NAME¶
DBIx::Class::Storage::DBI - DBI storage handler
SYNOPSIS¶
my $schema = MySchema->connect('dbi:SQLite:my.db');
$schema->storage->debug(1);
my @stuff = $schema->storage->dbh_do(
sub {
my ($storage, $dbh, @args) = @_;
$dbh->do("DROP TABLE authors");
},
@column_list
);
$schema->resultset('Book')->search({
written_on => $schema->storage->datetime_parser->format_datetime(DateTime->now)
});
DESCRIPTION¶
This class represents the connection to an RDBMS via DBI. See
DBIx::Class::Storage for general information. This pod only documents
DBI-specific methods and behaviors.
METHODS¶
connect_info¶
This method is normally called by "connection" in DBIx::Class::Schema,
which encapsulates its argument list in an arrayref before passing them here.
The argument list may contain:
- •
- The same 4-element argument set one would normally pass to
"connect" in DBI, optionally followed by extra attributes
recognized by DBIx::Class:
$connect_info_args = [ $dsn, $user, $password, \%dbi_attributes?, \%extra_attributes? ];
- •
- A single code reference which returns a connected DBI database handle
optionally followed by extra attributes recognized by DBIx::Class:
$connect_info_args = [ sub { DBI->connect (...) }, \%extra_attributes? ];
- •
- A single hashref with all the attributes and the dsn/user/password mixed
together:
$connect_info_args = [{
dsn => $dsn,
user => $user,
password => $pass,
%dbi_attributes,
%extra_attributes,
}];
$connect_info_args = [{
dbh_maker => sub { DBI->connect (...) },
%dbi_attributes,
%extra_attributes,
}];
This is particularly useful for Catalyst based applications, allowing the
following config (Config::General style):
<Model::DB>
schema_class App::DB
<connect_info>
dsn dbi:mysql:database=test
user testuser
password TestPass
AutoCommit 1
</connect_info>
</Model::DB>
The "dsn"/"user"/"password" combination can be
substituted by the "dbh_maker" key whose value is a coderef that
returns a connected DBI database handle
Please note that the DBI docs recommend that you always explicitly set
"AutoCommit" to either
0 or
1. DBIx::Class further
recommends that it be set to
1, and that you perform transactions via
our "txn_do" in DBIx::Class::Schema method. DBIx::Class will set it
to
1 if you do not do explicitly set it to zero. This is the default
for most DBDs. See "DBIx::Class and AutoCommit" for details.
DBIx::Class specific connection attributes
In addition to the standard DBI connection attributes, DBIx::Class recognizes
the following connection options. These options can be mixed in with your
other DBI connection attributes, or placed in a separate hashref
("\%extra_attributes") as shown above.
Every time "connect_info" is invoked, any previous settings for these
options will be cleared before setting the new ones, regardless of whether any
options are specified in the new "connect_info".
- on_connect_do
- Specifies things to do immediately after connecting or re-connecting to
the database. Its value may contain:
- a scalar
- This contains one SQL statement to execute.
- an array reference
- This contains SQL statements to execute in order. Each element contains a
string or a code reference that returns a string.
- a code reference
- This contains some code to execute. Unlike code references within an array
reference, its return value is ignored.
- on_disconnect_do
- Takes arguments in the same form as "on_connect_do" and executes
them immediately before disconnecting from the database.
Note, this only runs if you explicitly call "disconnect" on the
storage object.
- on_connect_call
- A more generalized form of "on_connect_do" that calls the
specified "connect_call_METHOD" methods in your storage driver.
on_connect_do => 'select 1'
is equivalent to:
on_connect_call => [ [ do_sql => 'select 1' ] ]
Its values may contain:
- a scalar
- Will call the "connect_call_METHOD" method.
- a code reference
- Will execute "$code->($storage)"
- an array reference
- Each value can be a method name or code reference.
- an array of arrays
- For each array, the first item is taken to be the
"connect_call_" method name or code reference, and the rest are
parameters to it.
