Mongoimport Failed: invalid JSON input.错误

Project needs, import local json data into mongodb, use the command under cmd

mongoimport -d datas -c title --file E:\title.json

The following error occurred

Failed: invalid JSON input.

I checked the information and researched it and found that it was a problem with the
original data format. The original data is:

{
    
     
    "_id" : ObjectId("5be19b932ab79c00013074ed"), 
    "workNumber" : "2016223045999", 
    "titles" : "李浩,发的是达到顶峰", 
    "_class" : "cn.bookcycle.scuservice.pojo.TitlePO"
}

Where the first line

“_id” : ObjectId(“5be19b932ab79c00013074ed”),

It is in the format of json v1.0
and the mongodb version I use is 4.2. The official website says that starting from 4.2, Json v2.0
should be in the following format by default

{
    
    
	"_id":{
    
    "$oid":"5be19b932ab79c00013074ed"},
	"workNumber":"2016223045999",
	"titles":"李浩,发的是达到顶峰",
	"_class":"cn.bookcycle.scuservice.pojo.TitlePO"
}

Therefore, the import fails

Solution:
Use --legacy to identify json v1.0

mongoimport -d datas -c title --file E:\title.json --legacy