Bulk delete custom metadata inside epubs

[senhal]

I've got a library with 4000+ books. There are 2 (useless) custom columns which have generate metadata inside epub and opf files:

<meta name="calibre:user_metadata:#formats" content="{&quot;column&quot;: &quot;value&quot;, &quot;datatype&quot;: &quot;composite&quot;, &quot;rec_index&quot;: 22, &quot;search_terms&quot;: [&quot;#formats&quot;], &quot;colnum&quot;: 1, &quot;kind&quot;: &quot;field&quot;, &quot;is_multiple2&quot;: {}, &quot;category_sort&quot;: &quot;value&quot;, &quot;is_csp&quot;: false, &quot;is_editable&quot;: true, &quot;table&quot;: &quot;custom_column_1&quot;, &quot;#extra#&quot;: null, &quot;display&quot;: {&quot;composite_template&quot;: &quot;{:'approximate_formats()'}&quot;, &quot;make_category&quot;: true, &quot;use_decorations&quot;: 2, &quot;contains_html&quot;: true, &quot;composite_sort&quot;: &quot;text&quot;, &quot;description&quot;: &quot;&quot;}, &quot;link_column&quot;: &quot;value&quot;, &quot;label&quot;: &quot;formats&quot;, &quot;is_category&quot;: false, &quot;is_multiple&quot;: null, &quot;is_custom&quot;: true, &quot;name&quot;: &quot;Formati&quot;, &quot;#value#&quot;: &quot;EPUB&quot;}"/>

I tried to delete the columns from Calibre library, but metadatas remain - the same happens if I export books.
Is it possible to bulk remove them?

[eschwartz]

Exporting them will simply re-add all custom metadata from your current custom columns.

But see the plugin "EPUB Modify", which has an option to delete non-Dublin Core metadata from selected books.

[senhal]

Originally Posted by eschwartz

But see the plugin "EPUB Modify", which has an option to delete non-Dublin Core metadata from selected books.

Perfect, thanks!

[senhal]

Originally Posted by eschwartz

But see the plugin "EPUB Modify", which has an option to delete non-Dublin Core metadata from selected books.

At the end, I find that this method has some undesired side-effects.
Is there a plugin which allows me to apply a regex to all the epubs in my library?
Thanks.

[eschwartz]

If there was one it would not be programmed to affect the content.opf

In what way does EPUB Modify have undesired side effects?

[jackie_w]

Originally Posted by eschwartz

If there was one it would not be programmed to affect the content.opf

In what way does EPUB Modify have undesired side effects?

Possibly because Modify Epub Delete non-Dublin Core metadata would also delete useful stuff such as calibre Series/index metadata???

[senhal]

Originally Posted by eschwartz

If there was one it would not be programmed to affect the content.opf

In what way does EPUB Modify have undesired side effects?

I usually write personal comments in opf...
Also the cover metadata is lost:

<meta name="cover" content="cover"/>

Is it useless?
I noticed, for example, that converting via kindle previewer an epub without this metadata, a warning says no cover is found.

[theducks]

Originally Posted by senhal

I usually write personal comments in opf...
Also the cover metadata is lost:

<meta name="cover" content="cover"/>

Is it useless?
I noticed, for example, that converting via kindle previewer an epub without this metadata, a warning says no cover is found.

Cover has 2 parts to be valid
The HTML page and the IMAGE.

If either has issues, Not Found

Calibre and Sigil cover tools always create both entries

[eschwartz]

Originally Posted by jackie_w

Possibly because Modify Epub Delete non-Dublin Core metadata would also delete useful stuff such as calibre Series/index metadata???

Originally Posted by senhal

I usually write personal comments in opf...
Also the cover metadata is lost:

<meta name="cover" content="cover"/>

Is it useless?
I noticed, for example, that converting via kindle previewer an epub without this metadata, a warning says no cover is found.

All three of those things should IMHO be kept, in fact I have thought about the first two before.

As for comments, maybe there are better ways to keep notes about the book, don't abuse the OPF.

Keep an eye on the Modify EPUB thread.