focal (3) Data::TableReader.3pm.gz
NAME
Data::TableReader - Extract records from "dirty" tabular data sources
VERSION
version 0.010
SYNOPSIS
# Find a row in the Excel file containing the headers
# "address", "city", "state", "zip" (in any order)
# and then convert each row under that into a hashref of those fields.
my $records= Data::TableReader>new(
input => 'path/to/file.xlsx',
fields => [qw( address city state zip )],
)
->iterator->all;
but there's plenty of options to choose from...
my $tr= Data::TableReader->new(
# path or file handle
# let it auto-detect the format (but can override that if we need)
input => 'path/to/file.csv',
# We want these fields to exist in the file (identified by headers)
fields => [
{ name => 'address', header => qw/street|address/i },
'city',
'state',
# can validate with Type::Tiny classes
{ name => 'zip', header => qw/zip\b|postal/i, type => US_Zipcode },
],
# Our data provider is horrible; just ignore any nonsense we encounter
on_blank_row => 'next',
on_validation_fail => 'next',
# Capture warnings and show to user who uploaded file
log => \(my @messages)
);
my $records= $tr->iterator->all;
...
$http_response->body( encode_json({ messages => \@messages }) );
DESCRIPTION
This module is designed to be a useful for anyone who needs to take "loose" or "dirty" tabular data
sources (such as Excel, CSV, TSV, or HTML) which may have been edited by non-technical humans and extract
the data into sanitized records, while also verifying that the data file contains roughly the schema you
were expecting. It is primarily intended for making automated imports of data from non-automated or
unstable sources, and providing human-readable feedback about the validity of the data file.
ATTRIBUTES
input
This can be a file name or Path::Class instance or file handle or a Spreadsheet::ParseExcel::Worksheet
object. If a file handle, it must be seekable in order to auto-detect the file format, or you may
specify the decoder directly to avoid auto-detection.
decoder
This is either an instance of Data::TableReader::Decoder, or a class name, or a partial class name to be
appended as "Data::TableReader::Decoder::$name" or an arrayref or hashref of arguments to build the
decoder.
In an arrayref the first argument can be undef, and in a hashref the CLASS argument can be missing or
undef. In those cases it will be detected from the input attribute and any default arguments combined
with (and if necessary trumped by) the extra arguments in the arrayref or hashref.
Examples:
'CSV'
# becomes Data::TableReader::Decoder::CSV->new()
[ 'CSV', sep_char => "|" ]
# becomes Data::TableReader::Decoder::CSV->new(sep_char => "|")
{ CLASS => 'CSV', sep_char => "|" }
# becomes Data::TableReader::Decoder::CSV->new({ sep_char => "|" })
fields
An arrayref of Data::TableReader::Field objects (or hashrefs to construct them with) which this module
should search for within the tables (worksheets etc.) of "input".
record_class
Default is the special value 'HASH' for un-blessed hashref records. The special value 'ARRAY' will
result in arrayrefs with fields in the same order they were specified in the "fields" specification.
Setting it to anything else will return records created with "$record_class->new(\%fields);"
static_field_order
Boolean, whether the "fields" must be found in columns in the exact order that they were specified.
Default is false.
header_row_at
Row number, or range of row numbers where the header must be found. (All row numbers in this module are
1-based, to match end-user expectations.) The default is "[1,10]" to limit header scanning to the first
10 rows. As a special case, if you are reading a source which lacks headers and you trust the source to
deliver the columns in the right order, you can set this to undef if you also set "static_field_order =>
1".
on_unknown_columns
on_unknown_columns => 'use' # warn, and then use the table
on_unknown_columns => 'next' # warn, and then look for another table which matches
on_unknown_columns => 'die' # fatal error
on_unknown_columns => sub {
my ($reader, $col_headers)= @_;
...;
return $opt; # one of the above values
}
This determines handling for columns that aren't associated with any field. The "required" columns must
all be found before it considers this setting, but once it has found everything it needs to make this a
candidate, you might or might not care about the leftover columns.
'use' (default)
You don't care if there are extra columns, just log warnings about them and proceed extracting from
this table.
'next'
Extra columns mean that you didn't find the table you wanted. Log the near-miss, and keep searching
additional rows or additional tables.
'die'
This header is probably what you want, but you consider extra columns to be an error condition. Logs
the details and calls "croak".
