如何不將多個數據保存到 mongodb 中的集合中？

Question

如果該集合中已經存在數據，我不想保存其他數據

Answer 1

這是一個簡單的實現，如果集合中已經存在文檔，如何防止寫入文檔。

Collection.find( {}, (err, docs) => { // By not giving any arguments inside "{}", you tell MongoDB to return all the documents.
    if(docs) {  // If there are any documents already present in the Collection, this will become true and nothing will happen.
        return;
    } else {  // If there's no document already present in the Collection, new document will be added.
        Collection.save(doc);
    }
} );