Juerd Waalboer > DBIx-Simple > DBIx::Simple

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Module Version: 1.35   Source  

NAME ^

DBIx::Simple - Very complete easy-to-use OO interface to DBI

SYNOPSIS ^

DBIx::Simple

    $db = DBIx::Simple->connect(...)  # or ->new

    $db->keep_statements = 16
    $db->lc_columns = 1
    $db->result_class = 'DBIx::Simple::Result';

    $db->begin_work         $db->commit
    $db->rollback           $db->disconnect
    $db->func(...)          $db->last_insert_id

    $result = $db->query(...)

DBIx::SImple + SQL::Interp

    $result = $db->iquery(...)

DBIx::Simple + SQL::Abstract

    $db->abstract = SQL::Abstract->new(...)

    $result = $db->select(...)
    $result = $db->insert(...)
    $result = $db->update(...)
    $result = $db->delete(...)

DBIx::Simple::Result

    @columns = $result->columns

    $result->into($foo, $bar, $baz)
    $row = $result->fetch

    @row = $result->list      @rows = $result->flat
    $row = $result->array     @rows = $result->arrays
    $row = $result->hash      @rows = $result->hashes
    @row = $result->kv_list   @rows = $result->kv_flat
    $row = $result->kv_array  @rows = $result->kv_arrays
    $obj = $result->object    @objs = $result->objects

    %map = $result->map_arrays(...)
    %map = $result->map_hashes(...)
    %map = $result->map

    $rows = $result->rows

    $dump = $result->text

    $result->finish

DBIx::Simple::Result + DBIx::XHTML_Table

    $html = $result->html(...)

    $table_object = $result->xto(...)

Examples

Please read DBIx::Simple::Examples for code examples.

DESCRIPTION ^

DBIx::Simple provides a simplified interface to DBI, Perl's powerful database module.

This module is aimed at rapid development and easy maintenance. Query preparation and execution are combined in a single method, the result object (which is a wrapper around the statement handle) provides easy row-by-row and slurping methods.

The query method returns either a result object, or a dummy object. The dummy object returns undef (or an empty list) for all methods and when used in boolean context, is false. The dummy object lets you postpone (or skip) error checking, but it also makes immediate error checking simply $db->query(...) or die $db->error.

DBIx::Simple methods

Class methods

connect($dbh), connect($dsn, $user, $pass, \%options)
new($dbh), new($dsn, $user, $pass, \%options)

The connect or new class method takes either an existing DBI object ($dbh), or a list of arguments to pass to DBI->connect. See DBI for a detailed description.

You cannot use this method to clone a DBIx::Simple object: the $dbh passed should be a DBI::db object, not a DBIx::Simple object.

For new connections, PrintError is disabled by default. If you enable it, beware that it will report line numbers in DBIx/Simple.pm.

For new connections, RaiseError is enabled by default unless the environment variable PERL_DBIX_SIMPLE_NO_RAISEERROR is set to a non-empty non-0 value.

This method is the constructor and returns a DBIx::Simple object on success. On failure, it returns undef.

Object methods

query($query, @values)

Prepares and executes the query and returns a result object.

If the string (??) is present in the query, it is replaced with a list of as many question marks as @values.

The database drivers substitute placeholders (question marks that do not appear in quoted literals) in the query with the given @values, after them escaping them. You should always use placeholders, and never use raw user input in database queries.

On success, returns a DBIx::Simple::Result object. On failure, returns a DBIx::Simple::Dummy object.

iquery(...)

Uses SQL::Interp to interpolate values into a query, and uses the resulting generated query and bind arguments with query. See SQL::Interp's documentation for usage information.

Requires Mark Storberg's SQL::Interp, which is available from CPAN. SQL::Interp is a fork from David Manura's SQL::Interpolate.

select, insert, update, delete

Calls the respective method on abstract, and uses the resulting generated query and bind arguments with query. See SQL::Abstract's documentation for usage information. You can override the object by assigning to the abstract property.

Requires Nathan Wiger's SQL::Abstract, which is available from CPAN.

begin_work, begin, commit, rollback

These transaction related methods call the DBI respective methods and Do What You Mean. See DBI for details.

begin is an alias for begin_work.

func(...)

Calls the func method of DBI. See DBI for details.

last_insert_id(...)

