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Marzin edited this page Aug 20, 2022 · 12 revisions

HOW TO USE?:

Find an example of minimalist use in the Helloworld.gd file. Other examples will be provided later.

You can also watch Mitch McCollum (finepointcgi) video tutorial here:

Tuto

PostgreSQLClient DOCUMENTATION:

Note: This documentation only deals with the postgreSQL Client version for godot 3.x. Documentation for 4.x is still in the works.

PROPERTIES:

Type Properties Default value
float PROTOCOL_VERSION const 3.0
Dictionary parameter_status reader alone {}

METHODS:

Type Method
Error connect_to_host(url: String, secure_connection_method: PostgreSQLClient.SecureConnectionMethod = SecureConnectionMethod.NONE, connect_timeout: int = 30)
Status get_status()
Error execute(sql: String)
void rollback(process_id: int, process_key: int, secure_connection_method: int = SecureConnectionMethod.NONE)
void close(clean_closure: bool = true)
void poll()

SIGNALS:

Signal
connection_closed(was_clean_close: bool)
connection_error()
authentication_error(error_object: Dictionnary)
connection_established()
data_received(error_object: Dictionary, transaction_status: PostgreSQLClient.TransactionStatus, datas: Array)

ENUMARATIONS:

enum SecureConnectionMethod

  • NONE = 0 --- Represent a connection that is not secure.
  • SSL = 1 --- Represents a connection secured by an overlay of the SSL/TLS protocol.
  • GSSAPI = 2 --- Represents a connection secured by an overlay of the GSSAPI protocol.

enum Status

  • STATUS_DISCONNECTED = 0 --- A status representing a PostgreSQLClient that is disconnected.
  • STATUS_CONNECTING = 1 --- A status representing a PostgreSQLClient that is connecting to a host.
  • STATUS_CONNECTED = 2 --- A status representing a PostgreSQLClient that is connected to a host.
  • STATUS_ERROR = 3 --- A status representing a PostgreSQLClient in error state.

NOTE: The Status enumeration may not be exposed in future versions.

enum DataTypePostgreSQL

  • BOOLEAN = 16 --- Postgresql data type of type boolean.
  • SMALLINT = 21 --- Postgresql data type of type smallint.
  • INTEGER = 23 --- Postgresql data type of type integer.
  • BIGINT = 20 --- Postgresql data type of type bigint.
  • REAL = 700 --- Postgresql data type of type real.
  • DOUBLE_PRECISION = 701 --- Postgresql data type of type double precision.
  • TEXT = 25 --- Postgresql data type of type text.
  • CHARACTER = 1042 --- Postgresql data type of type character alias char.
  • CHARACTER_VARYING = 3802 --- Postgresql data type of type character varying alias varchar.
  • JSON_ = 114 --- Postgresql data type of type json.
  • JSONB = 3802 --- Postgresql data type of type jsonb.
  • XML = 142 --- Postgresql data type of type xml.
  • BITEA = 17 --- Postgresql data type of type bitea.
  • CIDR = 650 --- Postgresql data type of type cidr.
  • INET = 869 --- Postgresql data type of type inet.
  • MACADDR = 829 --- Postgresql data type of type macaddr.
  • MACADDR8 = 774 --- Postgresql data type of type macaddr8.
  • BIT = 1560 --- Postgresql data type of type bit.
  • BIT_VARYING = 1562 --- Postgresql data type of type bit varying.
  • UUID = 2950 --- Postgresql data type of type uuid.
  • POINT = 600 --- Postgresql data type of type point.
  • BOX = 603 --- Postgresql data type of type box.
  • LSEG = 601 --- Postgresql data type of type lseg.
  • LINE = 628 --- Postgresql data type of type line.
  • CIRCLE = 718 --- Postgresql data type of type circle.
  • DATE = 1082 --- Postgresql data type of type date.
  • TIME = 1266 --- Postgresql data type of type time.

