Modifying metadata elements with Lua filter

Modifying metadata elements with Lua filter

[Stephan Boltzmann]

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Hello everybody out there using Pandoc,

For the following short document,
---
title: Test
author:
  - Author A
  - Author B
---
# Introduction

I would expect the Lua filter

function Meta (m)
    print(pandoc.utils.stringify(m.author[1].MetaInlines[2]))
end

to print out "A", but it prints nothing at all.

What is the conceptual misunderstanding I have here?

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Re: Modifying metadata elements with Lua filter

['William Lupton' via pandoc-discuss]

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Your metadata has this structure (hmm... perhaps some of the Inlines are
really MetaInlines, in which case that's a problem with my logging module):

(#) meta Meta {
  author: List[2] {
    [1] Inlines[3] {
      [1] Str "Author"
      [2] Space
      [3] Str "A"
    }
    [2] Inlines[3] {
      [1] Str "Author"
      [2] Space
      [3] Str "B"
    }
  }
  title: Inlines[1] {
    [1] Str "Test"
  }
}

... so I think you want this filter (MetaInlines isn't an attribute name,
and you have to count the space):

function Meta (m)
    print(pandoc.utils.stringify(m.author[1][3]))
end

On Wed, 14 Jun 2023 at 17:47, Stephan Boltzmann <stephan2boltzmann-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:

> Hello everybody out there using Pandoc,
>
> For the following short document,
> ---
> title: Test
> author:
>   - Author A
>   - Author B
> ---
> # Introduction
>
> I would expect the Lua filter
>
> function Meta (m)
>     print(pandoc.utils.stringify(m.author[1].MetaInlines[2]))
> end
>
> to print out "A", but it prints nothing at all.
>
> What is the conceptual misunderstanding I have here?
>
> --
> You received this message because you are subscribed to the Google Groups
> "pandoc-discuss" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to pandoc-discuss+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com
> <https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>

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Re: Modifying metadata elements with Lua filter

[Stephan Boltzmann]

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Thanks a lot for your help, which enabled me to write the following short 
filter, which puts the name of all authors on the same line in 'docx' 
output, while preserving the nice default layout in 'latex' output.
Debugging filters working on the yaml metadata provided a particular 
challenge to me:

function Meta (m)
  if FORMAT:match 'docx' then
        authors = m.author[1] .. {pandoc.Str(', ')} .. m.author[2]
        m.author = pandoc.MetaInlines(authors)
  end
  return m
end

It only handles two and not more authors, but in my case, that's fine.
William Lupton schrieb am Mittwoch, 14. Juni 2023 um 18:55:04 UTC+2:

> Your metadata has this structure (hmm... perhaps some of the Inlines are 
> really MetaInlines, in which case that's a problem with my logging module):
>
> (#) meta Meta {
>   author: List[2] {
>     [1] Inlines[3] {
>       [1] Str "Author"
>       [2] Space
>       [3] Str "A"
>     }
>     [2] Inlines[3] {
>       [1] Str "Author"
>       [2] Space
>       [3] Str "B"
>     }
>   }
>   title: Inlines[1] {
>     [1] Str "Test"
>   }
> }
>
> ... so I think you want this filter (MetaInlines isn't an attribute name, 
> and you have to count the space):
>
> function Meta (m)
>     print(pandoc.utils.stringify(m.author[1][3]))
> end
>
> On Wed, 14 Jun 2023 at 17:47, Stephan Boltzmann <stephan2...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 
> wrote:
>
>> Hello everybody out there using Pandoc,
>>
>> For the following short document,
>> ---
>> title: Test
>> author:
>>   - Author A
>>   - Author B
>> ---
>> # Introduction
>>
>> I would expect the Lua filter
>>
>> function Meta (m)
>>     print(pandoc.utils.stringify(m.author[1].MetaInlines[2]))
>> end
>>
>> to print out "A", but it prints nothing at all.
>>
>> What is the conceptual misunderstanding I have here?
>>
>> -- 
>> You received this message because you are subscribed to the Google Groups 
>> "pandoc-discuss" group.
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to pandoc-discus...-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com 
>> <https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com?utm_medium=email&utm_source=footer>
>> .
>>
>

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Re: Modifying metadata elements with Lua filter

[BPJ]

