NAME

DBIx::Interpolate - Interpolate Perl variables into SQL with DBI

STATUS

This module is not being actively maintained, although there is a fork with further updates. See the "Fork" section in SQL::Interp docs for details: http://search.cpan.org/perldoc?SQL::Interp#Fork.

SYNOPSIS

use DBI;
use DBIx::Interpolate qw(:all);

my $dbx = DBIx::Interpolate->new($dbh);  

my $rv = $dbx->do_i('INSERT INTO table', \%item);
my $rv = $dbx->do_i('UPDATE table SET',  \%item, 'WHERE item_id <> ', \2);
my $rv = $dbx->do_i('DELETE FROM table WHERE item_id = ', \2);

my $LoH = $dbx->selectall_arrayref_i('
      SELECT * FROM table WHERE x = ', \$s, 'AND y IN', \@v
      ,attr(Slice=>{}));

DESCRIPTION

DBIx::Interpolate does nothing more than bring SQL::Interpolate and DBI together (please read the documentation on those two modules for background). The DBIx::Interpolate interface adds some methods to the DBI interface with the "_i" suffix, indicating that interpolatation is performed automatically in these cases.

Helper Functions you may need

`attr`

$attrobj = attr(%attr);

Creates and returns an DBIx::Interpolate::Attr macro object, which if processed by dbi_interp() will cause dbi_interp() to add the provided key-value pair to the $attr hashref used by DBI methods.

my ($sql, $attr, @bind) = my @params =
  dbi_interp "SELECT a, b FROM mytable", attr(Columns=>[1,2]);
$dbh->selectcol_arrayref(@params);

`key_field`

$keyobj = key_field($key_field);

Creates and returns an DBIx::Interpolate::Key macro object, which if processed by dbi_interp() will cause dbi_interp() to return an extra $key_field value in the result so that the result is suitable for passing into $dbh->fetchrow_hashref and related methods.

my ($sql, $key, $attr, @bind) =
my @params = dbi_interp "SELECT * FROM mytable", key_field('itemid');
$dbh->selectall_hashref(@params);

Database object (DBX) methods

An object of type DBIx::Interpolate represents (and wraps) a database handle. Most of its methods are wrappers around corresponding DBI methods.

new (static method)

my $dbx = DBX::Interpolate->new($db, %params);

Creates a new object, creating or attaching a DBI handle.

$db is either a DBI database handle or an ARRAYREF containing parameters that will be passed to DBI::connect, e.g. [$data_source, $username, $auth, \%attr]. This parameter may be omitted.

Any additional %params are passed onto SQL::Interpolate::new.

connect (static method)

$dbx = DBIx::Interpolate->connect($data_source, $username, $auth, \%attr);

Connects to a database.

This is identical to DBI::connect except that it returns at DBIx::Interpolate object. An alternate way to connect or attach an existing DBI handle is via the new method.

dbh

$dbh = $dbx->dbh();

Returns the underlying DBI handle $dbh. The is useful if you need to pass the DBI handle to code that does not use SQL::Interpolate.

$dbx->dbh()->selectall_arrayref(
    "SELECT * FROM mytable WHERE x = ?", undef, $x);

stx

$stx = $dbx->stx();

Returns the underlying statement handle set $stx. (These are discussed later.) Each DBIx::Interpolate object contains one statement handle set for use on non-prepared database calls (e.g. selectall_.*() methods).

$dbx->stx()->max_sths(10);

do_i

selectall_arrayref_i

selectall_hashref_i

selectcol_arrayref_i

selectrow_array_i

selectrow_arrayref_i

selectrow_hashref_i

These methods are identical to those in DBI except interpolation is performed via SQL::Interpolate

prepare

$stx = $dbx->prepare();

Creates a new statement handle set ($stx of type SQL::Interpolate::STX) associated with $dbx. There are no parameters.

