Provided by: libdata-uriencode-perl_0.11-2_all 
NAME
Data::URIEncode - Allow complex data structures to be encoded using flat URIs.
SYNOPSIS
use Data::URIEncode qw(flat_to_complex complex_to_flat);
my $data = {
foo => {
bar => 'bing',
},
baz => [123],
};
my $flat = complex_to_flat($data);
my $query = complex_to_query($data);
# $flat looks like:
$flat = {
'foo.bar' => 'bing',
'baz:0' => 123,
};
# $query looks like:
$query = "foo.bar=bing&baz:0=123"
################################################
# put data back to how it was
$data = flat_to_complex($flat);
$data = query_to_complex($query);
################################################
### some html form somewhere
<form>
<input type="text" name="foo.bar.baz" value="brum">
<input type="text" name="bing:2" value="blang">
<input type="text" name="'key with :, ., and \''.red" value="blue">
</form>
### when the form is submitted to the following code
use CGI;
use Data::URIEncode qw(query_to_complex);
my $q = CGI->new;
my $data = query_to_complex($q);
### data will look like
$data = {
foo => {
bar => {
baz = "brum",
},
},
bing => [
undef,
undef,
"blang",
],
"key with :, ., and '" => {
red = "blue",
},
};
DESCRIPTION
The world of the web works off of URI's. The Query string portion of URIs already support
encoding of key/value paired data - they just don't natively allow for for complex data
structures.
There are modules or encodings that do support arbitrarily complex data structures. JSON,
YAML and Data::Dumper all have their own way of encoding complex structures. But then to
pass them across the web, you usually still have to URL encode them and pass them via a
form parameter.
Data::URIEncode allows for encoding and decoding complex (multi level datastructures)
using native Query String manipulators (such as CGI.pm). It takes complex data and turns
it into a flat hashref which can then be turned into a URI query string using URL
encoding. It also takes a flat hashref of data passed in and translates it back to a
complex structure.
One benefit of using Data::URIEncode is that a standard submission from a standard html
form can automatically be translated into complex data even though it arrived in a "flat"
form. This somewhat mimics the abilities of XForms without introducing the complexity of
XForms.
Another benefit is that sparse data can be represented in a more compact form than JSON or
YAML are able to provide. However, complex data with long key names will be more verbose
as the full data hierarchy must be repeated for each value.
RULES
For each of the following rules, the $data can be translated to $flat and $query by
calling complex_to_flat and complex_to_query respectively. The $flat and $query can be
translated back into $data using flat_to_complex and query_to_complex respectively.
Simple values stay simple
$data = {key => "val", key2 => "val2"};
$flat === {key => "val", key2 => "val2"};
$query eq "key=val&key2=val2"
Nested hashes use a dot to modify the key.
$data = {key => {key2 => "val"}};
$flat === {"key.key2" => "val"};
$query eq "key.key2=val
########
$data = {foo => {bar => {baz => "bling"}}};
$flat === {"foo.bar.baz" = "bling"};
$query eq "foo.bar.baz=bling"
Nested arrays use a colon to modify the key.
$data = {key => ["val1", "val2"]};
$flat === {"key:0" => "val1", "key:1" => "val2"};
$query eq "key:0=val1&key:1=val2"
########
$data = {key => [ [ ["val"] ] ]};
$flat === {"key:0:0" => "val"}
$query eq "key:0:0=val"
Data structures can have an arrayref as the top level
A leading colon is used to indicate the top level node is an arrayref.
$data = ["val1", "val2"]
$flat === {":0" => "val1", ":1" => "val2"}
$query eq ":0=>val1&:1=>val2"
########
$data = [ [ ["val"] ] ];
$flat === {":0:0:0" => "val"}
$query eq ":0:0:0=val"
Keys in flat hashrefs MAY begin with a leading dot
A leading dot may disambiguate some cases.
$query = ".foo=bar"
$flat = {".foo" => "bar"}
$data === {foo => "bar"}
Single quotes may be used to enclose complex strings.
Any key containing a colon ":", a dot ".", or a single quote "'" must be quoted with
single quotes and have enclosed single quotes escaped.
$data = {"foo.bar" => "baz"}
$flat === {"'foo.bar'" => "baz"}
$query eq "'foo.bar'=baz" # the ' will be swapped with %27
########
$data = {"foo:bar" => "baz"}
$flat === {"'foo:bar'" => "baz"}
$query eq "'foo:bar'=baz" # the ' will be swapped with %27
########
$data = {"" => "baz"}
$flat === {"''" => "baz"}
$query eq "''=baz" # the ' will be swapped with %27
########
$data = {"'" => "baz"}
$flat === {"'\\''" => "baz"}
$query eq "'\\''=baz" # the ' will be swapped with %27 and the \ will be replaced with %5C
Single quotes were chosen as double quotes are most commonly used in HTML forms, thus
allowing escaped single quotes more easily inside the double quoted name.
