Simple implementation of Python+MongoDB auto-increment key value

Background

Recently I was writing a testing toolbox, which has a bug recording system. Because I used Django and MongoDB to implement the background, I encountered a The question is, how to implement an auto-incrementing field.

It is very easy to implement a traditional relational database. You just need to directly set an auto-increment field. When inserting data, you don’t need to worry about this key value. Just worry about the data you process. The auto-increment will be automatically implemented. function, but non-relational databases don’t seem to have this function (or I don’t know). Baidu later discovered that they were all MongoDB setting methods, which were not what I wanted.

Solution ideas

Baidu has not found a good idea, so it can only solve it by itself. My idea is very simple, and the fields will not Self-increasing, then create a self-increasing plan yourself.

I found that the method modified in MongoDB has a $inc method, which can realize the auto-increment of int type. Then it's very simple. Create a collection yourself, and then there is only one int field in this collection. Every time you insert data, just come to this collection to get the ID, and then call the $inc method, then automatic increment will be realized. plan.

Code display

Python is still very simple to implement. Python and Django are very compatible. The code is as follows:

def bugPlus(self):
  """
  bugID自增
  :return:True
  """
  db = self.__chooseCollection(config.COLLECTION['bugID'])
  db.update_one({"bugID": self.getBugID()}, {"$inc": {"bugID": 1}})
  return True

After each insertion is successful, calling this method can realize the automatic increment of the ID.

def getBugID(self):
  """
  获取当前bug的最新编号
  :return:None
  """
  db = self.__chooseCollection(config.COLLECTION['bugID'])
  rst = db.find_one()
  return rst['bugID']

Before inserting, call this method, so that the ID inserted every time data is inserted is the ID that is auto-incremented.

Disadvantages

Of course, this method still has shortcomings. More methods are used when calling, so the method needs to be confirmed. Whether the execution is successful, otherwise the ID inserted next time will not be the data after the auto-increment. Each time the method is called more than once, performance will decrease.

Others

If there is a better way to implement it, please tell me!

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