$addToSet

https://www.mongodb.com/docs/manual/reference/operator/update/addToSet/

  1. [
  2.   {
  3.     "name": "s1",
  4.     "skills": ["python", "shell"]
  5.   },
  6.   {
  7.     "name": "s2",
  8.     "skills": ["perl", "r"]
  9.   }
  10. ]
  1. # 更新单个元素到列表，自动去重
  2. _update = {
  3.     '$addToSet': [
  4.         'skills': 'perl'
  5.     ]
  6. }
  7. col.update({'name': 's1'}, _update)  # skills: ['python', 'shell', 'perl']
  9. # 更新列表素到列表，自动去重
  10. _update = {
  11.     '$addToSet': [
  12.         'skills': {'$each': ['perl', 'r']}
  13.     ]
  14. }
  15. col.update({'name': 's1'}, _update)  # skills: ['python', 'shell', 'perl', 'r']