How does mongodb query a single field?

  mongodb, question

I used find to get all the data in the whole table. I only want to operate one field (i.e. add, delete, modify and check one field).
Json data is as follows

{
 "date": "20171123",
 "stories": [
 {
 "images": "1.jpg",
 "title": "Title 1"
 },
 {
 "images": "2.jpg",
 "title": "Title 2"
 },
 {
 "images": "3.jpg",
 "title": "Title 3"
 }
 ],
 "top_stories": [
 {
 "top_images": "top1.jpg",
 "top_title": "top1"
 },
 {
 "top_images": "top2.jpg",
 "top_title": "top2"
 },
 {
 "top_images": "top3.jpg",
 "top_title": "top3"
 }
 ]
 }

I just want to get the data in the field stories. how should I write it?

> db.a.find({},{stories:1,_id:0})
 {"stories": [{"images": "1.jpg", "title": "title 1" }, {"images": "2.jpg",
 "title": "title 2" }, {"images": "3.jpg", "title": "title 3"}]}
 
 > db.a.update ({}, {$ push: {stories: {"images": "4.jpg", "title": "title 4"}}}})

图片描述

图片描述