Rinci::resmeta(3pm)

NAME
Rinci::resmeta - Function/method result metadata

SPECIFICATION VERSION
 1.1

VERSION
This document describes version 1.1.104 of Rinci::resmeta (from Perl distribution Rinci), released on 2023-09-30.

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:

  cmdline.*
Interpreted by Perinci::CmdLine. See its documentation for more detail.

  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.

  func.*
Value: 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,
     },
 }]

  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".

  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.

  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.

  logs
Value: array[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

    Package (namespace) where this result is produced.

•   file

    File name where the result is created. Might be a relative or absolute path.

•   line

    Line number where the result is created.

•   func

    Function name where this result is produced.

•   stack_trace

    Optional, a stack trace. In Perl this can be produced by using << [caller(1), caller(2), ...] >>.

  part_len
Value: int*

See "Property: len"

  part_start
Value: int*

See "Property: len".

  perm_err
Value: 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.

  prev
Value: any

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}] }
 }

  results
Value: 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
      ],
 }]

  schema
Value: sah::schema

Describe result's schema. Has lower precedence than schema from function metadata's result property.

  stream
Value: 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.

  caption
Value: str*

Optional.

  undo_data
Value: 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>.

SEE ALSO
Rinci

AUTHOR
perlancar <perlancar@cpan.org>

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) 2023, 2022, 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2014, 2013, 2012 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=Rinci>

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.