To start, make sure you've read through Adding Items to Zotero.

In Zotero, you almost never create items manually. You generally save them from the web using the Zotero Connector, and Zotero downloads the metadata and, when possible, the PDF automatically. Alternatively, if you add an OCRed PDF directly and it has a DOI or ISBN in the first few pages, Zotero can retrieve metadata for it, and it can also extract limited metadata for PDFs without identifiers. Finally, you can enter a DOI or ISBN into Add Item by Identifier in the Zotero toolbar to retrieve metadata that way.

We're working on the ability to update existing items, but that's more for updating previously saved preprint items and not really related to adding items to Zotero initially.

When you have a PDF already, you can certainly drag it in, and Zotero can often retrieve metadata for it. But that only works when the file is OCRed, and it works best when there's a DOI or ISBN that can be extracted, so we don't recommend that as the default approach to adding items.

Is this a design decision or is there any plan on adding this feature ( adding books manually and then updating its metadata) in the future?

This part I'm not entirely understanding. What information do you want to enter to create the item manually? Again, you can type or paste the ISBN into Add Item by Identifier to add it that way, or you can do a web search for the book and save it from there (your library catalog, WorldCat, Google Books, Amazon, etc.).

My understanding is that the process in Zotero is the opposite of calibre to have better metadata. As recommended I should add the metadata first before adding the PDF ebook.

It's what I say above. If you have the PDF already, you can try dragging it in. If Zotero is unable to retrieve metadata for it, you can paste the ISBN into Add Item by Identifier or do a web search for the title and save the item from the sorts of sites I mention above, and then drag the PDF onto the newly created item.

Zotero will be gaining a metadata-updating feature, but this isn't really the intended use case. If you have an ISBN, there's already a feature for creating an item that way.

The feature request is their: https://forums.zotero.org/discussion/72336/feature-request-update-or-force-recheck-of-metadata

Could an option to select multiple pdfs or links and update metadata for them all instead of individually? I have a large number of linked pdfs whose metadata was not pulled but that gets pulled when I manually right click them and say update metadata.

has update-metadata been implemented?

Yes, it will.

This feature is already implemented and will be available in the Zotero beta shortly after Zotero 6. If you're running a source build you can try it now.

iseexuhs, where can one find your plugin? Also, will it work with latest Zotero 6+?
dstillman, were can we find the Zotero beta that has this feature built in?
Thank you,

@alfoil: It's not in the beta yet. We're still working on more immediate post-release issues.

Is there any progress for this feature?

Run the following code in the "Run Javascript Window" to retrieve and update metadata based on DOI. The Demo is available here (https://getquicker.net/sharedaction?code=78da8f40-e73a-46e8-da6b-08da76a0d1ac
https://www.yuque.com/chentaotao-cf9fr/gthfy4/wrc8ef)

var items = Zotero.getActiveZoteroPane().getSelectedItems();
let item = items[0]
let identifier =
{
itemType: "journalArticle",
DOI: item.getField('DOI')
};
var translate = new Zotero.Translate.Search();
translate.setIdentifier(identifier);
let translators = await translate.getTranslators();
translate.setTranslator(translators);
let newItems = await translate.translate();
let newItem = newItems[0];

function update(field){
if (newItem.getField(field)){
item.setField(field,newItem.getField(field))
}
}
item.setCreators(newItem.getCreators());

// 可根据下述网址增减需要更新的Field.
// https://www.zotero.org/support/dev/client_coding/javascript_api/search_fields

let fields=["title","publicationTitle","journalAbbreviation","volume",
"issue","date","pages","issue","ISSN","url","abstractNote"
]

for (let field of fields){
update(field);
}

newItem.deleted = true;
item.saveTx();
await newItem.saveTx();
return ("成功！");

@cttsyauchina thanks for the code! Seems to do its job

@cttsyauchina When I run your code, it says "syntax error:unexpected token; identifier." How to fix it?

@ingmar93 Thanks for your notes. It works.