DBIish - a simple database interface for Raku
use v6;
use DBIish;
my $dbh = DBIish.connect("SQLite", :database<example-db.sqlite3>);
$dbh.execute(q:to/STATEMENT/);
DROP TABLE IF EXISTS nom
STATEMENT
$dbh.execute(q:to/STATEMENT/);
CREATE TABLE nom (
name varchar(4),
description varchar(30),
quantity int,
price numeric(5,2)
)
STATEMENT
$dbh.execute(q:to/STATEMENT/);
INSERT INTO nom (name, description, quantity, price)
VALUES ( 'BUBH', 'Hot beef burrito', 1, 4.95 )
STATEMENT
my $sth = $dbh.prepare(q:to/STATEMENT/);
INSERT INTO nom (name, description, quantity, price)
VALUES ( ?, ?, ?, ? )
STATEMENT
$sth.execute('TAFM', 'Mild fish taco', 1, 4.85);
$sth.execute('BEOM', 'Medium size orange juice', 2, 1.20);
# For one-off execution
$sth = $dbh.execute(q:to/STATEMENT/);
SELECT name, description, quantity, price, quantity*price AS amount
FROM nom
STATEMENT
say $sth.rows; # 3
for $sth.allrows() -> $row {
say $row[0]; # BUBH�TAFM�BEOM
}
$sth.dispose;
# For efficient multiple execution
$sth = $dbh.prepare('SELECT description FROM nom WHERE name = ?');
for <TAFM BEOM> -> $name {
for $sth.execute($name).allrows(:array-of-hash) -> $row {
say $row<description>;
}
}
$dbh.dispose;
The DBIish project provides a simple database interface for Raku.
It's not a port of the Perl 5 DBI and does not intend to become one. It is, however, a simple and useful database interface for Raku that works now. It looks like a DBI, and it talks like a DBI (although it only offers a subset of the functionality).
You obtain a DataBaseHandler
by calling the static DBIish.connect
method, passing as the only positional argument the driver name followed by any required named arguments.
Those named arguments are driver specific, but commonly required ones are: database
, user
and password
.
For the different syntactic forms of named arguments see the language documentation.
For example, for connect to a database 'hierarchy' on PostgreSQL, with the user in $user
and using the function get-secret
to obtain you password, you can:
my $dbh = DBIish.connect('Pg', :database<hierarchy>, :$user, password => get-secret());
See ahead more examples.
To disconnect from a database and free the allocated resources you should call the dispose
method:
$dbh.dispose;
For a single execution of a query you may use execute directly. This starts the query within the database and returns a StatementHandle
which will be used for [Retrieving Data](#retrieving-data).
$dbh.execute(q:to/SQL/);
CREATE TABLE tab (
id serial PRIMARY KEY
col text
);
SQL
Errors occurring within the database for an SQL statement will typically throw an exception within Raku. The level of detail within the exception object depends on the database driver.
$dbh.execute('CREATE TABLE failtab ( id );');
CATCH {
when X::DBDish::DBError {
say .message;
}
}
In order to build a query dynamically without risk of SQL injection you need to use parameter binding. The ?
will be replaced by an escaped copy of the parameter provided after the query.
my $value-id = 19;
$dbh.execute('INSERT INTO tab (id) VALUES (?)', $value-id);
my $value-text = q{Complex text ' value " with quotes};
$dbh.execute('INSERT INTO tab (id, col) VALUES (?, ?)', $value-id, $value-text);
# Undefined or Nil values will be converted to NULL by parameter binding.
my $value-nil;
$dbh.execute('INSERT INTO tab (id, col) VALUES (?, ?), $value-id, $value-nil);
Parameter binding should be used where-ever possible, even if the number of parameters is dynamic. In this case the number of elements for IN is dynamic. The number of ?
's is scaled to fit the list of items, and the list is provided to execute as individual items.
my @value-list = 1 .. 6;
my $parameter-bind-marks = @value-list.map({'?'}).join(',') # ?,?,?,?,?,?
my $query = 'SELECT id FROM tab WHERE id IN (%s)'.sprintf($parameter-bind-marks);
$dbh.execute($query, |@value-list);
All database drivers support basic Raku types like Int, Rat, Str, and Buf; some databases may support additional complex types such as an Array of Str or Array of Int which may simplify the above example significantly. Please see database specific documentation for additional type support.
