NAME Data::Transmute - Transmute (transform) data structure using rules data VERSION This document describes version 0.040 of Data::Transmute (from Perl distribution Data-Transmute), released on 2024-07-17. SYNOPSIS use Data::Transmute qw( transmute_data reverse_rules ); my $transmuted_data = transmute_data( data => \@data, rules => [ # CREATING HASH KEY # this rule only applies when data is a hash, when data is not a hash # this will do nothing. create a single new hash key, error if key # already exists. [create_hash_key => {name=>'foo', value=>1}], # create another hash key, but this time ignore/noop if key already # exists (ignore=1). this is like INSERT IGNORE in SQL. note: this # makes the rule irreversible. [create_hash_key => {name=>'bar', value=>2, ignore=>1}], # create yet another key, this time replace existing keys (replace=1). # this is like REPLACE INTO in SQL. note: this makes the rule # irreversible. [create_hash_key => {name=>'baz', value=>3, replace=>1}], # compute value with coderef (supply 'value_code' instead of 'value'). # note: this makes the rule irreversible. [create_hash_key => {name=>'baz', value_code=>sub {uc($_[0]}, replace=>1}], # RENAMING HASH KEY # this rule only applies when data is a hash, when data is not a hash # this will do nothing. rename a single key, error if old name doesn't # exist or new name exists. [rename_hash_key => {from=>'qux', to=>'quux'}], # rename another key, but this time ignore if old name doesn't exist # (ignore=1) or if new name already exists (replace=1) [rename_hash_key => {from=>'corge', to=>'grault', ignore_missing_from=>1, replace=>1}], # MODIFYING HASH VALUE # this rule only applies when data is a hash, when data is not a hash # this will do nothing. change the value of a single keypair (key # specified in 'name'), error if key doesn't exist or old value doesn't # equal specified ('from'). [modify_hash_value => {name=>'foo', from=>'old', to=>'new'}], # 'from' is optional, but if you omit it, the rule becomes # irreversible. [modify_hash_value => {name=>'foo', to=>'new'}], # instead of specifying new value in 'to', you can compute new value # using 'to_code'. note: if you do this the rule becomes irreversible. [modify_hash_value => {name=>'foo', from_old=>'old', to_code=>sub {uc $_[0]}}], # DELETING HASH KEY # this rule only applies when data is a hash, when data is not a hash # this will do nothing. delete a single key, will noop if key already # doesn't exist. [delete_hash_key => {name=>'garply'}], # APPLYING (SUB)RULES TO ARRAY ELEMENTS # this rule only applies when data is an arrayref, when data is not an # array this will do nothing. for each array element, apply transmute # rules to it. [transmute_array_elems => { rules => [...], # or 'rules_module' }], # you can select only certain elements to transmute by using one+ of: # index_is, index_in, index_match, index_filter. [transmute_array_elems => { rules => [...], # or 'rules_module' #index_is => 1, # only transmute 2nd element (index is 0-based) #index_in => [0,1,2], # only transmute the first 3 elements #index_match => qr/.../, # only transmute elements where the index matches a regex #index_filter => sub{...}, # only transmute elements where $filter->(index=>$index) returns true }], # APPLYING (SUB)RULES TO HASH VALUES # this rule only applies when data is a hashref, when data is not a # hash this will do nothing. for each hash value, apply transmute rules # to it. [transmute_hash_values => { rules => [...], # or 'rules_module' }], # you can select only certain keys to transmute by using one+ of: # key_is, key_in, key_match, key_filter. [transmute_hash_values => { rules => [...], # or 'rules_module' #key_is => 'foo', # only transmute value of key 'foo' #key_in => ['foo', 'bar'], # only transmute value of keys 'foo', 'bar' #key_match => qr/.../, # only transmute value of keys that match a regex #key_filter => sub{...