NOTE: Not all PostgreSQL data types are supported by PostgreSQLClient, but will be in a future release.

enum TransactionStatus

  • NOT_IN_A_TRANSACTION_BLOCK = 0 --- Represents one or more querys that is not in a transaction block.
  • IN_A_TRANSACTION_BLOCK = 1 --- Represents one or more querys that are in a transaction block.
  • IN_A_FAILED_TRANSACTION_BLOCK = 2 --- Represents one or more querys in a transaction block with a error state.

Property Descriptions

  • float PROTOCOL_VERSION const

Default value: 3.0

Version number (minor.major) of the PostgreSQL protocol used when connecting to the backend

  • Dictionary parameter_status reader alone

Default value: {}

A dictionary that contains various information about the execution state of the server. For security reasons the dictionary is always empty if the frontend is disconnected from the backend and updates once the connection is established.

Noted that the server is free to return whatever value it wants. Always remember to check the presence of the key before accessing the associated value.

Example of a typical value that a backend might return. Values may differ depending on the backend:

{"DateStyle":"ISO, DMY", "IntervalStyle":"postgres", "TimeZone":"Europe/Paris", "application_name":"", "client_encoding":"UTF8", "integer_datetimes":"on", "is_superuser":"off", "server_encoding":"UTF8", "server_version":"12.7 (Ubuntu 12.7-0ubuntu0.20.04.1)", "session_authorization":"samuel", "standard_conforming_strings":"on"}

Method Descriptions

  • Error connect_to_host(url: String, secure_connection_method: int = SecureConnectionMethod.NONE, connect_timeout: int = 30)

Allows you to connect to a Postgresql backend at the specified url.

The url parameter is a PostgreSQL URL ideally in the form "postgresql://user:password@host:port/databasename". All other PostgreSQL URL syntaxes specified in this page [https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING] are not yet fully supported.

Noted that the default port for PostgreSQL is 5432.

The secure_connection_method parameter specifies the secure connection method of the frontend that it will try to establish with the backend. If the server is unfavorable, the connection will fail. Most of the time, all PostgreSQL backends are good at establishing an SSL / TLS connection. Old servers can be an exception.

The connect_timeout parameter specifies the maximum duration of the connection process. If the backend does not respond during this time, the connection will be considered to have failed.

  • Error execute(sql: String)

Allows to send an SQL string to the backend that should run. The sql parameter can contain one or more valid SQL statements.

  • Status get_status()

Returns the status of the connection (see the Status enumeration). Note that you should be able to use PostgreSQLCient without using it. The method may no longer be exposed in the future version.

  • void rollback(process_id : int, process_key : int, secure_connection_method: int = SecureConnectionMethod.NONE)

Do not use because it is too unstable, will be subject to modification in future versions.

  • void close(clean_closure: bool = true)

Allows you to close the connection with the backend. If clean_closure is true, the frontend will notify the backend that it requests to close the connection. If false, the frontend forcibly closes the connection without notifying the backend (not recommended except in exceptional cases).

Has no effect if the frontend is not already connected to the backend.

  • void poll()

Poll the connection to check for incoming messages. Ideally, it should be called before PostgreSQLClient.execute() for it to work properly and called frequently in a loop.

Signal Descriptions

  • connection_closed(was_clean_close: bool)

Fires when the connection to the backend closes. was_clean_close is true if the connection was closed correctly otherwise false.

  • connection_error()

Do not listen to this signal, does not work. will be subject to change see removed in future versions.

authentication_error(error_object: Dictionnary)

Triggered when the authentication process failed during contact with the target backend. The error_object parameter is a dictionary that contains various information during the nature of the error.

  • connection_established()

Trigger when the connection between the frontend and the backend is established. This is usually a good time to start making requests to the backend with execute ().

  • data_received(error_object: Dictionary, transaction_status: PostgreSQLClient.TransactionStatus, datas: Array)

Emitted when data is sent by the backend, usually after using the execute() method. It is also possible for the backend to send data which is not expressly requested by the frontend command flow so you should handle unsolicited messages to avoid any issues.

The error_object parameter is a Dictionary which contains various information on the execution errors of the last requests made on the backend (usually after using the execute() method). If the dictionary is empty, it means that the backend did not detect any error in the query.