Calls the last_insert_id method of DBI. See DBI for details. Note that this feature requires DBI 1.38 or newer.

disconnect

Destroys (finishes) active statements and disconnects. Whenever the database object is destroyed, this happens automatically if DBIx::Simple handled the connection (i.e. you didn't use an existing DBI handle). After disconnecting, you can no longer use the database object or any of its result objects.

Object properties

dbh

Exposes the internal database handle. Use this only if you know what you are doing. Keeping a reference or doing queries can interfere with DBIx::Simple's garbage collection and error reporting.

lc_columns = $bool

When true at time of query execution, makes several result object methods use lower cased column names. lc_columns is true by default.

keep_statements = $integer

Sets the number of statement objects that DBIx::Simple can keep for reuse. This can dramatically speed up repeated queries (like when used in a loop). keep_statements is 16 by default.

A query is only reused if it equals a previously used one literally. This means that to benefit from this caching mechanism, you must use placeholders and never interpolate variables yourself.

    # Wrong:
    $db->query("INSERT INTO foo VALUES ('$foo', '$bar', '$baz')");
    $db->query("SELECT FROM foo WHERE foo = '$foo' OR bar = '$bar'");

    # Right:
    $db->query('INSERT INTO foo VALUES (??)', $foo, $bar, $baz);
    $db->query('SELECT FROM foo WHERE foo = ? OR bar = ?', $foo, $baz);

Of course, automatic value escaping is a much better reason for using placeholders.

result_class = $string

Class to use for result objects. Defaults to DBIx::Simple::Result. A constructor is not used.

error

Returns the error string of the last DBI method. See the discussion of "err" and "errstr" in DBI.

abstract = SQL::Abstract->new(...)

Sets the object to use with the select, insert, update and delete methods. On first access, will create one with SQL::Abstract's default options.

Requires Nathan Wiger's SQL::Abstract, which is available from CPAN.

In theory, you can assign any object to this property, as long as that object has these four methods, and they return a list suitable for use with the query method.

DBIx::Simple::Dummy

The query method of DBIx::Simple returns a dummy object on failure. Its methods all return an empty list or undef, depending on context. When used in boolean context, a dummy object evaluates to false.

DBIx::Simple::Result methods

Methods documented to return "a list" return a reference to an array of the same in scalar context, unless something else is explicitly mentioned.

columns

Returns a list of column names. Affected by lc_columns.

bind(LIST)

Binds the given LIST of variables to the columns. Unlike with DBI's bind_columns, passing references is not needed.

Bound variables are very efficient. Binding a tied variable doesn't work.

attr(...)

Returns a copy of an sth attribute (property). See "Statement Handle Attributes" in DBI for details.

func(...)

This calls the func method on the sth of DBI. See DBI for details.

rows

Returns the number of rows affected by the last row affecting command, or -1 if the number of rows is not known or not available.

For SELECT statements, it is generally not possible to know how many rows are returned. MySQL does provide this information. See DBI for a detailed explanation.

finish

Finishes the statement. After finishing a statement, it can no longer be used. When the result object is destroyed, its statement handle is automatically finished and destroyed. There should be no reason to call this method explicitly; just let the result object go out of scope.

Fetching a single row at a time

fetch

Returns a reference to the array that holds the values. This is the same array every time.

Subsequent fetches (using any method) may change the values in the variables passed and the returned reference's array.

into(LIST)

Combines bind with fetch. Returns what fetch returns.

list

Returns a list of values, or (in scalar context), only the last value.

array

Returns a reference to an array.

hash

Returns a reference to a hash, keyed by column name. Affected by lc_columns.

kv_list

Returns an ordered list of interleaved keys and values. Affected by lc_columns.

kv_array

Returns a reference to an array of interleaved column names and values. Like kv, but returns an array reference even in list context. Affected by lc_columns.

object($class, ...)

Returns an instance of $class. See "Object construction". Possibly affected by lc_columns.

Fetching all remaining rows

flat

Returns a flattened list.

arrays

Returns a list of references to arrays

hashes

Returns a list of references to hashes, keyed by column name. Affected by lc_columns.

kv_flat

Returns an flattened list of interleaved column names and values. Affected by lc_columns.

kv_arrays

Returns a list of references to arrays of interleaved column names and values. Affected by lc_columns.

objects($class, ...)

