NAME

       UR::DataSource::File - Parent class for file-based data sources

DEPRECATED

       This module is deprecated.  Use UR::DataSource::Filesystem instead.

SYNOPSIS

         package MyNamespace::DataSource::MyFile;
         class MyNamespace::DataSource::MyFile {
             is => ['UR::DataSource::File', 'UR::Singleton'],
         };
         sub server { '/path/to/file' }
         sub delimiter { "\t" }
         sub column_order { ['thing_id', 'thing_name', 'thing_color' ] }
         sub sort_order { ['thing_id'] }

         package main;
         class MyNamespace::Thing {
             id_by => 'thing_id',
             has => [ 'thing_id', 'thing_name', 'thing_color' ],
             data_source => 'MyNamespace::DataSource::MyFile',
         }
         my @objs = MyNamespace::Thing->get(thing_name => 'Bob');

DESCRIPTION

       Classes which wish to retrieve their data from a regular file can use a
       UR::DataSource::File-based data source.  The modules implementing these data sources live
       under the DataSource subdirectory of the application's Namespace, by convention.  Besides
       defining a class for your data source inheriting from UR::DataSource::File, it should have
       the following methods, either as properties or functions in the package.

   Configuration
       These methods determine the configuration for your data source.

       server()
           server() should return a string representing the pathname of the file where the data
           is stored.

       file_list()
           The file_list() method should return a listref of pathnames to one or more identical
           files where data is stored.   Use file_list() instead of server() when you want to
           load-balance several NFS servers, for example.

           You must have either server() or file_list() in your module, but not both.  The
           existence of server() takes precedence over file_list().

       delimiter()
           delimiter() should return a string representing how the fields in each record are
           split into columns.  This string is interpreted as a regex internally.  The default
           delimiter is "\s*,\s*" meaning that the file is separated by commas.

       record_separator()
           record_separator() should return a string that gets stored in $/ before getline() is
           called on the file's filehandle.  The default record_separator() is "\n" meaning that
           the file's records are separated by newlines.

       skip_first_line()
           skip_first_line() should return a boolean value.  If true, the first line of the file
           is ignored, for example if the first line defines the columns in the file.

       column_order()
           column_order() should return a listref of column names in the file.  column_order is
           required; there is no default.

       sort_order()
           If the data file is sorted in some way, sort_order() should return a listref of column
           names (which must exist in column_order()) by which the file is sorted.  This gives
           the system a hint about how the file is structured, and is able to make shortcuts when
           reading the file to speed up data access.  The default is to assumme the file is not
           sorted.

INHERITANCE

         UR::DataSource

SEE ALSO

       UR, UR::DataSource