/ 
Rinci-1.1.99
River stage one • 1 direct dependent • 1 total dependent
/ Rinci::resmeta

NAME

Rinci::resmeta - Function/method result metadata

SPECIFICATION VERSION

1.1

VERSION

This document describes version 1.1.99 of Rinci::resmeta (from Perl distribution Rinci), released on 2021-12-09.

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.

title

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, and sometimes one or two other Dist::Zilla plugin and/or Pod::Weaver::Plugin. Any additional steps required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE

This software is copyright (c) 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.