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Data-Record-Serialize-0.32
River stage one • 1 direct dependent • 1 total dependent
++
/ Data::Record::Serialize

NAME

Data::Record::Serialize - Flexible serialization of a record

VERSION

version 0.32

SYNOPSIS

    use Data::Record::Serialize;

    # simple output to json
    $s = Data::Record::Serialize->new( encode => 'json', \%attr );
    $s->send( \%record );

    # cleanup record before sending
    $s = Data::Record::Serialize->new( encode => 'json',
        fields => [ qw( obsid chip_id phi theta ) ],
        format => 1,
        format_types => { N => '%0.4f' },
        format_fields => { obsid => '%05d' },
        rename_fields => { chip_id => 'CHIP' },
        types => { obsid => 'I', chip_id => 'S',
                   phi => 'N', theta => 'N' },
    );
    $s->send( \%record );


    # send to an SQLite database
    $s = Data::Record::Serialize->new(
        encode => 'dbi',
        dsn => [ 'SQLite', [ dbname => $dbname ] ],
        table => 'stuff',
        format => 1,
        fields => [ qw( obsid chip_id phi theta ) ],
        format_types => { N => '%0.4f' },
        format_fields => { obsid => '%05d' },
        rename_fields => { chip_id => 'CHIP' },
        types => { obsid => 'I', chip_id => 'S',
                   phi => 'N', theta => 'N' },
    );
    $s->send( \%record );

DESCRIPTION

Data::Record::Serialize encodes data records and sends them somewhere. This module is primarily useful for output of sets of uniformly structured data records. It provides a uniform, thin, interface to various serializers and output sinks. Its raison d'etre is its ability to manipulate the records prior to encoding and output.

  • A record is a collection of fields, i.e. keys and scalar values.

  • All records are assumed to have the same structure.

  • Fields may have simple types.

  • Fields may be renamed upon output.

  • A subset of the fields may be selected for output.

  • Field values may be transformed prior to output.

Types

Some output encoders care about the type of a field. Data::Record::Serialize recognizes these types:

  • N - Number (any number)

  • I - Integer

  • S - String

  • B - Boolean

Not all encoders support separate integer or Boolean types. Where not supported, integers are encoded as numbers and Booleans as integers.

Types may be specified for fields, or may be automatically determined from the first record which is output. It is not possible to deterministically determine if a field is Boolean, so such fields must be explicitly specified. Boolean fields should be "truthy", e.g., when used in a conditional, they evaluate to true or false.

Field transformation

Transformations can be applied to fields prior to output, and may be specified globally for data types as well as for specifically for fields. The latter take precedence.

Transformations are specified via the "format_fields" and "format_types" parameters. They can either be a sprintf compatible format string,

    format_types => { N => '%0.4f' },
    format_fields => { obsid => '%05d' },

 or a code reference:

    format_types => { B => sub { Lingua::Boolean::Tiny::boolean( $_[0] ) } }

Encoders

The available encoders and their respective documentation are:

Sinks

Sinks are where encoded data are sent.

The available sinks and their documentation are:

Refer to the documentation for additional constructor options, and object and class methods and attributes;

Fields and their types

Which fields are output and how their types are determined depends upon the "fields", "types", and "default_type" attributes.

This seems a bit complicated, but the idea is to provide a DWIM interface requiring minimal specification.

In the following table:

 N   => not specified
 Y   => specified
 X   => doesn't matter
 all => the string 'all'

Automatic type determination is done by examining the first record sent to the output stream.

Automatic output field determination is done by examining the first record sent to the output stream. Only those fields will be output for subsequent records.

  fields types default_type  Result
  ------ ----- ------------  ------

  N/all   N        N         Output fields are automatically determined.
                             Types are automatically determined.

  N/all   N        Y         Output fields are automatically determined.
                             Types are set to <default_type>.

    Y     N        N         Fields in <fields> are output.
                             Types are automatically determined.

    Y     Y        N         Fields in <fields> are output.
                             Fields in <types> get the specified type.
                             Types for other fields are automatically determined.