Execute performs a couple of steps on the client side, and often the database side as well, which may be cached if a query is going to be executed several times. For simple queries, prepare() may increase performance by up to 50%
This is an inefficient example of running a query multiple times:
for 1 .. 100 -> $id {
$dbh.execute('INSERT INTO tab (id) VALUES (?)', $id);
}
This example is more efficient as it uses prepare to decrease overhead on the client side; often on the server-side too as the database may only need to parse the SQL once.
my $sth = $dbh.prepare('INSERT INTO tab (id) VALUES (?)');
for 1 .. 100 -> $id {
$sth.execute($id);
}
DBIish provides the row
and allrows
methods to fetch values from a StatementHandle
object returned by execute. These functions provide you typed values; for example an int4 field in the database will be provided as an Int scalar in Raku.
row
take the hash
adverb if you want to have the values in a Hash form instead of a plain Array
Example:
my $sth = $dbh.execute('SELECT id, col FROM tab WHERE id = ?', $value-id);
my @values = $sth.row();
my %values = $sth.row(:hash);
allrows
lazily returns all the rows as a list of arrays. If you want to fetch the values in a hash form, use one of the two adverbs array-of-hash
or hash-of-array
Example:
my $sth = $dbh.execute('SELECT id, col FROM tab');
my @data = $sth.allrows(); # [[1, 'val1'], [3, 'val2']]
my @data = $sth.allrows(:array-of-hash); # [ ( id => 1, col => 'val1'), ( id => 3, col => 'val2') ]
my %data = $sth.allrows(:hash-of-array); # id => [1, 3], col => ['val1', 'val2']
for $sth.allrows(:array-of-hash) -> $row {
say $row<id>; # 1�3
}
# Or as a shorter example:
for $dbh.execute('SELECT id, col FROM tab').allrows(:array-of-hash) -> $row {
say $row<id> # 1�3
}
After you have fetched all data using the statement handle, you can free its memory immediately using dispose
.
$sth.dispose;
server-version
returns a Version
object for the version of the server you are connected to. Not all drivers support this function (some may not connect to a server at all) so it's best to wrap in a can
.
my Version $version = $dbh.server-version() if $dbh.can('server-version');
All exceptions for a query result are thrown as or inherit X::DBDish::DBError
. Additional functionality may be provided by the database driver.
driver-name
-
Database Driver name for the connection
native-message
-
Unmodified message received from the database server.
code
-
Int return code from the local client library for the call; typically -1. This is not an SQL state.
why
-
A Str indicating why the exception was thrown. Typically 'Error'.
message
-
Human friendly and more informative version of the database message.
is-temporary
-
A Boolean flag which when true indicates that the transaction may succeed if retried. Connectivity issues, serialization issues and other temporary items may set this as True.
In general you should use the ?
parameter for substitution whenever possible. The database driver will ensure values are properly escaped prior to insertion into the database. However, if you need to create a query string by hand then you can use quote
to help prevent an SQL injection attack from being successful.
Using parameter substitution is preferred:
my $val = 'literal';
$dbh.execute('INSERT INTO tab VALUES (?)', $val);
However, if you must build the query directly you can:
my $val = 'literal';
my $query = 'INSERT INTO tab VALUES (%s)'.sprintf( $dbh.quote($val) );
$dbh.execute($query);
To build a query with a dynamic identifier:
# Notice that C<?> is still used for the value being inserted; it is still recommended where possible.
my $id = 'table';
my $val = 'literal';
my $query = 'INSERT INTO %s VALUES (?)'.sprintf( $dbh.quote($id, :as-id) );
$dbh.execute($query, $val);
$ zef install DBIish
Some DBDish drivers install together with DBIish.pm6 and are maintained as a single project.
Search the Raku ecosystem for additional DBDish drivers such as ODBC.
Currently the following backends are included:
Supports basic CRUD operations and prepared statements with placeholders
my $dbh = DBIish.connect('Pg', :host<db01.yourdomain.com>, :port(5432),
:database<blerg>, :user<myuser>, password => get-secret());
Pg supports the following named arguments: host
, hostaddr
, port
, database
(or its alias dbname
), user
, password
, connect-timeout
, client-encoding
, options
, application-name
, keepalives
, keepalives-idle
, keepalives-interval
, sslmode
, requiressl
, sslcert
, sslkey
, sslrootcert
, sslcrl
, requirepeer
, krbsrvname
, gsslib
, and service
.
See your PostgreSQL documentation for details.
