Importing json from file into mongodb using mongoimport

Question

I have my json_file.json like this:

[
{
    \"project\": \"project_1\",
    \"coord1\": 2,
    \"coord2\": 10,
    \"status\": \"yes\",
    \"priority\": 7
}         


        

Answer 1

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.

Answer 2

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:

1. Array of object with valid coma positions & --jsonArray flag obligatory

   [
     {obj1},
     {obj2},
     {obj3}
   ]
   

2. 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.

Answer 3

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.