[librecat-dev] sorting MARC fields

[Uldis Bojars]

On 13 July 2017 at 12:13, Patrick Hochstenbach <
Patrick.Hochstenbach at ugent.be> wrote:

> There is no sorting of MARC fields in the Fix language. One can add fields
> by `marc_add` fixes. The order of the new fields is in the order you
> execute the marc_add commands.
>

I am still trying to understand if sorting is needed (in our use case, at
least):

One place where the MARC spec mention field order is this: "Control fields
precede data fields in the record and are arranged in the same sequence as
the corresponding entries in the directory."

https://www.loc.gov/marc/specifications/specrecstruc.html

If we assume that this is true and control fields should come before data
fields, then adding control fields using 'marc_add' would result on MARC
data that violate this assumption.

A quick fix [to avoid the need for sorting] here would be to allow
inserting new fields before "100" field (= after the last control field).

With the marc_paste (the nephews of marc_copy and marc_cut) you can decide
> where in the record the new marc record should be pasted:
>
>   # Paste mycopy after the last 300 field
>   marc_paste(mycopy, at:300)
>
> https://metacpan.org/pod/Catmandu::Fix::marc_paste


This is a cool feature! :)

What would happen if there are no "300" fields in the record?

In general there is no condition how MARC records could be sorted. Marc
> tags can be repeated:
>
>    500 $aZorro, this is my First note
>    500 $aAlso a nice not, but not the first
>    500 $aWell this is the last note
>
> Sorting the notes will result in errors in the catalogging. MARC is not a
> table or database format but markup language ..
>

Agreed. If sorting were to be implemented it would need to preserve the
order of the existing fields that have the same code.

Uldis


> > On 13 Jul 2017, at 10:25, Uldis Bojars <captsolo at gmail.com> wrote:
> >
> > set_array(ok_fields, FMT, LDR,
> >     008, 040, 041, 075, 100,
> >     240, 245, 246, 260,
> >     377, 380, 388, 400, 490,
> >     600, 630, 650, 670, 677,
> >     700, 720, 908, 910)
> >
> > do marc_each()
> >
> >     copy_field(record.0.0, fld_type)
> >
> >     unless in(fld_type, ok_fields)
> >         remove_field(record)
> >     end
> >
> >     remove_field(fld_type)                  # is this needed?
> >
> > end
> >
> > remove_field(ok_fields)
>
>
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