In addition to the ?
style of parameter substitution supported by all drivers, PostgreSQL also supports numbered parameter. The advantage is that a numbered parameter may be reused
$dbh.execute('INSERT INTO tab VALUES ($1, $2, $2 - $1)', $var1, $var2);
This is equivalent to the below statement except the subtraction operation is performed by PostgreSQL:
$dbh.execute('INSERT INTO tab VALUES (?, ?, ?)', $var1, $var2, $var2 - $var1);
Pg arrays are supported for both writing via execute and retrieval via row/allrows
. You will get the properly typed array according to the field type.
Passing an array to execute
is now implemented. But you can also use the pg-array-str
method on your Pg StatementHandle to convert an Array to a string Pg can understand:
# Insert an array via an execute statement
my $sth = $dbh.execute('INSERT INTO tab (array_column) VALUES ($1);', @data);
# Prepare an insertion of an array field
my $sth = $dbh.prepare('INSERT INTO tab (array_column) VALUES ($1);');
$sth.execute(@data1); # or $sth.execute($sth.pg-array-str(@data1));
$sth.execute(@data2);
# Retrieve the array values back again.
for $dbh.execute('SELECT array_column FROM tab').allrows() -> $row {
my @array-column = $row[0];
}
# Check if "value" is in the dataset. This is similar to an IN statement.
my $sth = $dbh.prepare('SELECT * FROM tab WHERE value = ANY($1)');
$sth.execute(@data);
# If a datatype is needed you can cast the placeholder with the PostgreSQL datatype.
my $sth = $dbh.prepare('SELECT * FROM tab WHERE value = ANY($1::_cidr)');
$sth.execute(['127.0.0.1', '10.0.0.1']);
Consume available input from the server, buffering the read data if there is any. This is only necessary if you are planning on calling pg-notifies
without having requested input by other means (such as an execute
.)
$ret = $dbh.pg-notifies;
Looks for any asynchronous notifications received and returns a pg-notify object that looks like this
class pg-notify {
has Str $.relname; # Channel Name
has int32 $.be_pid; # Backend pid
has Str $.extra; # Payload
}
or nothing if there are no pending notifications.
In order to receive the notifications you should execute the PostgreSQL command "LISTEN" prior to calling pg-notifies
the first time; if you have not executed any other commands in the meantime you will also need to execute pg-consume-input
first.
For example:
$dbh.execute("LISTEN foo");
loop {
$dbh.pg-consume-input
if $dbh.pg-notifies -> $not {
say $not;
}
}
The payload is optional and will always be an empty string for PostgreSQL servers less than version 9.0.
Test to see if the connection is still considered live.
$dbh.ping
Exceptions for a query result are thrown as X::DBDish::DBError::Pg
objects (inherits X::DBDish::DBError
) and have the following additional attributes (described with a PG_DIAG_*
source name) as provided by the PostgreSQL client library libpq:
message
-
PG_DIAG_MESSAGE_PRIMARY
- The primary human-readable error message (typically one line). Always present. message-detail
-
PG_DIAG_MESSAGE_DETAIL
- Detail: an optional secondary error message carrying more detail about the problem. Might run to multiple lines. message-hint
-
PG_DIAG_MESSAGE_HINT
- Hint: an optional suggestion what to do about the problem. This is intended to differ from detail in that it offers advice (potentially inappropriate) rather than hard facts. Might run to multiple lines. context
-
PG_DIAG_CONTEXT
- An indication of the context in which the error occurred. Presently this includes a call stack traceback of active procedural language functions and internally-generated queries. The trace is one entry per line, most recent first. type
-
PG_DIAG_SEVERITY_NONLOCALIZED
- The severity; the field contents are ERROR, FATAL, or PANIC (in an error message), or WARNING, NOTICE, DEBUG, INFO, or LOG (in a notice message). This is identical to the PG_DIAG_SEVERITY field except that the contents are never localized. This is present only in reports generated by PostgreSQL versions 9.6 and later. type-localized
-
PG_DIAG_SEVERITY
- The severity; the field contents are ERROR, FATAL, or PANIC (in an error message), or WARNING, NOTICE, DEBUG, INFO, or LOG (in a notice message), or a localized translation of one of these. Always present. sqlstate
-
PG_DIAG_SQLSTATE
- The SQLSTATE code for the error. The SQLSTATE code identifies the type of error that has occurred; it can be used by front-end applications to perform specific operations (such as error handling) in response to a particular database error. For a list of the possible SQLSTATE codes, see Appendix A. This field is not localizable, and is always present. statement
-
Statement provided to prepare() or execute()
statement-name
-
Statement Name provided to prepare() or created internally
statement-position
-
PG_DIAG_STATEMENT_POSITION