A statement handle set (stx) is an abstraction of a statement handle and represents an entire set of statement handles for a given class of SQL queries. This abstraction is used because a single interpolation list may interpolate into any number of SQL queries (depending on variable input), so multiple statement handles may need to be managed and cached. Typically, you do not need to call "prepare" directly because DBIx::Interpolate can transparently mangage a statement handle set (see $dbx->stx()->max_sths(10)).

Up to one statement handle in a set is considered active. Other operations performed on the statement handle set are passed to the active statement handle so that the statement handle set often looks and feels like a regular statement handle.

Statement handle set (STX) methods

These methods are for statement handle set objects.

new

$stx = SQL::Interpolate::STX->new($dbx);

Creates a new statement handle set. Typically this is not called directly but rather is invoked through prepare().

max_sths

$max_sths = $stx->max_sths(); # get
$stx->max_sths($max_sths);    # set

Gets or sets the maximum number of statement handles to cache in the statement handle set. The default and minimum value is 1.

sth

$sth = $stx->sth();

Gets the current active statement handle (e.g. the only that was just executed). Returns undef on none.

sths

$sths = $stx->sths();

Return a hashref of contained statement handles (map: $sql -> $sth).

execute

$rv = $stx->execute(@list);

Executes the query in the given interpolation list against a statement handle. If no statement matching statement handle exists, a new one is prepared. The used statement handle is made the active statement handle. Return on error behavior is similar to DBI's execute.

@list is an interpolation list (suitable for passing to dbi_interp()).

fetch...

$ary_ref = $stx->fetchrow_arrayref();

Various fetch.* methods analogous to those in DBIx::Interpolate are available. The fetch will be performed against the active statement handle in the set.

Internal functions

You normally don't need to care about this functions.

`dbi_interp`

($sql, $attr, @bind) = dbi_interp(@interp_list);
($sql, $key_field, $attr, @bind) = dbi_interp(@interp_list);

dbi_interp() is a thin wrapper around sql_interp(). It serves as an adapter that returns the exact parameter list expected by the DBI functions (including the \%attr value and sometimes the $key_field value).

In addition to the parameters accepted by SQL::Interpolate::sql_interp, @interp_list may contain the macros constructed by the attr() and key_field() functions discussed later. dbi_interp() will convert these DBI-specific macros as needed into additional return values expected by certain DBI methods. For example, DBI's selectall_hashref() requires an additional $key_field parameter:

$dbh->selectall_hashref($statement, $key_field, \%attr, @bind_values);

This is parameter is generated by adding the key_field() macro onto the interpolation list:

my ($sql, $key_field, $attr, @bind) = dbi_interp
    "SELECT * FROM mytable WHERE x=", \$x,
    key_field("y"), attr(myatt => 1)
# RESULT:
#   ($sql, $key_field, $attr, @bind) =
#       ("SELECT * FROM mytable WHERE x=?", 'y', {myatt=>1}, $x)

Typically, you need not call dbi_interp() directly since it is called internally by the DBI wrapper methods:

$dbx->selectall_hashref(
    "SELECT * FROM mytable WHERE x=", \$x,
    key_field("y"), attr(myatt => 1));
# largely equivalent to
#   $dbh->selectall_hashref(dbi_interp
#       "SELECT * FROM mytable WHERE x=", \$x,
#       key_field("y"), attr(myatt => 1));

`make_dbi_interp`

$dbi_interp = make_dbi_interp(@params);          # functional
$dbi_interp = $interp->make_dbi_interp(@params); # OO

This is similar to make_sql_interp() from SQL::Interpolate except that is generates a closure around the dbi_interp() function rather than sql_interp().

DEPENDENCIES

This module depends on SQL::Interpolate and DBI.

ADDITIONAL EXAMPLES

These are more advanced examples.

Binding variable types (DBI bind_param)

Compare this much simpler code to the example in SQL::Interpolate.

