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https://github.com/leont/protocol-postgres

A asynchronous postgres client library for Raku
https://github.com/leont/protocol-postgres

Last synced: 24 days ago
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A asynchronous postgres client library for Raku

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Name

====



Protocol::Postgres - a sans-io postgresql client



Synopsis

========



```raku

use v6.d;

use Protocol::Postgres;



my $socket = await IO::Socket::Async.connect($host, $port);

my $client = Protocol::Postgres::Client.new;

$socket.Supply(:bin).act({ $client.incoming-data($^data) });

$client.outbound-data.act({ $socket.write($^data) });



await $client.startup($user, $database, $password);



my $resultset = await $client.query('SELECT * FROM foo WHERE id = $1', [ 42 ]);

react {

	whenever $resultset.hash-rows -> (:$name, :$description, :$id) {

		say "$name is $description";

	}

}

```



Description

===========



Protocol::Postgres is sans-io implementation of (the client side of) the postgresql protocol. It is typically used through the `Protocol::Postgres::Client` class.



Client

======



`Protocol::Postgres::Client` has the following methods



new(--> Protocol::Postgres::Client)

-----------------------------------



This creates a new postgres client. It supports one optional named argument:



  * TypeMap :$typemap = TypeMap::JSON



    This is the typemap that is used to translate between Raku's and Postgres' typesystem. The default mapping supports common built-in types such as strings, numbers, bools, dates, datetimes, blobs, arrays and hashes. Other options include `TypeMap::Native` if you want arrays to map to postgres' native arrays and `TypeMap::Minimal` if one wants all values to map to strings.



outgoing-data(--> Supply)

-------------------------



This returns a `Supply` of `Blob`s to be written to the server.



incoming-data(Blob --> Nil)

---------------------------



This consumes bytes received from the server.



startup($user, $database?, $password? --> Promise)

--------------------------------------------------



This starts the handshake to the server. `$database` may be left undefined, the server will use `$user` as database name. If a `$password` is defined, any of clearnext, md5 or SCRAM-SHA-256 based authentication is supported.



The resulting promise will finish when the connection is ready for queries.



query($query, @bind-values --> Promise)

---------------------------------------



This will issue a query with the given bind values, and return a promise to the result.



For fetching queries such as `SELECT` the result in the promise will be a `ResultSet` object, for manipulation (e.g. `INSERT`) and definition (e.g. `CREATE`) queries it will result a string describing the change (e.g. `DELETE 3`). For a `COPY FROM` query it will `Supply` with the data stream, and for `COPY TO` it will be a `Supplier`.



Both the input types and the output types will be typemapped between Raku types and Postgres types using the typemapper.



query-multiple($query --> Supply[ResultSet])

--------------------------------------------



This will issue a complex query that may contain multiple statements, but can not use bind values. It will return a `Supply` to the results of each query.



prepare($query, :@input-types --> Promise[PreparedStatement])

-------------------------------------------------------------



This prepares the query, and returns a Promise to the PreparedStatement object. `@input-types` can be used to pass on hints about the types you're passing in during `execute`.



method get-channel(Str $name --> Supply)

----------------------------------------



This returns the `Supply` for the given channel.



add-enum-type(Str $name, ::Enum --> Promise)

--------------------------------------------



This looks up the `oid` of postgres enum `$name`, and adds an appriopriate `Type` object to the typemap to convert it from/to `Enum`.



add-composite-type(Str $name, ::Composite, Bool :$positional --> Promise)

-------------------------------------------------------------------------



This looks up the `oid` of the postgres composite type <$name>, and maps it to `Composite`; if `$positional` is set it will use positional constructor arguments, otherwise named ones are used; it will use a heuristic by default.



add-custom-type(Str $name, ::Custom, &from-string?, &to-string?)

----------------------------------------------------------------



This adds a custom converter from postgres type `$name` from/to Raku type `Custom`. By default `&from-string` will do a coercion, and `&to-string` will do stringification.



startTls(--> Blob)

------------------



This will return the marker that should be written to the server to start upgrading the connection to use TLS. If the server responds with a single `S` byte the proposal is accepted and the client is expected to initiate the TLS handshake. If the server responds with an `N` it is rejected, and the connection proceeds in cleartext.



terminate(--> Nil)

------------------



This sends a message to the server to terminate the connection



disconnected(--> Promise)

-------------------------



This returns a `Promise` that must be be kept or broken to signal the connection is lost.



query-status(--> Protocol::Postgres::QueryStatus)

-------------------------------------------------



This returns the query status as of the last finished query as a `enum Protocol::Postgres::QueryStatus` value: `Idle` (No transaction is active), `Transaction` (A transaction is currently in progress) or `Error` (The current transaction has failed and needs to be rolled back).



process-id(--> Int)

-------------------



This returns the process id of the backend of this connection. This is useful for debugging purposes and for notifications.



get-parameter(Str $name --> Str)

--------------------------------



This returns various parameters, currently known parameters are: `server_version`, `server_encoding`, `client_encoding`, `application_name`, `default_transaction_read_only`, `in_hot_standby`, `is_superuser`, `session_authorization`, `DateStyle`, `IntervalStyle`, `TimeZone`, `integer_datetimes`, and `standard_conforming_strings`.



ResultSet

=========



A `Protocol::Postgres::ResultSet` represents the results of a query, if any.



columns(--> List)

-----------------



This returns the column names for this resultset.



rows(--> Supply[List])

----------------------



This returns a Supply of rows. Each row is a list of values.



hash-rows(--> Supply[Hash])

---------------------------



This returns a Supply of rows. Each row is a hash with the column names as keys and the row values as values.



object-rows(::Class, Bool :$positional --> Supply[Class])

---------------------------------------------------------



This returns a Supply of objects of class `Class`, each object is constructed form the row hash unless positional is true in which case it's constructed from the row list.



arrays

------



This returns a sequence of arrays of results from all rows. This may `await`.



array

-----



This returns a single array of results from one row. This may `await`.



value

-----



This returns a single value from a single row. This may `await`.



hashes

------



This returns a sequence of hashes of the results from all rows. This may `await`.



hash

----



This returns a single hash of the results from one rows. This may `await`.



objects(::Class, Bool :$positional)

-----------------------------------



This returns a sequence of objects based on all the rows. This may `await`.



object(:Class, Bool :$positional)

---------------------------------



This returns a single object based on a single row. This may `await`.



PreparedStatement

=================



A `Protocol::Postgres::PreparedStatement` represents a prepated statement. Its reason of existence is to call `execute` on it.



execute(@arguments --> Promise[ResultSet])

------------------------------------------



This runs the prepared statement, much like the `query` method would have done.



close()

-------



This closes the prepared statement.



columns()

---------



This returns the columns of the result once executed.



Notification

============



`Protocol::Postgres::Notification` has the following methods:



sender(--> Int)

---------------



This is the process-id of the sender



channel(--> Str)

----------------



This is the name of the channel that the notification was sent on



message(--> Str)

----------------



This is the message of the notification



Author

======



Leon Timmermans 



Copyright and License

=====================



Copyright 2022 Leon Timmermans



This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.