- A string containing a decimal integer indicating an error cursor position as an index into the original statement string. The first character has index 1, and positions are measured in characters not bytes. internal-position
-
PG_DIAG_INTERNAL_POSITION
- This is defined the same as thePG_DIAG_STATEMENT_POSITION
field, but it is used when the cursor position refers to an internally generated command rather than the one submitted by the client. ThePG_DIAG_INTERNAL_QUERY
field will always appear when this field appears. internal-query
-
PG_DIAG_INTERNAL_QUERY
- The text of a failed internally-generated command. This could be, for example, a SQL query issued by a PL/pgSQL function. dbname
-
Database Name from libpq
pg-db()
host
-
Host from libpq
pg-host()
user
-
User from libpq
pg-user()
port
-
Port from libpq
pg-port()
schema
-
PG_DIAG_SCHEMA_NAME
- If the error was associated with a specific database object, the name of the schema containing that object, if any. table
-
PG_DIAG_TABLE_NAME
- If the error was associated with a specific table, the name of the table. (Refer to the schema name field for the name of the table's schema.) column
-
PG_DIAG_COLUMN_NAME
- If the error was associated with a specific table column, the name of the column. (Refer to the schema and table name fields to identify the table.) datatype
-
PG_DIAG_DATATYPE_NAME
- If the error was associated with a specific data type, the name of the data type. (Refer to the schema name field for the name of the data type's schema.) constraint
-
PG_DIAG_CONSTRAINT_NAME
- If the error was associated with a specific constraint, the name of the constraint. Refer to fields listed above for the associated table or domain. (For this purpose, indexes are treated as constraints, even if they weren't created with constraint syntax.) source-file
-
PG_DIAG_SOURCE_FILE
- The file name of the source-code location where the error was reported. source-line
-
PG_DIAG_SOURCE_LINE
- The line number of the source-code location where the error was reported. source-function
-
PG_DIAG_SOURCE_FUNCTION
- The name of the source-code function reporting the error.
Please see the PostgreSQL documentation for additional information.
A special is-temporary()
method returns True if an immediate retry of the full transaction should be attempted:
It is set to true when the SQLState is any of the following codes:
- SQLState Class 08XXX
-
All connection exceptions (possible temporary network issues)
- SQLState 40001
-
serialization_failure - Two or more transactions conflicted in a manner which may succeed if executed later.
- SQLState 40P01
-
deadlock_detected - Two or more transactions had locking conflicts resulting in a deadlock and this transaction being rolled back.
- SQLState Class 57XXX
-
Operator Intervention (early/forced connection termination).
- SQLState 72000
-
snapshot_too_old - The transaction took too long to execute. It may succeed during a quieter period.
my Int $socket = $dbh.pg-socket;
Returns the file description number of the connection socket to the server.
Supports basic CRUD operations and prepared statements with placeholders
my $dbh = DBIish.connect('SQLite', :database<thefile>);
The :database
parameter can be an absolute file path as well (or even an IO::Path
object):
my $dbh = DBIish.connect('SQLite', database => '/path/to/sqlite.db' );
If the SQLite library was compiled to be threadsafe (which is usually the case), then it is possible to use SQLite from multiple threads. This can be introspected:
say DBIish.install-driver('SQLite').threadsafe;
SQLite does support using one connection object concurrently, however other databases may not; if portability is a concern, then only use a particular connection object from one thread at a time (and so have multiple connection objects).
When using a SQLite database concurrently (from multiple threads, or even multiple processes), operations may not be able to happen immediately due to the database being locked. DBIish sets a default timeout of 10000 miliseconds; this can be changed by passing the busy-timeout
option to connect
.
my $dbh = DBIish.connect('SQLite', :database<thefile>, :60000busy-timeout);
Passing a value less than or equal to zero will disable the timeout, resulting in any operation that cannot take place immediately producing a database locked error.
Supports basic CRUD operations and prepared statements with placeholders
my $dbh = DBIish.connect('mysql', :host<db02.yourdomain.com>, :port(3306),
:database<blerg>, :user<myuser>, :$password);
# Or via socket:
my $dbh = DBIish.connect('mysql', :socket<mysql.sock>,
:database<blerg>, :user<myuser>, :$password);
Since MariaDB uses the same wire protocol as MySQL, the `mysql` backend also works for MariaDB.
DBDish::mysql by default searchs for 'mysql' (libmysql.ddl) on Windows and 'mysqlclient' (libmysqlclient.so.xx where xx in 16..21) on POSIX systems.
