Data::Printer::Filter::DB(3) pretty printing database objects


In your program:

use Data::Printer filters => {
-external => [ 'DB' ],

or, in your ".dataprinter" file:

    filters => {
      -external => [ 'DB' ],


This is a filter plugin for Data::Printer. It filters through DBI's handlers (dbh) and statement (sth) objects displaying relevant information for the user. It also filters any object which inherits from DBIx::Class::Schema, DBIx::Class::ResultSet or DBIx::Class::ResultSetColumn.

DBI Sample Output

DBI is an extremely powerful and complete database interface. But it does a lot of magic under the hood, making their objects somewhat harder to debug. This filter aims to fix that :)

For instance, say you want to debug something like this:

  use DBI;
  my $dbh = DBI->connect('dbi:DBM(RaiseError=1):', undef, undef );

A regular Data::Dumper output gives you absolutely nothing:

$VAR1 = bless( {}, 'DBI::db' );

Data::Printer makes it better, but only to debug the class itself, not helpful at all to see its contents and debug your own code:

    DBI::db  {
        Parents       DBI::common
        Linear @ISA   DBI::db, DBI::common
        public methods (48) : begin_work, clone, column_info, commit, connected, data_sources, disconnect, do, foreign_key_info, get_info, last_insert_id, ping, prepare, prepare_cached, preparse, primary_key, primary_key_info, quote, quote_identifier, rollback, rows, selectall_arrayref, selectall_hashref, selectcol_arrayref, selectrow_array, selectrow_arrayref, selectrow_hashref, sqlite_backup_from_file, sqlite_backup_to_file, sqlite_busy_timeout, sqlite_collation_needed, sqlite_commit_hook, sqlite_create_aggregate, sqlite_create_collation, sqlite_create_function, sqlite_enable_load_extension, sqlite_last_insert_rowid, sqlite_progress_handler, sqlite_register_fts3_perl_tokenizer, sqlite_rollback_hook, sqlite_set_authorizer, sqlite_update_hook, statistics_info, table_info, tables, take_imp_data, type_info, type_info_all
        private methods (0)
        internals: {

Fear no more! If you use this filter, here's what you'll see:

    SQLite Database Handle (connected) {
        dbname: file.db
        Auto Commit: 1
        Statement Handles: 0
        Last Statement: -

Much better, huh? :)

Statement handlers are even better. Imagine you continued your code with something like:

  my $sth = $dbh->prepare('SELECT * FROM foo WHERE bar = ?');

With this filter, instead of an empty dump or full method information, you'll get exactly what you came for:

 SELECT * FROM foo WHERE bar = ?  (42)

Note that if your driver does not support holding of parameter values, you'll get a "bindings unavailable" message instead of the bound values.