    Y     Y        Y         Fields in <fields> are output.
                             Fields in <types> get the specified type.
                             Types for other fields are set to <default_type>.

   all    Y        N         Output fields are automatically determined.
                             Fields in <types> get the specified type.
                             Types for other fields are automatically determined.

   all    Y        Y         Output fields are automatically determined.
                             Fields in <types> get the specified type.
                             Types for other fields are set to <default_type>.

    N     Y        X         Fields in <types> are output.
                             Types are specified by <types>.

Errors

Most errors result in exception objects being thrown, typically in the Data::Record::Serialize::Error hierarchy.

CLASS METHODS

new

  $s = Data::Record::Serialize->new( %args );
  $s = Data::Record::Serialize->new( \%args );

Construct a new object. In addition to any arguments required or provided by the specified encoders and sinks, the following arguments are recognized:

types => hashref|arrayref

This specifies types (N, I, S, B ) for fields.

If an array, the fields will be output in the specified order, provided the encoder permits it (see below, however). For example,

  # use order if possible
  types => [ c => 'N', a => 'N', b => 'N' ]

  # order doesn't matter
  types => { c => 'N', a => 'N', b => 'N' }

If "fields" is specified, then its order will override that specified here.

To understand how this attribute works in concert with "fields" and "default_type", please see "Fields and their types".

default_type => S|N|I|B

The default input type for fields whose types were not specified via the "types".

To understand how this attribute works in concert with "fields" and "types", please see "Fields and their types".

fields => arrayref|all

The fields to output. If it is the string all, all input fields will be output. If it is an arrayref, the fields will be output in the specified order, provided the encoder permits it.

To understand how this attribute works in concert with "types" and "default_type", please see "Fields and their types".

encode => encoder

Required. The module which will encode the data.

With no prefix, it is assumed to be in the Data::Record::Serialize::Encode namespace. With a prefix of + it is a fully qualified module name.

Specific encoders may provide additional, or require specific, attributes. See "Encoders" for more information.

sink => sink

The module which writes the encoded data.

With no prefix, it is assumed to be in the Data::Record::Serialize::Sink namespace. With a prefix of + it is a fully qualified module name.

Specific sinks may provide additional, or require specific attributes. See "Sinks" for more information.

The value is stream (corresponding to Data::Record::Serialize::Sink::stream), unless the encoder is also a sink.

It is an error to specify a sink if the encoder already acts as one.

nullify => arrayref|coderef|Boolean

Fields that should be set to undef if they are empty. Sinks should encode undef as the null value.

nullify may be passed:

  • an arrayref of input field names

  • a coderef

    The coderef is called as

      @input_field_names = $code->( $serializer_object )

  • a Boolean

    If true, all field names are added to the list. When false, the list is emptied.

Names are verified against the input fields after the first record is sent. A Data::Record::Serialize::Error::Role::Base::fields error is thrown if non-existent fields are specified.

numify => arrayref|coderef|Boolean

Specify fields that should be explicitly transformed into a number. It defaults to false, unless a particular encoder requires it (e.g. json). To avoid unnecessary conversion overhead, set this to false if you are sure that your data are appropriately numified, or if only a few fields need to be transformed and can be done via the "format_fields" option.

numify may be passed:

  • an arrayref of input field names

  • a coderef

    The coderef is called as

      @input_field_names = $code->( $serializer_object )

  • a Boolean

    If true, all numeric fields are added to the list. When false, the list is emptied.

Names are verified against the input fields after the first record is sent. A Data::Record::Serialize::Error::Role::Base::fields error is thrown if non-existent fields are specified.

stringify => arrayref|coderef|Boolean

Specify fields that should be explicitly transformed into a string. It defaults to false, unless a particular encoder requires it (e.g. json). To avoid unnecessary conversion overhead, set this to false if you are sure that your data are appropriately stringified, or if only a few fields need to be transformed and can be done via the "format_fields" option.

stringify may be passed:

  • an arrayref of input field names

  • a coderef

    The coderef is called as

      @input_field_names = $code->( $serializer_object )

  • a Boolean

    If true, all string fields are added to the list. When false, the list is emptied.

