MongoDB

• Reference: mongo shell quick reference
• list all dbs in the mongo shell: show dbs
• work with one db: use dbs
• extracting the date from ObjectId:

 const date = new Date(parseInt(doc._id.substring(0, 8), 16) * 1000); 
 // new date object when this object created.

• remove and element from a nested array:

   {
      $pull: {
        workshops: { _id: workshopId }
      }
    }

collection functions

• collection.find() alaways need .toArray() after it.