I have my json_file.json like this:
[
{
"project": "project_1",
"coord1": 2,
"coord2": 10,
"status": "yes",
"priority": 7
},
{
"project": "project_2",
"coord1": 2,
"coord2": 10,
"status": "yes",
"priority": 7
},
{
"project": "project_3",
"coord1": 2,
"coord2": 10,
"status": "yes",
"priority": 7
}
]
When I run the following command to import this into mongodb:
mongoimport --db my_db --collection my_collection --file json_file.json
I get the following error:
Failed: error unmarshaling bytes on document #0: JSON decoder out of sync - data changing underfoot?
If I add the --jsonArray flag to the command I import like this:
imported 3 documents
instead of one document with the json format as shown in the original file.
How can I import json into mongodb with the original format in the file shown above?
Perhaps the following reference from the MongoDB project blog could help you gain insight on how arrays work in Mongo:
https://blog.mlab.com/2013/04/thinking-about-arrays-in-mongodb/
I would frame your import otherwise, and either:
a) import the three different objects separately into the collection as you say, using the --jsonArray flag; or
b) encapsulate the complete array within a single object, for example in this way:
{
"mydata":
[
{
"project": "project_1",
...
"priority": 7
}
]
}
HTH.
The mongoimport
tool has an option:
--jsonArray
treat input source as a JSON array
Or it is possible to import from file
containing same data format as
the result of db.collection.find()
command.
Here is example from
university.mongodb.com courseware
some content from grades.json
:
{ "_id" : { "$oid" : "50906d7fa3c412bb040eb577" }, "student_id" : 0, "type" : "exam", "score" : 54.6535436362647 }
{ "_id" : { "$oid" : "50906d7fa3c412bb040eb578" }, "student_id" : 0, "type" : "quiz", "score" : 31.95004496742112 }
{ "_id" : { "$oid" : "50906d7fa3c412bb040eb579" }, "student_id" : 0, "type" : "homework", "score" : 14.8504576811645 }
As you can see,
no array used and
no comma delimiters between documents either.
I discover, recently,
that this complies with the JSON Lines text
format .
Like one used in apache.spark.sql.DataFrameReader.json()
method .
I faced opposite problem today, my conclusion would be:
If you wish to insert array of JSON objects at once, where each array entry shall be treated as separate dtabase entry, you have two options of syntax:
Array of object with valid coma positions & --jsonArray flag obligatory
[
{obj1},
{obj2},
{obj3}
]
Use file with basically incorrect JSON formatting (i.e. missing ,
between JSON object instances & without --jsonArray flag
{obj1}
{obj2}
{obj3}
If you wish to insert only an array (i.e. array as top-level citizen of your database) I think it's not possible and not valid, because mongoDB by definition supports documents as top-level objects which are mapped to JSON objects afterwards. In other words, you must wrap your array into JSON object as ALAN WARD pointed out.