Some predefined storage methods you may use:
- do_sql
- Executes a SQL string or a code reference that returns a SQL string. This
is what "on_connect_do" and "on_disconnect_do" use.
It can take:
- a scalar
- Will execute the scalar as SQL.
- an arrayref
- Taken to be arguments to "do" in DBI, the SQL string optionally
followed by the attributes hashref and bind values.
- a code reference
- Will execute "$code->($storage)" and execute the return array
refs as above.
- datetime_setup
- Execute any statements necessary to initialize the database session to
return and accept datetime/timestamp values used with
DBIx::Class::InflateColumn::DateTime.
Only necessary for some databases, see your specific storage driver for
implementation details.
- on_disconnect_call
- Takes arguments in the same form as "on_connect_call" and
executes them immediately before disconnecting from the database.
Calls the "disconnect_call_METHOD" methods as opposed to the
"connect_call_METHOD" methods called by
"on_connect_call".
Note, this only runs if you explicitly call "disconnect" on the
storage object.
- disable_sth_caching
- If set to a true value, this option will disable the caching of statement
handles via "prepare_cached" in DBI.
- limit_dialect
- Sets a specific SQL::Abstract::Limit-style limit dialect, overriding the
default "sql_limit_dialect" setting of the storage (if any). For
a list of available limit dialects see
DBIx::Class::SQLMaker::LimitDialects.
- quote_names
- When true automatically sets "quote_char" and
"name_sep" to the characters appropriate for your particular
RDBMS. This option is preferred over specifying "quote_char"
directly.
- quote_char
- Specifies what characters to use to quote table and column names.
"quote_char" expects either a single character, in which case is
it is placed on either side of the table/column name, or an arrayref of
length 2 in which case the table/column name is placed between the
elements.
For example under MySQL you should use "quote_char => '`'", and
for SQL Server you should use "quote_char => [qw/[ ]/]".
- name_sep
- This parameter is only useful in conjunction with "quote_char",
and is used to specify the character that separates elements (schemas,
tables, columns) from each other. If unspecified it defaults to the most
commonly used ".".
- unsafe
- This Storage driver normally installs its own "HandleError",
sets "RaiseError" and "ShowErrorStatement" on, and
sets "PrintError" off on all database handles, including those
supplied by a coderef. It does this so that it can have consistent and
useful error behavior.
If you set this option to a true value, Storage will not do its usual
modifications to the database handle's attributes, and instead relies on
the settings in your connect_info DBI options (or the values you set in
your connection coderef, in the case that you are connecting via coderef).
Note that your custom settings can cause Storage to malfunction, especially
if you set a "HandleError" handler that suppresses exceptions
and/or disable "RaiseError".
- auto_savepoint
- If this option is true, DBIx::Class will use savepoints when nesting
transactions, making it possible to recover from failure in the inner
transaction without having to abort all outer transactions.
- cursor_class
- Use this argument to supply a cursor class other than the default
DBIx::Class::Storage::DBI::Cursor.
Some real-life examples of arguments to "connect_info" and
"connect" in DBIx::Class::Schema
# Simple SQLite connection
->connect_info([ 'dbi:SQLite:./foo.db' ]);
# Connect via subref
->connect_info([ sub { DBI->connect(...) } ]);
# Connect via subref in hashref
->connect_info([{
dbh_maker => sub { DBI->connect(...) },
on_connect_do => 'alter session ...',
}]);
# A bit more complicated
->connect_info(
[
'dbi:Pg:dbname=foo',
'postgres',
'my_pg_password',
{ AutoCommit => 1 },
{ quote_char => q{"} },
]
);
# Equivalent to the previous example
->connect_info(
[
'dbi:Pg:dbname=foo',
'postgres',
'my_pg_password',
{ AutoCommit => 1, quote_char => q{"}, name_sep => q{.} },
]
);
# Same, but with hashref as argument
# See parse_connect_info for explanation
->connect_info(
[{
dsn => 'dbi:Pg:dbname=foo',
user => 'postgres',
password => 'my_pg_password',
AutoCommit => 1,
quote_char => q{"},
name_sep => q{.},
}]
);
# Subref + DBIx::Class-specific connection options
->connect_info(
[
sub { DBI->connect(...) },
{
quote_char => q{`},
name_sep => q{@},
on_connect_do => ['SET search_path TO myschema,otherschema,public'],
disable_sth_caching => 1,
},
]
);
on_connect_do¶
This method is deprecated in favour of setting via "connect_info".
on_disconnect_do¶
This method is deprecated in favour of setting via "connect_info".
dbh_do¶
Arguments: ($subref | $method_name), @extra_coderef_args?
