Dave Rolsky > Fey-0.40 > Fey::Literal::Term

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Module Version: 0.40   Source  

NAME ^

Fey::Literal::Term - Represents a literal term in a SQL statement

VERSION ^

version 0.40

SYNOPSIS ^

  my $term = Fey::Literal::Term->new(@anything)

DESCRIPTION ^

This class represents a literal term in a SQL statement. A "term" in this module means a literal SQL snippet that will be used verbatim, without quoting.

This allows you to create SQL for almost any expression, for example EXTRACT( DOY FROM TIMESTAMP "User.creation_date" ), which is a valid Postgres expression. This would be created like this:

  my $term =
      Fey::Literal::Term->new
          ( 'DOY FROM TIMESTAMP ', $column );

  my $function = Fey::Literal::Function->new( 'EXTRACT', $term );

This ability to insert arbitrary strings into a SQL statement is meant to be used as a back-door to support any sort of SQL snippet not otherwise supported by the core Fey classes in a more direct manner.

INHERITANCE ^

This module is a subclass of Fey::Literal.

METHODS ^

This class provides the following methods:

Fey::Literal::Term->new(@fragments)

This method creates a new Fey::Literal::Term object representing the term passed to the constructor.

More than one argument may be given; they will all be joined together in the generated SQL. For example:

  my $term = Fey::Literal::Term->new( $column, '::text' );

The arguments can be plain scalars, objects with a sql_or_alias() method (columns, tables, etc.) or any object which is overloaded (the assumption being it that it overloads stringification).

$term->term()

Returns the array reference of fragments passed to the constructor.

$term->can_have_alias()

$term->set_can_have_alias()

If this attribute is explicitly set to a false value, then then the SQL-generating methods below will never include an alias.

$term->id()

The id for a term is uniquely identifies the term.

$term->sql()

$term->sql_with_alias()

$term->sql_or_alias()

Returns the appropriate SQL snippet. If the term contains any Fey objects, their sql_or_alias() method is called to generate their part of the term.

DETAILS OF SQL GENERATION ^

A term generates SQL by taking each of the elements passed to its constructor and concatenating them. If the element is an object with a sql_or_alias() method, that method will be called to generate SQL. Otherwise, the element is just used as-is.

If $term->can_have_alias() is false, then calling any of the three SQL-generating methods is always equivalent to calling $term->sql().

ROLES ^

This class does the Fey::Role::Selectable, Fey::Role::Comparable, Fey::Role::Groupable, and Fey::Role::Orderable roles.

Of course, the contents of a given term may not really allow for any of these things, but having this class do these roles means you can freely use a term object in any part of a SQL snippet.

BUGS ^

See Fey for details on how to report bugs.

AUTHOR ^

Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE ^

This software is Copyright (c) 2011 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)
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