}, # only transmute value of keys where $filter->(key=>$key) returns true }], # APPLYING (SUB)RULES TO NODES # this rule will transmute data, then recurse (walk) to array elements # (if data is an array) and hash values (if data is a hash). can handle # circular references. this rule is irreversible. [transmute_nodes => { rules => [...], # or 'rules_module' }], ], ); You can also load rules from a "Data::Transmute::Rules::*" module: transmute_data( data => $data, rules_module => 'Convert_Proj1_Data_To_Proj2', # will load Data::Transmute::Rules::Convert_Proj1_Data_To_Proj2 and read its @RULES package variable ); DESCRIPTION This module provides routines to transmute (transform) a data structure in-place using rules which is another data structure (an arrayref of rule specifications). One use-case for this module is to convert/upgrade configuration files. RULES Rules is an array of rule specifications. Each rule specification: [$funcname, \%args] \%args: a special arg will be inserted: "data". create_hash_key This rule only applies when data is a hash, when data is not a hash this will do nothing. Create a single new hash key, error if key already exists. Known arguments ("*" means required): * name* * value Either "value" or "value_code" is required. * value_code Either "value" or "value_code" is required. Instead of specifying value, you can also supply a coderef to compute the value. The coderef will be passed the current value of the hash key (or undef if there is none). If you supply "value_code", your rule will become irreversible. * ignore Bool. If set to true, will ignore/noop if key already exists. This is like INSERT IGNORE (INSERT OR IGNORE) in SQL. If you set "ignore" to true, your rule will become irreversible. * replace Bool. If set to true, will replace existing keys. This is like REPLACE INTO in SQL. If you set "replace" to true, your rule will become irreversible. * transmute_object Bool, default true. By default, blessed hash is also transmuted. But if you set this to false, blessed hash will not be touched. rename_hash_key This rule only applies when data is a hash, when data is not a hash this will do nothing. Rename a single key, error if old name doesn't exist or new name exists. Known arguments ("*" means required): * from* * to* * ignore_missing_from Bool. If set to true, will noop (instead of error) if old name doesn't exist. * replace Bool. If set to true, will overwrite (instead of error) when target key already exists. * transmute_object Bool, default true. By default, blessed hash is also transmuted. But if you set this to false, blessed hash will not be touched. modify_hash_value This rule only applies when data is a hash, when data is not a hash this will do nothing. Modify a single hash value from original value *from* to new value *to*. Key must exist, and value must originally be *from*. Known arguments ("*" means required): * name* String. Key name. * from* String or undef. Original value. * to String or undef. New value. Either "to" or "to_code" is required. * to_code Coderef. Instead of specifying new vlaue via "to", you can also supply "to_code" (a coderef) to compute the value. The coderef will be passed the current value. If you set "to_code", your rule will become irreversible. * transmute_object Bool, default true. By default, blessed hash is also transmuted. But if you set this to false, blessed hash will not be touched. delete_hash_key This rule only applies when data is a hash, when data is not a hash this will do nothing. Delete a single key, will noop if key already doesn't exist. Known arguments ("*" means required): * name* * transmute_object Bool, default true. By default, blessed hash is also transmuted. But if you set this to false, blessed hash will not be touched. transmute_array_elems This rule only applies when data is an arrayref, when data is not an array this will do nothing. for each array element, apply transmute rules to it. Known arguments ("*" means required): * rules Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". * rules_module Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". * index_is * index_in * index_match * index_filter Coderef. Only transmute elements where $coderef->(index=>$index) is true. Aside from "index", the coderef will also receive these arguments: "rules" (the rule), "array" (the array). * transmute_object Bool, default true. By default, blessed array is also transmuted. But if you set this to false, blessed array will not be touched. transmute_hash_values This rule only applies when data is a hashref, when data is not a hash this will do nothing. For each hash value, apply transmute rules to it. Known arguments ("*" means required): * rules Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". * rules_module Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". * key_is * key_in * key_match * key_filter Coderef. Only transmute value of keys where $coderef->(key=>$key) is true. Aside from "key", the coderef will also receive these arguments: "rules" (the rule), "hash" (the hash). * transmute_object Bool, default