Java MongoDB to insert the JSON file documents into a collection

Objective and Prerequisites

Objective: This segment introduces implementation of how to insert the JSON (JavaScript Object Notation) file documents into a collection in MongoDB using Java.

Prerequisites: MongoDB setup is installed and running in the background. Also, the project has been developed and executed in Eclipse IDE (Integrated Development Environment).

To run the following program, you need to download the MongoDB Java driver jar file Download MongoDB Java driver. Once downloaded, you can import the library by right-clicking on your project in Eclipse -> Properties -> Java Build Path -> Libraries -> Add External JARs...

Start MongoDB (running mongo.exe)

MongoDB shell version v4.2.3
connecting to: mongodb://127.0.0.1:27017/
MongoDB server version: 4.2.3

> show dbs
DB      0.000GB
admin   0.000GB
config  0.000GB
local   0.000GB

> use DB
switched to db DB

> db.getCollectionNames()
[ "holders" ]

> db.holders.find().pretty()
>

In the following program, database and collection automatically get created. If database and collection already exist in MongoDB, then new documents will get inserted into an existing collection. Furthermore, we will be inserting documents into a holders collection using the JSON file, and once all the documents inserted, we will retrieve those using find() method.

kw.json

{ "account_no" : 2562348989, "name" : "James Moore", "city" : "Phoenix", "DOB" : ISODate("1985-05-26T00:00:00Z"), "bank" : "Barclays", "amount" : 5000, "loan" : [ { "Personal" : 5660, "Home" : 15000 } ] }
{ "account_no" : 2562348990, "name" : "Donald Taylor", "city" : "Irvine", "DOB" : ISODate("1990-08-20T00:00:00Z"), "bank" : "Citi", "amount" : 7000, "loan" : [ { "Home" : 10000, "Car" : 20000 } ] }
{ "account_no" : 2562348991, "name" : "Edward Parkar", "city" : "Irvine", "DOB" : ISODate("1994-01-29T00:00:00Z"), "bank" : "ICICI", "amount" : 95000, "loan" : [ { "Personal" : 25000, "Home" : 450000, "Car" : 10000 } ] }
{ "account_no" : 2562348992, "name" : "Ryan Bakshi", "city" : "Mumbai", "DOB" : ISODate("1982-01-14T00:00:00Z"), "bank" : "Citi", "amount" : 50000, "loan" : [ { "Personal" : null, "Home" : null, "Car" : null } ] }

KW.java

import java.io.BufferedReader;
import java.io.FileReader;

import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;

class KW
{
    @SuppressWarnings("resource")
    public static void main(String[] args)
    {
        try
        {
            MongoClient mc = new MongoClient("localhost", 27017);
            MongoDatabase md = mc.getDatabase("DB");
            MongoCollection<Document> collection = md.getCollection("holders");
            
            BufferedReader br = new BufferedReader(new FileReader("kw.json"));
            String docs=null;
            while((docs=br.readLine())!=null)
            {
                collection.insertOne(Document.parse(docs));
            }
            System.out.println("Documents inserted successfully");
            
            FindIterable<Document> fi=collection.find();
            MongoCursor<Document> cursor=fi.iterator();
            while(cursor.hasNext()) 
            {
                System.out.println(cursor.next());
            }
            mc.close();
        }
        catch(Exception e)
        {
            System.out.println(e.getMessage());
        }
    }
}

Output

Documents inserted successfully
Document{{_id=5e7ca9bff19e77642089963b, account_no=2562348989, name=James Moore, city=Phoenix, DOB=Sun May 26 05:30:00 IST 1985, bank=Barclays, amount=5000, loan=[Document{{Personal=5660, Home=15000}}]}}
Document{{_id=5e7ca9c0f19e77642089963c, account_no=2562348990, name=Donald Taylor, city=Irvine, DOB=Mon Aug 20 05:30:00 IST 1990, bank=Citi, amount=7000, loan=[Document{{Home=10000, Car=20000}}]}}
Document{{_id=5e7ca9c0f19e77642089963d, account_no=2562348991, name=Edward Parkar, city=Irvine, DOB=Sat Jan 29 05:30:00 IST 1994, bank=ICICI, amount=95000, loan=[Document{{Personal=25000, Home=450000, Car=10000}}]}}
Document{{_id=5e7ca9c0f19e77642089963e, account_no=2562348992, name=Ryan Bakshi, city=Mumbai, DOB=Thu Jan 14 05:30:00 IST 1982, bank=Citi, amount=50000, loan=[Document{{Personal=null, Home=null, Car=null}}]}}

MongoDB Instance

> db.holders.find().pretty()
{
    "_id" : ObjectId("5e7ca9bff19e77642089963b"),
    "account_no" : NumberLong("2562348989"),
    "name" : "James Moore",
    "city" : "Phoenix",
    "DOB" : ISODate("1985-05-26T00:00:00Z"),
    "bank" : "Barclays",
    "amount" : 5000,
    "loan" : [
        {
            "Personal" : 5660,
            "Home" : 15000
        }
    ]
}
{
    "_id" : ObjectId("5e7ca9c0f19e77642089963c"),
    "account_no" : NumberLong("2562348990"),
    "name" : "Donald Taylor",
    "city" : "Irvine",
    "DOB" : ISODate("1990-08-20T00:00:00Z"),
    "bank" : "Citi",
    "amount" : 7000,
    "loan" : [
        {
            "Home" : 10000,
            "Car" : 20000
        }
    ]
}
{
    "_id" : ObjectId("5e7ca9c0f19e77642089963d"),
    "account_no" : NumberLong("2562348991"),
    "name" : "Edward Parkar",
    "city" : "Irvine",
    "DOB" : ISODate("1994-01-29T00:00:00Z"),
    "bank" : "ICICI",
    "amount" : 95000,
    "loan" : [
        {
            "Personal" : 25000,
            "Home" : 450000,
            "Car" : 10000
        }
    ]
}
{
    "_id" : ObjectId("5e7ca9c0f19e77642089963e"),
    "account_no" : NumberLong("2562348992"),
    "name" : "Ryan Bakshi",
    "city" : "Mumbai",
    "DOB" : ISODate("1982-01-14T00:00:00Z"),
    "bank" : "Citi",
    "amount" : 50000,
    "loan" : [
        {
            "Personal" : null,
            "Home" : null,
            "Car" : null
        }
    ]
}

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