MooX::Tag::TO_HASH - Controlled translation of Moo objects into Hashes
version 0.06
package My::Farm;
use Moo;
with 'MooX::Tag::TO_HASH';
has cow => ( is => 'ro', to_hash => 1 );
has duck => ( is => 'ro', to_hash => 'goose,if_exists', );
has horse => ( is => 'ro', to_hash => ',if_defined', );
has hen => ( is => 'ro', to_hash => 1, );
has secret_admirer => ( is => 'ro', );
# and somewhere else...
use Data::Dumper;
my $farm = My::Farm->new(
cow => 'Daisy',
duck => 'Frank',
secret_admirer => 'Fluffy',
);
print Dumper $farm->TO_HASH;
# resulting in
$VAR1 = {
'cow' => 'Daisy',
'goose' => 'Frank',
'hen' => undef
};
MooX::Tag::TO_HASH
is a Moo::Role which provides a controlled method of converting your
Moo based object into a hash.
Simply mark each field that should be output with the special option
to_hash
when declaring it:
has field => ( is => 'ro', to_hash => 1 );
and call the "TO_HASH" method on your instantiated object.
my %hash = $obj->TO_HASH;
Fields inherited from superclasses or consumed from roles which use
MooX::Tag::TO_HASH
are automatically handled.
If a field's value is another object, "TO_HASH" will automatically
turn that into a hash if it has its own TO_HASH
method (you can
also prevent that).
[Originally, this module recommended using a method modifier to the TO_HASH method, this is no longer recommended. See discussion under "DEPRECATED BEHAVIOR" below.].
If the class provides a _modify_hashr
method (or for backwards
compatibility, modify_hashr
), it will be called as
$self->_modify_hashr( \%hash );
and should modify the passed hash in place.
Add the to_hash
option to each field which should be
included in the hash. to_hash
can either take a value of 1
,
e.g.
has field => ( is => 'ro', to_hash => 1 );
or a string which looks like one of these:
alternate_name
alternate_name,option_flag,option_flag,...
,option_flag,option_flag,...
If alternate_name
is specified, that'll be the key used in the
output hash.
option_flag
may be one of the following:
if_exists
Only output the field if it was set. This uses "Moo"'s attribute predicate (one will be added to the field if it not already specified).
It will be output if the field is set to undef
.
A synonym for this is omit_if_empty
, for compatibility with
MooX::TO_JSON.
if_defined
Only output the field if it was set and its value is defined.
no_recurse
If a field is an object, don't try and turn it into a hash via its
TO_HASH
method.
(Yes, this name is backwards, but eventually a separate recurse
option may become available which limits the recursion depth).
%hash = $obj->TO_HASH
This method is added to the consuming class or role.
package My::Test::C4;
use Moo;
with 'MooX::Tag::TO_HASH';
has cow => ( is => 'ro', to_hash => 1 );
has duck => ( is => 'ro', to_hash => 'goose,if_exists', );
has horse => ( is => 'ro', to_hash => ',if_defined', );
has hen => ( is => 'ro', to_hash => 1, );
has secret_admirer => ( is => 'ro', );
# upper case the hash keys
sub modify_hashr {
my ( $self, $hashr ) = @_;
$hashr->{ uc $_ } = delete $hashr->{$_} for keys %$hashr;
};
# and elsewhere:
use Data::Dumper;
print Dumper(
My::Test::C4->new(
cow => 'Daisy',
hen => 'Ruby',
duck => 'Donald',
horse => 'Ed',
secret_admirer => 'Nemo'
)->TO_HASH
);
# resulting in
$VAR1 = {
'GOOSE' => 'Donald',
'COW' => 'Daisy',
'HORSE' => 'Ed',
'HEN' => 'Ruby'
};
Previously it was suggested that the around
method modifier be used
to modify the resultant hash. However, if both a child and parent
class consume the MooX::Tag::TO_HASH
role and the parent has
modified TO_HASH
, the parent's modified TO_HASH
will not be run;
instead the original TO_HASH
will. For example
package Role {
use Moo::Role;
sub foo { print "Role\n" }
}
package Parent {
use Moo;
with 'Role';
before 'foo' => sub { print "Parent\n" };
}
package Child {
use Moo;
extends 'Parent';
with 'Role';
before 'foo' => sub { print "Child\n" };
}
Child->new->foo;
results in
Child
Role
Note it does not output Parent
.
Please report any bugs or feature requests to bug-moox-tag-to_[email protected] or through the web interface at: https://rt.cpan.org/Public/Dist/Display.html?Name=MooX-Tag-TO_HASH
Source is available at
https://gitlab.com/djerius/moox-tag-to_hash
and may be cloned from
https://gitlab.com/djerius/moox-tag-to_hash.git
Please see those modules/websites for more information related to this module.
Diab Jerius [email protected]
This software is Copyright (c) 2022 by Smithsonian Astrophysical Observatory.
This is free software, licensed under:
The GNU General Public License, Version 3, June 2007