NAME
Rinci::resmeta - Function/method result metadata
SPECIFICATION VERSION
1.1VERSION
This document describes version 1.1.96 of Rinci::resmeta (from Perl distribution Rinci), released on 2021-01-22.
INTRODUCTION
This document describes metadata for function/method result. This specification is part of Rinci. Please do a read up on it first, if you have not already done so.
SPECIFICATION
There are currently several properties being used:
Properties: cmdline.*
Interpreted by Perinci::CmdLine. See its documentation for more detail.
Properties: content_type
Value: str* (MIME content type)
Can be used to describe the MIME content type of result. Example enveloped result (in Perl):
[200, "OK", "...", {content_type => "image/jpeg"}]See also "Properties: func_content_type.*".
Note: borrowed from HTTP.
Properties: func.* => ANY
These properties allow function to return extra results. Usually done to avoid breaking format of existing result (to maintain API compatibility). The attributes after func. is up to the respective function. An example is the get_args_from_argv() function in the Perinci::Sub::GetArgs::Argv Perl module. The function returns $args but from v0.26 it also wants to give hints about whether or not there are missing arguments. It can do this via func.missing_arg result metadata. Some other examples (in Perl):
# result from check_user()
[200, "OK", 1, # 1 means valie
{
"func.detail" => { # detailed check result
last_login => '2021-01-21T01:55:40Z',
password_secure => 1,
quota_exceeded => 0,
},
}]Properties: func_content_type.*
Value: str* (MIME content type)
Can be used to describe the MIME content type of each extra result. Example (in Perl):
func.attachment => '...',
func_content_type.attachment => 'image/jpeg',See also "Property: content_type".
Property: len
Value: int*
The len, part_start and part_len properties specifies the range of data when function sends partial result. Suppose your function is returning a partial content of a large file where total file size is 24500000 bytes and the returned content is from bytes 10000000 to 15000000, then len is 24500000, part_len is 5000000, and part_start is 10000000. When returning partial content, status will be 206.
Properties: location
Value: str* (URL)
Can be used to specify that the content is elsewhere. Used in combination with 301 or 302 result status. Example (in Perl):
# result from a function that generates a chart
[301, "Moved", undef, {content_type => "image/jpeg", location=>"file:/tmp/asd9uxzw.png"}]Note: borrowed from HTTP.
Property: logs => ARRAY OF HASH
Store log of events happening to this result, stored chronologically (older first). Each log should be a hash which should have at least the following keys: time (Unix timestamp), type (string).
Normally, the first element of the log will contain information about who produced the result and where/when. It has the type key with the value of create. It should be a hash with the following keys:
package => STR
Package (namespace) where this result is produced.
file => STR
File name where the result is created. Might be a relative or absolute path.
line => INT
Line number where the result is created.
func => STR
Function name where this result is produced.
stack_trace => ARRAY
Optional, a stack trace. In Perl this can be produced by using << [caller(1), caller(2), ...] >>.
Property: part_len
Value: int*
See "Property: len"
Property: part_start
Value: int*
See "Property: len".
Property: perm_err => bool
Indicate that error is permanent (instead of temporary/transient). This is to provide a feature like that found in SMTP/POP protocol, where 4xx codes indicate transient errors and 5xx permanent ones.
Property: prev => ARRAY
Store "previous result". Result MUST be enveloped. Usually useful when tracing errors, especially in conjunction with logs: when reporting error that results from a call to another function, the original result can be set here, to preserve information. See Perinci::Sub::Util's err() for a convenience function for this, and Perinci::CmdLine's way of displaying it.
Example:
sub f1 {
...
if (error) { return [500, "Can't f1: blah"] }
...
}
sub f2 {
...
my $res = f1(...);
if ($res is error) { return [500, "Can't f2", undef, {prev=>$res}] }
...
}
sub f3 {
...
my $res = f1(...);
if ($res is error) { return [500, "Can't f3", undef, {prev=>$res}] }
}Property: results => array
When a function returns an error response (in particular status 207, but other statuses can also use this), it can put detailed errors here. For example, a function which processed 5 items wanted to report that 2 items were successfully processed but the rest 3 failed:
[207, "Multistatus", undef, {
results => [
{status=>200, message=>"OK", item_id=>1},
{status=>403, message=>"Forbidden", item_id=>2},
{status=>404, message=>"Not found", item_id=>3},
{status=>500, message=>"Failed", item_id=>4},
{status=>200, message=>"OK", item_id=>5},
],
}]Each result is a hash to be able to store status, message, as well as additional data like item_id or whatever the function wants.
Another example, a function wants to give information on what arguments fail validation:
[400, "Some arguments fail validation", undef, {
results => [
{status=>400, arg=>"name", message=>"Missing"},
{status=>400, arg=>"location/street", message=>"Missing"},
{status=>400, arg=>"age", message=>"Must be numbers only"},
{status=>400, arg=>"password", is_warning=>1,
message=>"Should be longer than 4 characters"}, # warning only
],
}]Property: schema => SCHEMA
Describe result's schema. Has lower precedence than schema from function metadata's result property.
Property: stream => bool
If set to true, signify that result is an output stream. Usually in implementations the result will be a filehandle or an object with getline or getitem methods, where caller can then fetch data from it.
Property: undo_data => ANY
(DEPRECATED) Explained in undo feature section in Rinci::function.
FAQ
HOMEPAGE
Please visit the project's homepage at https://metacpan.org/release/Rinci.
SOURCE
Source repository is at https://github.com/perlancar/perl-Rinci.
BUGS
Please report any bugs or feature requests on the bugtracker website https://github.com/perlancar/perl-Rinci/issues
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.
SEE ALSO
AUTHOR
perlancar <perlancar@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2014, 2013, 2012 by 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.