true. By default, blessed hash is also transmuted. But if you set this to false, blessed hash will not be touched. transmute_nodes This rule will transmute data, then recurse (walk) to array elements (if data is an array) or hash values (if data is a hash) and transmute each of those child data. Can handle circular references. This rule is not irreversible. Known arguments ("*" means required): * recurse_object Boolean, default false. Whether to recurse into (hash-based and array-based) objects. By default, objects are not recursed. Set this to true to recurse into objects. * rules Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". * rules_module Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". FUNCTIONS transmute_data Usage: $data = transmute_data(%args) Transmute data structure, die on failure. Input data is specified in the "data" argument, which will be modified in-place (so you'll need to clone it first if you don't want to modify the original data). Rules is specified in "rules" argument. Known arguments ("*" means required): * data* * rules Array of rules. See "RULES" for more details. Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". * rules_module Specify name of module (without the "Data::Transmute::Rules::" prefix) which contains the actual rules. The module will be loaded and the rules retrieved from its @RULES package variable. Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". reverse_rules Usage: my $reverse_rules = reverse_rules(rules => [...]); Create a reverse of rules, die on failure. For example, this set of rules: [ [create_hash_key => {name=>'a', value=>1}], [rename_hash_key => {from=>'c', to=>'d'}], ] when reversed will become: [ [rename_hash_key => {from=>'d', to=>'c'}], [delete_hash_key => {name=>'a'}], ] Some rules cannot be reversed, e.g. "delete_hash_key" so when given rules that contain that, the function will die. A rule can only be reversed for a subset of arguments, e.g. "rename_hash_key" with "ignore" set to true or "replace" set to true cannot be reversed. The reverse of a set of rules can be used to reverse back a transmuted data back to the original. Known arguments ("*" means required): * rules Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". See "transmute_data" for more details. * rules_module Either "rules" or "rules_module" is required. "rules" takes precedence over "rules_module". See "transmute_data" for more details. ENVIRONMENT LOG_DATA_TRANSMUTE_STEP Boolean. If set to true, will log each transmute step (rule by rule) at the trace level using Log::ger. TODOS Function to mass rename keys (by regex substitution, prefix, custom Perl code, ...). But this cannot produce reverse of rule. Function to mass delete keys (by regex, prefix, ...). But this cannot produce reverse of rule. HOMEPAGE Please visit the project's homepage at <https://metacpan.org/release/Data-Transmute>. SOURCE Source repository is at <https://github.com/perlancar/perl-Data-Transmute>. SEE ALSO Hash::Transform is similar in concept. It allows transforming a hash using rules encoded in a hash. However, the rules only allow for simpler transformations: rename a key, create a key with a specified value, create a key that from a string-based join of other keys/strings. For more complex needs, you'll have to supply a coderef to do the transformation yourself manually. Another thing I find limiting is that the rules is a hash, which means there is no way to specify order of processing. And of course, you cannot transform non-hash data. Config::Model, which you can also use to convert/upgrade configuration files. But I find this module slightly too heavyweight for the simpler needs that I have, hence I created Data::Transmute. Bencher::Scenarios::DataTransmute AUTHOR perlancar <perlancar@cpan.org> CONTRIBUTOR Steven Haryanto <stevenharyanto@gmail.com> CONTRIBUTING To contribute, you can send patches by email/via RT, or send pull requests on GitHub. Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via: % prove -l If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps required beyond that are considered a bug and can be reported to me. COPYRIGHT AND LICENSE This software is copyright (c) 2024, 2020, 2019, 2015 by perlancar <perlancar@cpan.org>. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. BUGS Please report any bugs or feature requests on the bugtracker website <https://rt.cpan.org/Public/Dist/Display.html?Name=Data-Transmute> When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.