Execute the given $subref or $method_name using the new exception-based
connection management.
The first two arguments will be the storage object that "dbh_do" was
called on and a database handle to use. Any additional arguments will be
passed verbatim to the called subref as arguments 2 and onwards.
Using this (instead of $self->_dbh or $self->dbh) ensures correct
exception handling and reconnection (or failover in future subclasses).
Your subref should have no side-effects outside of the database, as there is the
potential for your subref to be partially double-executed if the database
connection was stale/dysfunctional.
Example:
my @stuff = $schema->storage->dbh_do(
sub {
my ($storage, $dbh, @cols) = @_;
my $cols = join(q{, }, @cols);
$dbh->selectrow_array("SELECT $cols FROM foo");
},
@column_list
);
disconnect¶
Our "disconnect" method also performs a rollback first if the database
is not in "AutoCommit" mode.
with_deferred_fk_checks¶
- Arguments: $coderef
- Return Value: The return value of $coderef
Storage specific method to run the code ref with FK checks deferred or in
MySQL's case disabled entirely.
connected¶
- Arguments: none
- Return Value: 1|0
Verifies that the current database handle is active and ready to execute an SQL
statement (e.g. the connection did not get stale, server is still answering,
etc.) This method is used internally by "dbh".
dbh¶
Returns a $dbh - a data base handle of class DBI. The returned handle is
guaranteed to be healthy by implicitly calling "connected", and if
necessary performing a reconnection before returning. Keep in mind that this
is very
expensive on some database engines. Consider using
"dbh_do" instead.
connect_call_datetime_setup¶
A no-op stub method, provided so that one can always safely supply the
connection option
on_connect_call => 'datetime_setup'
This way one does not need to know in advance whether the underlying storage
requires any sort of hand-holding when dealing with calendar data.
select¶
- Arguments: $ident, $select, $condition, $attrs
Handle a SQL select statement.
sql_limit_dialect¶
This is an accessor for the default SQL limit dialect used by a particular
storage driver. Can be overridden by supplying an explicit
"limit_dialect" to "connect" in DBIx::Class::Schema. For a
list of available limit dialects see DBIx::Class::SQLMaker::LimitDialects.
last_insert_id¶
Return the row id of the last insert.
_native_data_type¶
- Arguments: $type_name
This API is
EXPERIMENTAL, will almost definitely change in the future,
and currently only used by ::AutoCast and ::Sybase::ASE.
The default implementation returns "undef", implement in your Storage
driver if you need this functionality.
Should map types from other databases to the native RDBMS type, for example
"VARCHAR2" to "VARCHAR".
Types with modifiers should map to the underlying data type. For example,
"INTEGER AUTO_INCREMENT" should become "INTEGER".
Composite types should map to the container type, for example
"ENUM(foo,bar,baz)" becomes "ENUM".
sqlt_type¶
Returns the database driver name.
bind_attribute_by_data_type¶
Given a datatype from column info, returns a database specific bind attribute
for "$dbh->bind_param($val,$attribute)" or nothing if we will let
the database planner just handle it.
This method is always called after the driver has been determined and a DBI
connection has been established. Therefore you can refer to
"DBI::$constant" and/or "DBD::$driver::$constant"
directly, without worrying about loading the correct modules.
is_datatype_numeric¶
Given a datatype from column_info, returns a boolean value indicating if the
current RDBMS considers it a numeric value. This controls how
"set_column" in DBIx::Class::Row decides whether to mark the column
as dirty - when the datatype is deemed numeric a "!=" comparison
will be performed instead of the usual "eq".
create_ddl_dir¶
- Arguments: $schema, \@databases, $version, $directory, $preversion,
\%sqlt_args
Creates a SQL file based on the Schema, for each of the specified database
engines in "\@databases" in the given directory. (note: specify
SQL::Translator names, not DBI driver names).