$dbx->selectall_arrayref(
    "SELECT * FROM mytable WHERE",
    "x=", \$x, "AND y=", sql_var(\$y, SQL_VARCHAR), "AND z IN",
    sql_var([1, 2], SQL_INTEGER)
);

DESIGN NOTES

Philosophy and requirements

DBIx::Interpolate is designed to look an feel like DBI even when the DBI interface is not entirely user friendly (e.g. the (fetch|select)(all|row)?_(array|hash)(ref)? and do methods). Still, the approach lowers the learning code and could simplify the process of converting existing DBI code over to SQL::Interpolate.

The use of statement handle sets (STX) is not strictly necessary but is rather designed to mimic DBI's statement handles more than anything else. The DBX object itself contains a statement handle set, which can be used for non-prepared calls such as to selectall_.*() methods (i.e. cache statement handles like in DBIx::Simple's keep_statements).

$dbx->stx()->max_sths(2);
$dbx->do(...) for 1..5;
$dbx->do(...) for 1..5;

An ideal solution would probably be to integrate SQL::Interpolate into DBIx::Simple rather than directly into DBI.

Proposed enhancements

The following enhancements to SQL::Interpolate have been proposed. The most important suggestions are listed at top, and some suggestions could be rejected.

DBI database handle and statement handle attributes are not currently exposed from the wrapper except via $dbx->dbh()->{...}. Maybe a Tie can be used. e.g. $dbx->{mysql_insert_id}

Support might be added for something analogous to DBI's bind_param_inout.

DBI's bind_param_array is not currently supported. A syntax as follows might be used:

"INSERT INTO mytable", [[...], [...], ...]

Passing identified variables:

my $x = {one => 'two'};
my $stx = $dbx->prepare("SELECT * FROM mytable WHERE", sql_var(\$x);
$stx->execute_vars();
...
$x->{two} = 'three';
$stx->execute_vars();
...

my $x = {one => 'two'};
my $y = {one => 'three', two => 'four'};
my $stx = $dbx->prepare("SELECT * FROM mytable WHERE", sql_var($x, 'x'));
$stx->execute_vars();
...
$stx->execute_vars(sql_var($x, 'x'); # or?
$stx->execute_vars(x => $x); # or?
...

Conditional macros: (made possible by late expansion of macros)

$blue = 1;
$z = 123;
$stx = $dbx->prepare(
    "SELECT * FROM mytable WHERE",
    sql_and( sql_if(\$blue,  "color = "blue""),
            sql_if(\$shape, sql("shape =", \$shape)),
            'z=', \$z),
    "LIMIT 10"
);
$stx->execute_vars();
$stx->selectall_arrayref();
$z = 234;
$stx->execute_vars();  # note: $sth unchanged
$stx->selectall_arrayref();
$blue = 0;
$stx->execute_vars();  # note: $sth changed
$stx->selectall_arrayref();

CONTRIBUTORS

David Manura (http://math2.org/david) (author). The existence and original design of this module as a wrapper around DBI was suggested by Jim Cromie.

FEEDBACK

Bug reports and comments on the design are most welcome. See the main SQL::Interpolate module for details.

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NAME

STATUS

SYNOPSIS

DESCRIPTION

Helper Functions you may need

`attr`

`key_field`

Database object (DBX) methods

Statement handle set (STX) methods

Internal functions

`dbi_interp`

`make_dbi_interp`

DEPENDENCIES

ADDITIONAL EXAMPLES

Binding variable types (DBI bind_param)

DESIGN NOTES

Philosophy and requirements

Proposed enhancements

CONTRIBUTORS

FEEDBACK

LEGAL

SEE ALSO

Other modules in this distribution

NAME

STATUS

SYNOPSIS

DESCRIPTION

Helper Functions you may need

attr

key_field

Database object (DBX) methods

Statement handle set (STX) methods

Internal functions

dbi_interp

make_dbi_interp

DEPENDENCIES

ADDITIONAL EXAMPLES

Binding variable types (DBI bind_param)

DESIGN NOTES

Philosophy and requirements

Proposed enhancements

CONTRIBUTORS

FEEDBACK

LEGAL

SEE ALSO

Other modules in this distribution

Module Install Instructions

`attr`

`key_field`

`dbi_interp`

`make_dbi_interp`