The datas parameter is a Array of PostgreSQLQueryResult. There are as many PostgreSQLQueryResult elements in the array as there are SQL statements in sql (except in exceptional cases).

DOCUMENTATION PostgreSQLQueryResult:

Descriptions

The PostgreSQLQueryResult class is a subclass of PostgreSQLClient which is not intended to be created manually. It represents the result of an SQL query and provides an information and method report to use the result of the query. It is usually returned by the PostgreSQLClient.execute() method in an array of PostgreSQLQueryResult.

PROPERTIES:

Type Properties Default value
int number_of_fields_in_a_row reader alone 0
Array row_description reader alone []
Array data_row reader alone []
String command_tag reader alone ""
Dictionary notice reader alone {}

METHODS:

Type Method
Array get_field_values(field_name: String)
PostgreSQLClient.DataTypePostgreSQL field_data_type(field_name: String)

Property Descriptions

int number_of_fields_in_a_row const

Default value: 0

Specifies the number of fields in a row (can be zero).

Array row_description const

Default value: []

An array that contains dictionaries. these dictionaries represent the description of the rows where the query was executed. The number of dictionary depends on the number of fields resulting from the result of the query which was executed.

Each dictionary is structured like this:

{
	"field_name": field_name,
	"table_object_id": table_object_id,
	"column_index": column_index,
	"type_object_id": type_object_id,
	"data_type_size": data_type_size,
	"type_modifier": type_modifier,
	"format_code": format_code
}
  • Where the field_name value is a String that represents the name of the field.
  • Where the value table object_id is an int which represents the identifier of the table object whether the field can be identified as a column from a specific table; otherwise 0.
  • Where the column_index value is an int which represents the attribute number of the column if the field can be identified as a column from a specific table; otherwise zero.
  • Where the type_object_id value is an PostgreSQLClient.DataTypePostgreSQL which represents the object ID of the data type of the field.
  • Where the data_type_size value is an int which represents the size of the data type. Note: that negative values indicate variable width types.
  • Where the type_modifier value is an int which represents the type modifier. Note: The meaning of the modifier is type specific.
  • Where the format_code value is an int which represents the format code used for the field. Currently will be 0 (text) or 1 (binary). In a RowDescription returned by the instruction variant of Describe, the format code is not yet known and will always be zero. This value is low-level PostgreSQL protocol information that is not useful in most cases. You can ignore this value.

Array data_row const

Default value: []

An Array that contains sub-arrays. these sub-arrays represent for most of the queries the rows of the table where the query was executed. The number of sub-tables depends on the query that has been made. These sub-arrays contain as many elements as number_of_fields_in_a_row. These elements are native GDscript types that represent the data resulting from the query.

Example return value:

[[1, "Hello my id is 1"], [2, "Hello my id is 2"], [3, "Hello my id is 3"]]

There are 3 rows. Each row contains the value of 2 fields: The row identifier and a character string.

Table of type PostgreSQL equivalent to Godot

Types postgres Type Godot
null null
smallint, integer, bigint int
real, double precision float
text, character alias char, character varying alias varchar, json, jsonb, xml, cidr, inet, macaddr, macaddr8, bit, bit varying, uuid, date, time String
bitea PoolByteArray
point Vector2
box Rect2
lseg PoolVector2Array
line, circle Vector3

Note:

  • Not all PostgreSQL types are supported yet.
  • I may later change the date and time type to Dictionary, but I'm not sure...

String command_tag const

Default value: ""

This is usually a single word that identifies which SQL command was completed.

Dictionary notice const

Default value: {}

Represents various information about the execution status of the query notified by the backend. Can be empty.

Method Descriptions

Array get_field_values(field_name: String)

Returns all the values of a field. field_name is the name of the field on which we get the values. Can be empty if the field name is unknown. The field_name parameter is case sensitive.

PostgreSQLClient.DataTypePostgreSQL field_data_type(field_name: String)

Returns the object ID of the data type of the field. field_name is the name of the field whose type we get. Can return -1 if the field name is unknown. The field_name parameter is case sensitive.

Contacts:

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