"sub {}"
You can add your own logic to handle this. Inspect the headers however you like, and then return one
of the above values.
on_blank_rows
on_blank_rows => 'next' # warn, and then skip the row(s)
on_blank_rows => 'last' # warn, and stop iterating the table
on_blank_rows => 'die' # fatal error
on_blank_rows => 'use' # actually try to return the blank rows as records
on_blank_rows => sub {
my ($reader, $first_blank_rownum, $last_blank_rownum)= @_;
...;
return $opt; # one of the above values
}
This determines what happens when you've found the table, are extracting records, and encounter a series
of blank rows (defined as a row with no printable characters in any field) followed by non-blank rows.
If you use the callback, it suppresses the default warning, since you can generate your own.
The default is 'next'.
on_validation_fail
on_validation_fail => 'next' # warn, and then skip the record
on_validation_fail => 'use' # warn, and then use the record anyway
on_validation_fail => 'die' # fatal error
on_validation_fail => sub {
my ($reader, $failures, $values, $context)= @_;
for (@$failures) {
my ($field, $value_index, $message)= @$_;
...
# $field is a Data::TableReader::Field
# $values->[$value_index] is the string that failed validation
# $message is the error returned from the validation function
# $context is a string describing the source of the row, like "Row 5"
# You may modify $values to alter the record that is about to be created
}
# Clear the failures array to suppress warnings, if you actually corrected
# the validation problems.
@$failures= () if $opt eq 'use';
# return one of the above constants to tell the iterator what to do next
return $opt;
}
This determines what happens when you've found the table, are extracting records, and one row fails its
validation. In addition to deciding an option, the callback gives you a chance to alter the record
before 'use'ing it. If you use the callback, it suppresses the default warning, since you can generate
your own.
The default is 'die'.
log
If undefined (the default) all log messages above 'info' will be emitted with "warn "$message\n"". If
set to an object, it should support an API of:
trace, is_trace
debug, is_debug
info, is_info
warn, is_warn
error, is_error
such as Log::Any and may other perl logging modules use. You can also set it to a coderef such as:
my @messages;
sub { my ($level, $message)= @_;
push @messages, [ $level, $message ]
if grep { $level eq $_ } qw( info warn error );
};
for a simple way to capture the messages without involving a logging module. And for extra convenience,
you can set it to an arrayref which will receive any message that would otherwise have gone to 'warn' or
'error'.
METHODS
detect_input_format
my ($class, @args)= $tr->detect_input_format( $filename, $head_of_file );
This is used internally to detect the format of a file, but you can call it manually if you like. The
first argument (optional) is a file name, and the second argument (also optional) is the first few
hundred bytes of the file. Missing arguments will be pulled from "input" if possible. The return value
is the best guess of module name and constructor arguments that should be used to parse the file.
However, this doesn't guarantee such module actually exists or is installed; it might just echo the file
extension back to you.
find_table
if ($tr->find_table) { ... }
Search through the input for the beginning of the records, identified by a header row matching the
various constraints defined in "fields". If "header_row_at" is undef, then this does nothing and assumes
success.
Returns a boolean of whether it succeeded. This method does not "croak" on failure like "iterator" does,
on the assumption that you want to handle them gracefully. All diagnostics about the search are logged
via "log".
col_map
This is a lazy attribute from table detection. After calling "find_table" you can inspect which fields
were found for each column via this method. If called before "find_table", this triggers table detection
and throws an exception if one isn't found.
Returns an arrayref with one element for each column, each undefined or a reference to the Field object
it matched.
field_map
This is another lazy attribute from table detection, mapping from field name to column index/indicies
which the field will be loaded from. If called before "find_table", this triggers table detection and
throws an exception if one isn't found.
Returns a hashref where key is the field name, and value is either a single column index, or an arrayref
of column indicies if the field is an array field.
iterator
my $iter= $tr->iterator;
while (my $rec= $iter->()) { ... }
Create an iterator. If the table has not been located, then find it and "croak" if it can't be found.
Depending on the decoder and input filehandle, you might only be able to have one instance of the
iterator at a time.
The iterator derives from Data::TableReader::Iterator but also has a method "all" which returns all
records in an arrayref.
my $records= $tr->iterator->all;
THANKS
Portions of this software were funded by Ellis, Partners in Management Solutions
<http://www.epmsonline.com/>.
AUTHOR
Michael Conrad <mike@nrdvana.net>
CONTRIBUTOR
Christian Walde <walde.christian@gmail.com>
COPYRIGHT AND LICENSE
This software is copyright (c) 2019 by Michael Conrad.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
programming language system itself.