Names are verified against the input fields after the first record is sent. A Data::Record::Serialize::Error::Role::Base::fields error is thrown if non-existent fields are specified.

format => Boolean

If true, format the output fields using the formats specified in the "format_fields" and/or "format_types" options. The default is true.

format_fields => hashref

Specify transforms specific to fields. The hash keys are input field names; each value is either a sprintf style format or a coderef. The transformations will be applied prior to encoding the record, but only if the "format" attribute is also set. Formats specified here override those specified in "format_types".

The coderef will be called with the value to format as its first argument, and should return the formatted value.

format_types => hashref

Specify transforms specific to types. The hash keys are field types (N, I, S, B); each value is either a sprintf style format or a coderef. The transformations will be applied prior to encoding the record, but only if the "format" attribute is also set. Formats specified here may be overridden for specific fields using the "format_fields" attribute.

The coderef will be called with the value to format as its first argument, and should return the formatted value.

rename_fields => hashref

A hash mapping input to output field names. By default the input field names are used unaltered.

METHODS

For additional methods, see the following modules

"Data::Serialize::Record::Role::Base"
"Data::Serialize::Record::Role::Default"
"Data::Serialize::Record::Encode"
"Data::Serialize::Record::Sink",

send

  $s->send( \%record );

Encode and send the record to the associated sink.

WARNING: the passed hash is modified. If you need the original contents, pass in a copy.

ATTRIBUTES

Object attributes are provided by the following modules

"Data::Serialize::Record::Role::Base"
"Data::Serialize::Record::Role::Default"
"Data::Serialize::Record::Encode"
"Data::Serialize::Record::Sink",

EXAMPLES

Generate a JSON stream to the standard output stream

  $s = Data::Record::Serialize->new( encode => 'json' );

Only output select fields

  $s = Data::Record::Serialize->new(
    encode => 'json',
    fields => [ qw( obsid chip_id phi theta ) ],
   );

Format numeric fields

  $s = Data::Record::Serialize->new(
    encode => 'json',
    fields => [ qw( obsid chip_id phi theta ) ],
    format => 1,
    format_types => { N => '%0.4f' },
   );

Override formats for specific fields

  $s = Data::Record::Serialize->new(
    encode => 'json',
    fields => [ qw( obsid chip_id phi theta ) ],
    format_types => { N => '%0.4f' },
    format_fields => { obsid => '%05d' },
   );

Rename fields

  $s = Data::Record::Serialize->new(
    encode => 'json',
    fields => [ qw( obsid chip_id phi theta ) ],
    format_types => { N => '%0.4f' },
    format_fields => { obsid => '%05d' },
    rename_fields => { chip_id => 'CHIP' },
   );

Specify field types

  $s = Data::Record::Serialize->new(
    encode => 'json',
    fields => [ qw( obsid chip_id phi theta ) ],
    format_types => { N => '%0.4f' },
    format_fields => { obsid => '%05d' },
    rename_fields => { chip_id => 'CHIP' },
    types => { obsid => 'N', chip_id => 'S', phi => 'N', theta => 'N' }'
   );

Switch to an SQLite database in $dbname

  $s = Data::Record::Serialize->new(
    encode => 'dbi',
    dsn => [ 'SQLite', [ dbname => $dbname ] ],
    table => 'stuff',
    fields => [ qw( obsid chip_id phi theta ) ],
    format_types => { N => '%0.4f' },
    format_fields => { obsid => '%05d' },
    rename_fields => { chip_id => 'CHIP' },
    types => { obsid => 'N', chip_id => 'S', phi => 'N', theta => 'N' }'
   );

SUPPORT

Bugs

Please report any bugs or feature requests to bug-data-record-serialize@rt.cpan.org or through the web interface at: https://rt.cpan.org/Public/Dist/Display.html?Name=Data-Record-Serialize

Source

Source is available at

  https://gitlab.com/djerius/data-record-serialize

and may be cloned from

  https://gitlab.com/djerius/data-record-serialize.git

SEE ALSO

Please see those modules/websites for more information related to this module.

AUTHOR

Diab Jerius <djerius@cpan.org>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2017 by Smithsonian Astrophysical Observatory.

This is free software, licensed under:

  The GNU General Public License, Version 3, June 2007