Remember that Windows uses PATH
to locate the library. On POSIX, unversionized *.so
files installed by "dev" packages aren't needed nor used, you need the run-time versionized library.
On POSIX you can use the $DBIISH_MYSQL_LIB
environment variable to request another client library to be searched and loaded.
Example using the unadorned name:
DBIISH_MYSQL_LIB=mariadb rakudo t/25-mysql-common.t
Using the absolute path in uninstalled DBIish:
DBIISH_MYSQL_LIB=/lib64/libmariadb.so.3 rakudo -t lib t/25-mysql-common.t
With MariaBD-Embedded:
DBIISH_MYSQL_LIB=mariadbd rakudo -I lib t/01-basic.t
Returns the AUTO_INCREMENT value of the most recently inserted record.
my $sth = $dbh.execute( 'INSERT INTO tab (description) VALUES (?)', $description );
my $id = $sth.insert-id;
# or
my $id = $dbh.insert-id;
Supports basic CRUD operations and prepared statements with placeholders
my $dbh = DBIish.connect('Oracle', database => 'XE', :user<sysadm>, :password('secret'));
The DBIish::CommonTesting
module, now with over 100 tests, provides a common unit testing that allows a driver developer to test its driver capabilities and the minimum expected compatibility.
Set environment variable DBIISH_WRITE_TEST=YES
to run tests which may leave permanent state changes in the database.
These will be removed on June 2022.
- $sth.fetchrow()
-
deprecated in favour of $sth.row()
- $sth.fetchrow_hashref()
-
deprecated in favour of $sth.row(:hash)
- $sth.fetchall_hashref()
-
deprecated in favour of $sth.allrows(:hash-of-arrays)
- $sth.fetchall-hash()
-
deprecated in favour of $sth.allrows(:hash-of-arrays)
- $sth.fetchall-AoH()
-
deprecated in favour of $sth.allrows(:array-of-hash)
- $sth.fetchrow_array()
-
deprecated in favour of $sth.row()
- $sth.fetchrow_hashref()
-
deprecated in favour of $sth.row(:hash)
- $sth.fetchrow_arrayref()
-
deprecated in favour of $sth.row(:hash)
- $sth.fetch()
-
deprecated in favour of $sth.row()
- $sth.fetchall_arrayref()
-
deprecated in favour of $sth.allrows(:array-of-hash)
- $sth.mysql_insertid
-
deprecated in favour of $sth.insert-id
- $dbh.mysql_insertid
-
deprecated in favour of $dbh.insert-id
- $dbh.disconnect
-
deprecated in favour of $sth.dispose
- $dbh.install_driver
-
deprecated in favour of $sth.install-driver
- $dbh.selectrow_arrayref
-
deprecated in favor of $sth = $dbh.prepare.execute(); $sth.row
- $dbh.selectrow_hashref
-
deprecated in favor of $sth = $dbh.prepare.execute(); $sth.row(:hash)
- $dbh.selectall_arrayref
-
deprecated in favor of $sth = $dbh.prepare.execute(); $sth.allrows
- $dbh.selectall_hashref
-
deprecated in favor of $sth = $dbh.prepare.execute(); $sth.allrows(:array-of-hashes)
- $dbh.selectcol_arrayref
-
deprecated in favor of $sth = $dbh.prepare.execute(); $sth.allrows(:array-of-hashes)
- $dbh.quote-identity($str)
-
deprecated in favor of $dbh.quote($str, :as-id)
The Raku Pod in the doc:DBIish module and examples in the examples directory.
This README and the documention of the DBIish and the DBDish modules are in the Pod6 format. It can be extracted by running
rakudo --doc <filename>
Or, if Pod::To::HTML is installed,
rakudo --doc=html <filename>
Additional modules of interest may include:
- DBIish::Transaction
-
A wrapper for managing transactions, including automatic retry for temporary failures.
- DBIish::Pool
-
Connection reuse for DBIish to reduce loads on high-volume or heavily encrypted database sessions.
DBIish is based on Martin Berends' MiniDBI project, but unlike MiniDBI, DBDish aims to provide an interface that takes advantage of Raku idioms.
There is/was an intention to integrate with the DBDI project once it has sufficient functionality.
So, while it is indirectly inspired by Perl 5 DBI, there are also many differences.
Written by Moritz Lenz, based on the MiniDBI code by Martin Berends.
See the CREDITS file for a list of all contributors.
Copyright © 2009-2020, the DBIish contributors All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.