Undefined values are not included in the flattened data
$data = {foo => undef, bar => 1}
$flat === {bar => 1}
$query eq "bar=1"
########
$data = ["val1", undef, "val2"]
$flat === {":0" => "val1", ":2" => "val2"}
$query eq ":0=val1&:2=val2"
Blessed hashes and arrayrefs are dumped by default.
Changing the default value of the global $DUMP_BLESSED_DATA variable changes the
behavior.
$Data::URIEncode::DUMP_BLESSED_DATA = 1; # default
$data = {foo => bless({bar => "baz"}, "main"), one => "two"}
$flat === {"foo.bar" => "baz", one => "two"}
$query eq "foo.bar=baz&one=two"
########
$Data::URIEncode::DUMP_BLESSED_DATA = 0;
$data = {foo => bless({bar => "baz"}, "main"), one => "two"}
$flat === {one => "two"}
$query eq "one=two"
Arrays created by flat_to_complex and query_to_complex must obey the value of the
$MAX_ARRAY_EXPAND variable.
FUNCTIONS
flat_to_complex
Takes a hashref of simple key value pairs. Returns a data structure based on the the
parsed key value pairs. The parsing proceeds according to the rules listed in RULES.
my $data = flat_to_complex({"foo.bar.baz:2" => "bling"});
# $data = {foo => {bar => {baz => [undef, undef, "bling"]}}};
complex_to_flat
Takes a complex data structure and turns it into a flat hashref (single level
key/value pairs only). The parsing proceeds according to the rules listed in RULES.
my $flat = complex_to_flat({foo => ['a','b']});
# $flat = {"foo:0" => "a", "foo:1" => "b"});
complex_to_query
Similar to complex_to_flat, except that the flattened hashref is then translated into
query string suitable for use in a URI.
my $str = complex_to_query({foo => ['a','b']});
# $str eq "foo:0=a&foo:1=b"
query_to_complex
Takes one of a string, a reference to a string, a hash, or a CGI.pm compatible object
and translates it into a complex data structure. Similar to flat_to_complex, exempt
that a first step is taken to access the query parameters from the CGI compatible
object or string. If a string or string ref is given, the CGI module is used to parse
the string into an initial flat hash of key value pairs (using the param method). If
another module is desired over, CGI.pm you must initialize it with the data to be
parsed prior to passing the object to the query_to_complex function.
my $data = query_to_complex("foo.bar:0=baz");
my $data = query_to_complex(\ "foo.bar:0=baz");
my $data = query_to_complex({"foo.bar:0" => "baz"}); # same as flat_to_complex
my $cgi = CGI->new(\ "foo.bar:0=baz");
my $data = query_to_complex($cgi);
my $cgi = CGI->new; # use the values passed in from STDIN
my $data = query_to_complex($cgi);
VARIABLES
$MAX_ARRAY_EXPAND
Default value is 100. This variable is used to determine how large flat_to_complex
will allow an array to be expanded beyond its current size. An array can grow as
large as you have memory, but intermediate values must exist.
Without this value, somebody could specify foo:1000000000000=bar and your server would
attempt to set the 1000000000000th index of the foo value to bar.
The string "foo:101=bar" would die, but the string "foo:50=bar&foo:101=baz" would not
die because the intermediate foo->[50] increments the foo arrayref by 51 and the
subsequent foo->[101] call increments the foo arrayref by only 51.
$DUMP_BLESSED_DATA
Default is true. If true, blessed hashrefs and arrayrefs will also be added to the
flat data returned by complex_to_flat. If false, bless hashrefs and arrayrefs will be
skipped.
BUGS
Circular refs are not detected. Any attempt to dump a struture with cirular refs will
result in an infinite loop. There is no immediate plan to add circular ref tracking.
SEE ALSO
All of the following have attempted to solve the same problem as Data::URIEncode. All of
them (including Data::URIEncode) suffer from the problem of being hard to find for the
specific purpose. Hash::Flatten is probably the only suitable replacement for
Data::URIEncode.
Hash::Flatten
CGI::Expand
HTTP::Rollup
CGI::State
AUTHOR
Paul Seamons perlspam at seamons dot com
LICENSE
This library may be distributed under the same terms as Perl itself.