamedTuple ]

psycopg.rows. class_row ( cls ) #

Generate a row factory to represent rows as instances of the class !cls .

The class must support every output column name as a keyword parameter.

Parameters :

cls ( Type [ TypeVar ( T , covariant=True)]) - The class to return for each row. It must support the fields returned by the query as keyword arguments.

Return type :

!Callable[[Cursor], RowMaker [~T]]

This is not a row factory, but rather a factory of row factories. Specifying !row_factory=class_row(MyClass) will create connections and cursors returning !MyClass objects on fetch.

Example:

from dataclasses import dataclass
import psycopg
from psycopg.rows import class_row

@dataclass
class Person:
    first_name: str
    last_name: str
    age: int = None

conn = psycopg.connect()
cur = conn.cursor(row_factory=class_row(Person))

cur.execute("select 'John' as first_name, 'Smith' as last_name").fetchone()
# Person(first_name='John', last_name='Smith', age=None)

psycopg.rows. args_row ( func ) #

Generate a row factory calling !func with positional parameters for every row.

Parameters :

func ( Callable [ ... , TypeVar ( T , covariant=True)]) - The function to call for each row. It must support the fields returned by the query as positional arguments.

Return type :

BaseRowFactory [ TypeVar ( T , covariant=True)]

psycopg.rows. kwargs_row ( func ) #

Generate a row factory calling !func with keyword parameters for every row.

Parameters :

func ( Callable [ ... , TypeVar ( T , covariant=True)]) - The function to call for each row. It must support the fields returned by the query as keyword arguments.

Return type :

BaseRowFactory [ TypeVar ( T , covariant=True)]