=head1 NAME

DBIx::Custom::Guides - DBIx::Custom Guides

=head1 GUIDES

=head2 1. Connect to the database

C<connect()> method create a new L<DBIx::Custom>
object and connect to the database.

    use DBIx::Custom;
    my $dbi = DBIx::Custom->connect(data_source => "dbi:mysql:database=dbname",
                                    user => 'ken', password => '!LFKD%$&');

If database is SQLite, use L<DBIx::Custom::SQLite> instead.
you connect database easily.

    use DBIx::Custom::SQLite;
    my $dbi = DBIx::Custom::SQLite->connect(database => 'dbname');
    
If database is  MySQL, use L<DBIx::Custom::MySQL>.

    use DBIx::Custom::MySQL;
    my $dbi = DBIx::Custom::MySQL->connect(
        database => 'dbname',
        user     => 'ken',
        password => '!LFKD%$&'
    );

=head2 2. Suger methods

L<DBIx::Custom> has suger methods, such as C<insert()>, C<update()>,
C<delete()> or C<select()>. If you want to do small works,
You don't have to create SQL statements.

=head3 insert()

Execute insert statement.

    $dbi->insert(table  => 'books',
                 param  => {title => 'Perl', author => 'Ken'});

The following SQL is executed.

    insert into (title, author) values (?, ?);

The values of C<title> and C<author> is embedded into the placeholders.

C<append> and C<filter> argument can be specified.
See also "METHODS" section.

=head3 update()

Execute update statement.

    $dbi->update(table  => 'books', 
                 param  => {title => 'Perl', author => 'Ken'}, 
                 where  => {id => 5});

The following SQL is executed.

    update books set title = ?, author = ?;

The values of C<title> and C<author> is embedded into the placeholders.

C<append> and C<filter> argument can be specified.
See also "METHOD" section.

If you want to update all rows, use C<update_all()> method.

=head3 delete()

Execute delete statement.

    $dbi->delete(table  => 'books',
                 where  => {author => 'Ken'});

The following SQL is executed.

    delete from books where id = ?;

The value of C<id> is embedded into the placehodler.

C<append> and C<filter> argument can be specified.
see also "METHODS" section.

If you want to delete all rows, use C<delete_all()> method.

=head3 select()

Execute select statement, only C<table> argument specified :

    my $result = $dbi->select(table => 'books');

The following SQL is executed.

    select * from books;

the result of C<select()> method is L<DBIx::Custom::Result> object.
You can fetch a row by C<fetch()> method.

    while (my $row = $result->fetch) {
        my $title  = $row->[0];
        my $author = $row->[1];
    }

L<DBIx::Custom::Result> has various methods to fetch row.
See "3. Fetch row".

C<column> and C<where> arguments specified.

    my $result = $dbi->select(
        table  => 'books',
        column => [qw/author title/],
        where  => {author => 'Ken'}
    );

The following SQL is executed.

    select author, title from books where author = ?;

the value of C<author> is embdded into the placeholder.

If you want to join tables, specify C<relation> argument. 

    my $result = $dbi->select(
        table    => ['books', 'rental'],
        column   => ['books.name as book_name']
        relation => {'books.id' => 'rental.book_id'}
    );

The following SQL is executed.

    select books.name as book_name from books, rental
    where books.id = rental.book_id;

If you want to add some string to the end of SQL statement,
use C<append> argument.

    my $result = $dbi->select(
        table  => 'books',
        where  => {author => 'Ken'},
        append => 'order by price limit 5',
    );

The following SQL is executed.

    select * books where author = ? order by price limit 5;

C<filter> argument can be specified.
see also "METHODS" section.

=head2 3. Fetch row

C<select()> method return L<DBIx::Custom::Result> object.
You can fetch row by various methods.
Note that in this section, array means array reference,
and hash meanse hash reference.

Fetch row into array.
    
    while (my $row = $result->fetch) {
        my $author = $row->[0];
        my $title  = $row->[1];
        
    }

Fetch only a first row into array.

    my $row = $result->fetch_first;

Fetch multiple rows into array of array.

    while (my $rows = $result->fetch_multi(5)) {
        my $first_author  = $rows->[0][0];
        my $first_title   = $rows->[0][1];
        my $second_author = $rows->[1][0];
        my $second_value  = $rows->[1][1];
    
    }
    
Fetch all rows into array of array.

    my $rows = $result->fetch_all;

Fetch row into hash.