Returns a list of instances of $class. See "Object construction". Possibly affected by lc_columns.

map_arrays($column_number)

Constructs a hash of array references keyed by the values in the chosen column, and returns a list of interleaved keys and values, or (in scalar context), a reference to a hash.

map_hashes($column_name)

Constructs a hash of hash references keyed by the values in the chosen column, and returns a list of interleaved keys and values, or (in scalar context), a reference to a hash. Affected by lc_columns.

map

Constructs a simple hash, using the two columns as key/value pairs. Should only be used with queries that return two columns. Returns a list of interleaved keys and values, or (in scalar context), a reference to a hash.

xto(%attr)

Returns a DBIx::XHTML_Table object, passing the constructor a reference to %attr.

Requires Jeffrey Hayes Anderson's DBIx::XHTML_Table, which is available from CPAN.

In general, using the html method (described below) is much easier. xto is available in case you need more flexibility. Not affected by lc_columns.

html(%attr)

Returns an (X)HTML formatted table, using the DBIx::XHTML_Table module. Passes a reference to %attr to both the constructor and the output method.

Requires Jeffrey Hayes Anderson's DBIx::XHTML_Table, which is available from CPAN.

This method is a shortcut method. That means that

    $result->html

    $result->html(
        tr => { bgcolor => [ 'silver', 'white' ] },
        no_ucfirst => 1
    )

do the same as:

    $result->xto->output

    $result->xto(
        tr => { bgcolor => [ 'silver', 'white' ] }
    )->output(
        no_ucfirst => 1
    );
text($type)

Returns a string with a simple text representation of the data. $type can be any of: neat, table, box. It defaults to table if Text::Table is installed, to neat if it isn't.

table and box require Anno Siegel's Text::Table, which is available from CPAN.

Object construction

DBIx::Simple has basic support for returning results as objects. The actual construction method has to be provided by the chosen class, making this functionality rather advanced and perhaps unsuited for beginning programmers.

When the object or objects method is called on the result object returned by one of the query methods, two approaches are tried. In either case, pass the name of a class as the first argument. A prefix of a single colon can be used as an alias for DBIx::Simple::Result::, e.g. ":Example" is short for "DBIx::Simple::Result::Example". When this shortcut is used, the corresponding module is loaded automatically.

The default class when no class is given, is :RowObject. It requires Jos Boumans' Object::Accessor, which is available from CPAN.

Simple object construction

When object is given a class that provides a new method, but not a new_from_dbix_simple method, new is called with a list of interleaved column names and values, like a flattened hash, but ordered. objects causes new to be called multiple times, once for each remaining row.

Example:

    {
        package DBIx::Simple::Result::ObjectExample;
        sub new {
            my ($class, %args) = @_;
            return bless $class, \%args;
        }

        sub foo { ... }
        sub bar { ... }
    }


    $db->query('SELECT foo, bar FROM baz')->object(':ObjectExample')->foo();

Advanced object construction

When object or objects is given a class that provides a new_from_dbix_simple method, any new is ignored, and new_from_dbix_simple is called with a list of the DBIx::Simple::Result object and any arguments passed to object or objects.

new_from_dbix_simple is called in scalar context for object, and in list context for objects. In scalar context, it should fetch exactly one row, and in list context, it should fetch all remaining rows.

Example:

    {
        package DBIx::Simple::Result::ObjectExample;
        sub new_from_dbix_simple {
            my ($class, $result, @args) = @_;
            return map { bless $class, $_ } $result->hashes if wantarray;
            return       bless $class, $result->hash;
        }

        sub foo { ... }
        sub bar { ... }
    }

    $db->query('SELECT foo, bar FROM baz')->object(':ObjectExample')->foo();

MISCELLANEOUS ^

The mapping methods do not check whether the keys are unique. Rows that are fetched later overwrite earlier ones.

LICENSE ^

Pick your favourite OSI approved license :)

http://www.opensource.org/licenses/alphabetical

AUTHOR ^

Juerd Waalboer <#####@juerd.nl> <http://juerd.nl/>

SEE ALSO ^

perl, perlref

DBI, DBIx::Simple::Examples, SQL::Abstract, DBIx::XHTML_Table

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