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It is better to not hard code the number of authors:

``````lua
function Meta (meta)
  if 'docx' == FORMAT then
    if 'List' ~= pandoc.utils.type(meta.author) then
      -- hopefully Inlines
      return nil
    elseif 1 == #meta.author then -- only one
      meta.author = meta.author[1]
    else -- more than one
      -- Define once, use many times
      local sep = pandoc.Inlines(", ") -- DWIM
      -- Initialize to an empty list and use `:extend` to populate
      local authors = pandoc.Inlines({ })
      -- Loop through any number of authors
      for i, author in ipairs(meta.author) do
        if 1 == i then -- no comma for the first
          authors:extend(author)
        else -- append ", A. U. Thor"
          authors:extend(sep .. author)
        end
      end
      -- Put them back
      meta.author = authors
      -- We have modified, so return it
      return meta
    end
  end
  return nil -- nothing modified
end
``````

Den tors 15 juni 2023 17:18Stephan Boltzmann <stephan2boltzmann-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
skrev:

> Thanks a lot for your help, which enabled me to write the following short
> filter, which puts the name of all authors on the same line in 'docx'
> output, while preserving the nice default layout in 'latex' output.
> Debugging filters working on the yaml metadata provided a particular
> challenge to me:
>
> function Meta (m)
>   if FORMAT:match 'docx' then
>         authors = m.author[1] .. {pandoc.Str(', ')} .. m.author[2]
>         m.author = pandoc.MetaInlines(authors)
>   end
>   return m
> end
>
> It only handles two and not more authors, but in my case, that's fine.
> William Lupton schrieb am Mittwoch, 14. Juni 2023 um 18:55:04 UTC+2:
>
>> Your metadata has this structure (hmm... perhaps some of the Inlines are
>> really MetaInlines, in which case that's a problem with my logging module):
>>
>> (#) meta Meta {
>>   author: List[2] {
>>     [1] Inlines[3] {
>>       [1] Str "Author"
>>       [2] Space
>>       [3] Str "A"
>>     }
>>     [2] Inlines[3] {
>>       [1] Str "Author"
>>       [2] Space
>>       [3] Str "B"
>>     }
>>   }
>>   title: Inlines[1] {
>>     [1] Str "Test"
>>   }
>> }
>>
>> ... so I think you want this filter (MetaInlines isn't an attribute name,
>> and you have to count the space):
>>
>> function Meta (m)
>>     print(pandoc.utils.stringify(m.author[1][3]))
>> end
>>
>> On Wed, 14 Jun 2023 at 17:47, Stephan Boltzmann <stephan2...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> wrote:
>>
>>> Hello everybody out there using Pandoc,
>>>
>>> For the following short document,
>>> ---
>>> title: Test
>>> author:
>>>   - Author A
>>>   - Author B
>>> ---
>>> # Introduction
>>>
>>> I would expect the Lua filter
>>>
>>> function Meta (m)
>>>     print(pandoc.utils.stringify(m.author[1].MetaInlines[2]))
>>> end
>>>
>>> to print out "A", but it prints nothing at all.
>>>
>>> What is the conceptual misunderstanding I have here?
>>>
>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "pandoc-discuss" group.
>>> To unsubscribe from this group and stop receiving emails from it, send
>>> an email to pandoc-discus...-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> To view this discussion on the web visit
>>> https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com
>>> <https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com?utm_medium=email&utm_source=footer>
>>> .
>>>
>> --
> You received this message because you are subscribed to the Google Groups
> "pandoc-discuss" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to pandoc-discuss+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/pandoc-discuss/64f0f40b-5c49-47fa-97f5-f824735f6cebn%40googlegroups.com
> <https://groups.google.com/d/msgid/pandoc-discuss/64f0f40b-5c49-47fa-97f5-f824735f6cebn%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>

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Re: Modifying metadata elements with Lua filter

[Stephan Boltzmann]

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Thanks a lot for your solution.
With your help and the logging module, programming Lua filters for Pandoc 
is starting to be fun and I came up with this solution by myself:

function Meta (m)
  if FORMAT:match 'docx' then
    authors = pandoc.List:new()
    for i, author in ipairs(m.author) do
      if m.author[i] then
        authors = authors .. author .. {pandoc.Str(', ')}
      else
        authors = authors .. author
      end
    end
    m.author = pandoc.MetaInlines(authors)
  end
  return m
end


BPJ schrieb am Donnerstag, 15. Juni 2023 um 18:35:18 UTC+2:

> It is better to not hard code the number of authors:
>
> ``````lua
> function Meta (meta)
>   if 'docx' == FORMAT then
>     if 'List' ~= pandoc.utils.type(meta.author) then
>       -- hopefully Inlines
>       return nil
>     elseif 1 == #meta.author then -- only one
>       meta.author = meta.author[1]
>     else -- more than one
>       -- Define once, use many times
>       local sep = pandoc.Inlines(", ") -- DWIM
>       -- Initialize to an empty list and use `:extend` to populate
>       local authors = pandoc.Inlines({ })
>       -- Loop through any number of authors
>       for i, author in ipairs(meta.author) do
>         if 1 == i then -- no comma for the first
>           authors:extend(author)
>         else -- append ", A. U. Thor"
>           authors:extend(sep .. author)
>         end
>       end
>       -- Put them back
>       meta.author = authors
>       -- We have modified, so return it
>       return meta
>     end
>   end
>   return nil -- nothing modified
> end
> ``````
>
> Den tors 15 juni 2023 17:18Stephan Boltzmann <stephan2...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 
> skrev:
>
>> Thanks a lot for your help, which enabled me to write the following short 
>> filter, which puts the name of all authors on the same line in 'docx' 
>> output, while preserving the nice default layout in 'latex' output.
>> Debugging filters working on the yaml metadata provided a particular 
>> challenge to me:
>>
>> function Meta (m)
>>   if FORMAT:match 'docx' then
>>         authors = m.author[1] .. {pandoc.Str(', ')} .. m.author[2]
>>         m.author = pandoc.MetaInlines(authors)
>>   end
>>   return m
>> end
>>
>> It only handles two and not more authors, but in my case, that's fine.
>> William Lupton schrieb am Mittwoch, 14. Juni 2023 um 18:55:04 UTC+2:
>>
>>> Your metadata has this structure (hmm... perhaps some of the Inlines are 
>>> really MetaInlines, in which case that's a problem with my logging module):
>>>
>>> (#) meta Meta {
>>>   author: List[2] {
>>>     [1] Inlines[3] {
>>>       [1] Str "Author"
>>>       [2] Space
>>>       [3] Str "A"
>>>     }
>>>     [2] Inlines[3] {
>>>       [1] Str "Author"
>>>       [2] Space
>>>       [3] Str "B"
>>>     }
>>>   }
>>>   title: Inlines[1] {
>>>     [1] Str "Test"
>>>   }
>>> }
>>>
>>> ... so I think you want this filter (MetaInlines isn't an attribute 
>>> name, and you have to count the space):
>>>
>>> function Meta (m)
>>>     print(pandoc.utils.stringify(m.author[1][3]))
>>> end
>>>
>>> On Wed, 14 Jun 2023 at 17:47, Stephan Boltzmann <stephan2...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 
>>> wrote:
>>>
>>>> Hello everybody out there using Pandoc,
>>>>
>>>> For the following short document,
>>>> ---
>>>> title: Test
>>>> author:
>>>>   - Author A
>>>>   - Author B
>>>> ---
>>>> # Introduction
>>>>
>>>> I would expect the Lua filter
>>>>
>>>> function Meta (m)
>>>>     print(pandoc.utils.stringify(m.author[1].MetaInlines[2]))
>>>> end
>>>>
>>>> to print out "A", but it prints nothing at all.
>>>>
>>>> What is the conceptual misunderstanding I have here?
>>>>
>>>> -- 
>>>> You received this message because you are subscribed to the Google 
>>>> Groups "pandoc-discuss" group.
>>>> To unsubscribe from this group and stop receiving emails from it, send 
>>>> an email to pandoc-discus...-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>>> To view this discussion on the web visit 
>>>> https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com 
>>>> <https://groups.google.com/d/msgid/pandoc-discuss/19962c60-238b-4ef4-bad6-a8200ca9a3cen%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>> .
>>>>
>>> -- 
>> You received this message because you are subscribed to the Google Groups 
>> "pandoc-discuss" group.
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to pandoc-discus...-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>
> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/pandoc-discuss/64f0f40b-5c49-47fa-97f5-f824735f6cebn%40googlegroups.com 
>> <https://groups.google.com/d/msgid/pandoc-discuss/64f0f40b-5c49-47fa-97f5-f824735f6cebn%40googlegroups.com?utm_medium=email&utm_source=footer>
>> .
>>
>

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