    # Fetch a row into hash
    while (my $row = $result->fetch_hash) {
        my $title  = $row->{title};
        my $author = $row->{author};
        
    }

Fetch only a first row into hash

    my $row = $result->fetch_hash_first;
    
Fetch multiple rows into array of hash

    while (my $rows = $result->fetch_hash_multi(5)) {
        my $first_title   = $rows->[0]{title};
        my $first_author  = $rows->[0]{author};
        my $second_title  = $rows->[1]{title};
        my $second_author = $rows->[1]{author};
    
    }
    
Fetch all rows into array of hash

    my $rows = $result->fetch_hash_all;

If you want to access statement handle of L<DBI>, use C<sth> attribute.

    my $sth = $result->sth;

=head2 4. Hash parameter binding

L<DBIx::Custom> provides hash parameter binding.

At frist, I show normal parameter binding.

    use DBI;
    my $dbh = DBI->connect(...);
    my $sth = $dbh->prepare(
        "select * from books where author = ? and title like ?;"
    );
    $sth->execute('Ken', '%Perl%');

This is very good way because database system can enable SQL caching,
and parameter is quoted automatically. this is secure.

L<DBIx::Custom> hash parameter binding system improve
normal parameter binding to use hash parameter.

    my $result = $dbi->execute(
        "select * from books where {= author} and {like title};"
        param => {author => 'Ken', title => '%Perl%'}
    );

This is same as the normal way, execpt that the parameter is hash.
{= author} and {like title} is called C<tag>.
tag is expand to placeholder string internally.

    select * from books where {= author} and {like title}
      -> select * from books where author = ? and title like ?;

The following tags is available.

    [TAG]                       [REPLACED]
    {? NAME}               ->   ?
    {= NAME}               ->   NAME = ?
    {<> NAME}              ->   NAME <> ?
    
    {< NAME}               ->   NAME < ?
    {> NAME}               ->   NAME > ?
    {>= NAME}              ->   NAME >= ?
    {<= NAME}              ->   NAME <= ?
    
    {like NAME}            ->   NAME like ?
    {in NAME COUNT}        ->   NAME in [?, ?, ..]
    
    {insert_param NAME1 NAME2}   ->   (NAME1, NAME2) values (?, ?)
    {update_param NAME1 NAME2}   ->   set NAME1 = ?, NAME2 = ?

See also L<DBIx::Custom::QueryBuilder>.

C<{> and C<}> is reserved. If you use these charactors,
you must escape them using '\'. Note that '\' is
already perl escaped charactor, so you must write '\\'. 

    'select * from books \\{ something statement \\}'

=head2 5. Filtering

Usually, Perl string is kept as internal string.
If you want to save the string to database, You must encode the string.
Filtering system help you to convert a data to another data
when you save to the data and get the data form database.

If you want to register filter, use C<register_filter()> method.

    $dbi->register_filter(
        to_upper_case => sub {
            my $value = shift;
            return uc $value;
        }
    );

C<encode_utf8> and C<decode_utf8> filter is registerd by default.

You can specify these filters to C<filter> argument of C<execute()> method.

    my $result = $dbi->execute(
        "select * from books where {= author} and {like title};"
        param  => {author => 'Ken', title => '%Perl%'},
        filter => {author => 'to_upper_case, title => 'encode_utf8'}
    );

C<filter> argument can be specified to suger methods, such as
C<insert()>, C<update()>, C<update_all()>,
C<delete()>, C<delete_all()>, C<select()>.

    # insert(), having filter argument
    $dbi->insert(table  => 'books',
                 param  => {title => 'Perl', author => 'Ken'},
                 filter => {title => 'encode_utf8'});
    
    # select(), having filter argument
    my $result = $dbi->select(
        table  => 'books',
        column => [qw/author title/],
        where  => {author => 'Ken'},
        append => 'order by id limit 1',
        filter => {title => 'encode_utf8'}
    );

Filter works each parmeter, but you prepare default filter for all parameters.

    $dbi->default_bind_filter('encode_utf8');

C<filter()> argument overwrites this default filter.
    
    $dbi->default_bind_filter('encode_utf8');
    $dbi->insert(
        table  => 'books',
        param  => {title => 'Perl', author => 'Ken', price => 1000},
        filter => {author => 'to_upper_case', price => undef}
    );

This is same as the following example.