Given a previous version number, this will also create a file containing the
ALTER TABLE statements to transform the previous schema into the current one.
Note that these statements may contain "DROP TABLE" or "DROP
COLUMN" statements that can potentially destroy data.
The file names are created using the "ddl_filename" method below,
please override this method in your schema if you would like a different file
name format. For the ALTER file, the same format is used, replacing $version
in the name with "$preversion-$version".
See "METHODS" in SQL::Translator for a list of values for
"\%sqlt_args". The most common value for this would be "{
add_drop_table => 1 }" to have the SQL produced include a "DROP
TABLE" statement for each table created. For quoting purposes supply
"quote_identifiers".
If no arguments are passed, then the following default values are assumed:
- databases - ['MySQL', 'SQLite', 'PostgreSQL']
- version - $schema->schema_version
- directory - './'
- preversion - <none>
By default, "\%sqlt_args" will have
{ add_drop_table => 1, ignore_constraint_names => 1, ignore_index_names => 1 }
merged with the hash passed in. To disable any of those features, pass in a
hashref like the following
{ ignore_constraint_names => 0, # ... other options }
WARNING: You are strongly advised to check all SQL files created, before
applying them.
deployment_statements¶
- Arguments: $schema, $type, $version, $directory, $sqlt_args
Returns the statements used by "deploy" in DBIx::Class::Storage and
"deploy" in DBIx::Class::Schema.
The SQL::Translator (not DBI) database driver name can be explicitly provided in
$type, otherwise the result of "sqlt_type" is used as default.
$directory is used to return statements from files in a previously created
"create_ddl_dir" directory and is optional. The filenames are
constructed from "ddl_filename" in DBIx::Class::Schema, the schema
name and the $version.
If no $directory is specified then the statements are constructed on the fly
using SQL::Translator and $version is ignored.
See "METHODS" in SQL::Translator for a list of values for $sqlt_args.
datetime_parser¶
Returns the datetime parser class
datetime_parser_type¶
Defines the datetime parser class - currently defaults to
DateTime::Format::MySQL
build_datetime_parser¶
See "datetime_parser"
is_replicating¶
A boolean that reports if a particular DBIx::Class::Storage::DBI is set to
replicate from a master database. Default is undef, which is the result
returned by databases that don't support replication.
lag_behind_master¶
Returns a number that represents a certain amount of lag behind a master db when
a given storage is replicating. The number is database dependent, but starts
at zero and increases with the amount of lag. Default in undef
relname_to_table_alias¶
- Arguments: $relname, $join_count
- Return Value: $alias
DBIx::Class uses DBIx::Class::Relationship names as table aliases in queries.
This hook is to allow specific DBIx::Class::Storage drivers to change the way
these aliases are named.
The default behavior is ""$relname_$join_count" if $join_count
> 1", otherwise "$relname".
USAGE NOTES¶
DBIx::Class and AutoCommit¶
DBIx::Class can do some wonderful magic with handling exceptions,
disconnections, and transactions when you use "AutoCommit => 1"
(the default) combined with txn_do for transaction support.
If you set "AutoCommit => 0" in your connect info, then you are
always in an assumed transaction between commits, and you're telling us you'd
like to manage that manually. A lot of the magic protections offered by this
module will go away. We can't protect you from exceptions due to database
disconnects because we don't know anything about how to restart your
transactions. You're on your own for handling all sorts of exceptional cases
if you choose the "AutoCommit => 0" path, just as you would be
with raw DBI.
FURTHER QUESTIONS?¶
Check the list of additional DBIC resources.
COPYRIGHT AND LICENSE¶
This module is free software copyright by the DBIx::Class (DBIC) authors. You
can redistribute it and/or modify it under the same terms as the DBIx::Class
library.