Message Types

This document contains autoclass definitions for all of the various message types used throughout the library. These are returned from all three layers of API, although some only at certain levels.

Base Classes

These classes are never returned directly, but are supertypes to other message classes.

class pg_purepy.messages.PostgresMessage

Bases: object

Base class for a PostgreSQL protocol message.

class pg_purepy.messages.QueryResultMessage

Bases: PostgresMessage, ABC

Superclass for query results.

State-related messages

These classes usually represent some form of internal state change.

class pg_purepy.messages.ParameterStatus(name, value)

Bases: PostgresMessage

Returned when a configuration parameter is changed, e.g. via SET.

class pg_purepy.messages.ErrorOrNoticeResponse(notice, recoverable, severity_localised, severity, code, message, hint=None, detail=None, position=None, internal_position=None, internal_query=None, where=None, schema_name=None, table_name=None, column_name=None, data_type_name=None, constraint_name=None)

Bases: PostgresMessage

Returned when an error or a notice message is produced from the server.

notice: bool

If this error is a notice, rather than a real error.

recoverable: bool

If this error is recoverable or not.

class pg_purepy.messages.ReadyForQuery(state)

Bases: PostgresMessage

Returned when the protocol machine is ready for the next query cycle.

state: ReadyForQueryState

The sub-state that the current connection is in.

class pg_purepy.messages.ReadyForQueryState(*values)

Bases: Enum

Enumeration of possible ReadyForQuery states.

IDLE = 73

The server is idle and not in any transaction.

IN_TRANSACTION = 84

The server is currently in a transaction, and new commands can be issued.

ERRORED_TRANSACTION = 69

The server is currently in a transaction that has errored, and no new commands can be issued.

Auth-related messages

These classes relate to the authentication loop.

class pg_purepy.messages.AuthenticationRequest(method, md5_salt=None, sasl_methods=NOTHING)

Bases: PostgresMessage

Returned when the PostgreSQL server requires authentication.

method: AuthenticationMethod

The authentication method required.

md5_salt: bytearray | None

When doing MD5 authentication, the salt to use.

sasl_methods: list[str]

When doing SASL authentication, the list of authentication methods.

class pg_purepy.messages.AuthenticationMethod(*values)

Bases: IntEnum

Enumeration of supported authentication methods.

CLEARTEXT = 3

The server wishes for us to send our password in clear text.

MD5 = 5

The server wishes for us to use MD5 hashing for our password.

SASL = 10

The server wishes for us to use SASL authentication.

class pg_purepy.messages.BackendKeyData(pid, secret_key)

Bases: PostgresMessage

Misc data used for cancellation.

pid: int

The int PID of this connection.

secret_key: int

The 64-bit int secret key data of this connection.

class pg_purepy.messages.AuthenticationCompleted

Bases: PostgresMessage

Returned when authentication is completed.

Query-related messages

These classes relate to parts of the query cycle.

Both simple and extended queries:

class pg_purepy.messages.ColumnDescription(name, table_oid, column_index, type_oid, column_length, type_modifier)

Bases: object

A description of a column.

name: str

The str name of this column.

table_oid: int | None

The optional int table OID of this column.

column_index: int | None

The optional int column index of this column.

type_oid: int

The :class`int` type OID of this column.

column_length: int

The :class`int` internal column length.

type_modifier: int

The int type modifier for this column.

final class pg_purepy.messages.RowDescription(columns)

Bases: QueryResultMessage, Sequence[ColumnDescription]

Describes the rows of a query.

columns: list[ColumnDescription]

The list of ColumnDescription instances that wraps the decoding info for each column returned in this row.

final class pg_purepy.messages.DataRow(description, data)

Bases: QueryResultMessage, Sequence[Any]

A singular data row. This contains a RowDescription and a list of converted data values.

description: RowDescription

The RowDescription that describes the data within this row.

data: list[Any]

A list of column values, in the same order as the description, that contains the actual converted data incoming from the server.

to_dict()

Converts this data row to a dict. If multiple columns have the same name, this may not end up the way you expect.

Return type:

dict[str, Any]

class pg_purepy.messages.CommandComplete(tag, row_count)

Bases: QueryResultMessage

Returned when a single query command is complete.

tag: str

The str command tag. Probably useless.

row_count: int | None

The int row count returned. This may be None if the command does not have a row count (e.g. SHOW or SET).

Extended queries only:

class pg_purepy.messages.ParseComplete(statement_name)

Bases: PostgresMessage

Returned when parsing a prepared statement completes.

class pg_purepy.messages.ParameterDescription(oids)

Bases: PostgresMessage

Returned when parsing a ParameterDescription message.

oids: list[int]

The list of int OIDs within this description.

class pg_purepy.messages.PreparedStatementInfo(name, parameter_oids, row_description)

Bases: PostgresMessage

Contains the state of a prepared statement. Returned for a RowDescription over a prepared statement.

name: str | None

The str name of the prepared statement.

parameter_oids: ParameterDescription

The ParameterDescription for the parameters for this prepared statement.

row_description: RowDescription | None

The RowDescription of the incoming row data of the prepared statement. This may be None if this query doesn’t return any data.

class pg_purepy.messages.BindComplete

Bases: PostgresMessage

Returned when a Bind message completes successfully.