    $dbi->insert(
        table  => 'books',
        param  => {title => 'Perl', author => 'Ken', price => 1000},
        filter => {title => 'encode_uft8' author => 'to_upper_case'}
    );

You can also specify filter when the row is fetched. This is reverse of bind filter.

    my $result = $dbi->select(table => 'books');
    $result->filter({title => 'decode_utf8', author => 'to_upper_case'});

Filter works each column value, but you prepare a default filter
for all clumn value.

    $dbi->default_fetch_filter('decode_utf8');

C<filter()> method of L<DBIx::Custom::Result>
overwrites this default filter.

    $dbi->default_fetch_filter('decode_utf8');
    my $result = $dbi->select(
        table => 'books',
        columns => ['title', 'author', 'price']
    );
    $result->filter({author => 'to_upper_case', price => undef});

This is same as the following one.

    my $result = $dbi->select(
        table => 'books',
        columns => ['title', 'author', 'price']
    );
    $result->filter({title => 'decode_utf8', author => 'to_upper_case'});

Note that in fetch filter, column names must be lower case
even if the column name conatains upper case charactors.
This is requirment not to depend database systems.

=head2 6. Get high performance

=head3 Disable filter checking

Filter checking is executed by default.
This is done to check right filter name is specified,
but sometimes damage performance.

If you disable this filter checking,
Set C<filter_check> attribute to 0.

    $dbi->filter_check(0);

=head3 Use execute() method instead suger methods

If you execute insert statement by C<insert()> method,
you sometimes can't get required performance.

C<insert()> method is a little slow because SQL statement and statement handle
is created every time.

In that case, you can prepare a query by C<create_query()> method.
    
    my $query = $dbi->create_query(
        "insert into books {insert_param title author};"
    );

Return value of C<create_query()> is L<DBIx::Custom::Query> object.
This keep the information of SQL and column names.

    {
        sql     => 'insert into books (title, author) values (?, ?);',
        columns => ['title', 'author']
    }

Execute query repeatedly.
    
    my $inputs = [
        {title => 'Perl',      author => 'Ken'},
        {title => 'Good days', author => 'Mike'}
    ];
    
    foreach my $input (@$inputs) {
        $dbi->execute($query, $input);
    }

This is faster than C<insert()> method.

=head3 caching

C<execute()> method caches the parsed result of the source of SQL.
Default to 1

    $dbi->cache(1);

Caching is on memory, but you can change this by C<cache_method()>.
First argument is L<DBIx::Custom> object.
Second argument is a source of SQL,
such as "select * from books where {= title} and {= author};";
Third argument is parsed result, such as
{sql => "select * from books where title = ? and author = ?",
 columns => ['title', 'author']}, this is hash reference.
If arguments is more than two, this method is called to set cache.
If not, this method is called to get cache.

    $dbi->cache_method(sub {
        sub {
            my $self = shift;
            
            $self->{_cached} ||= {};
            
            # Set cache
            if (@_ > 1) {
                $self->{_cached}{$_[0]} = $_[1] 
            }
            
            # Get cache
            else {
                return $self->{_cached}{$_[0]}
            }
        }
    });

=head2 7. More features

=head3 Get DBI object

You can get L<DBI> object and call any method of L<DBI>.

    $dbi->dbh->begin_work;
    $dbi->dbh->commit;
    $dbi->dbh->rollback;

=head3 Change Result class

You can change Result class if you need.

    package Your::Result;
    use base 'DBIx::Custom::Result';
    
    sub some_method { ... }

    1;
    
    package main;
    
    use Your::Result;
    
    my $dbi = DBIx::Custom->connect(...);
    $dbi->result_class('Your::Result');

=head3 Custamize SQL builder object

You can custamize SQL builder object

    my $dbi = DBIx::Custom->connect(...);
    $dbi->query_builder->register_tag_processor(
        name => sub {
           ...
        }
    );

=head3 Resister helper method

You can resiter helper method.

    $dbi->helper(
        update_or_insert => sub {
            my $self = shift;
            # do something
        },
        find_or_create   => sub {
            my $self = shift;
            # do something
        }
    );

Register helper methods.
These method can be called from L<DBIx::Custom> object directory.

    $dbi->update_or_insert;
    $dbi->find_or_create;

=cut