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MongoDB — Creating Documents — 1


Everything about creating documents in MongoDB

mongod --dbpath <path>

to change path to database

mongod -- logpath <path>

to change path to log file
mongodb config file

  • Create config file named mongod.cfg
  • Add the following to it

storage:
  dbPath: <path>
systemLog:
  destoination: file
  path: <file path>
  • mongod -f <path to config file>

mongod

For running MongoDB server

mongo

For running MongoDB shell

CRUD Operations

Create

insertOne()

db.collection.insertOne({field: "value"});

insertMany()

db.collection.insertOne([{field: "value"}, {field: "value"}]);

Ordered Insert in MongoDB

db.hobbies.insertMany([{_id: "yoga", name: "Yoga"}, {_id: "cooking", name: "Cooking"}, {_id: "hiking", name: "Hiking"}], {ordered: true})
{ordered: true} is the default behaviour of insert statements

Unordered Insert in MongoDB

If you want mongodb to continue trying to insert other documents even after one or more failing due to any reason, you must set ordered to false. See example below:
db.hobbies.insertMany([{_id: "yoga", name: "Yoga"}, {_id: "cooking", name: "Cooking"}, {_id: "hiking", name: "Hiking"}], {ordered: false})

WriteConcern

Setting Acknowledge to false

Setting acknowledge to false increases speed but the down side is that you don't get acknowledgement as well as _id if data is inserted successfully. What one can do is fetch data to check.

Example: Run the following statements in mongo shell

db.hobbies.insertOne({name: "Dancing"}, {writeConcern: {w: 0}})
db.hobbies.find().pretty()

Setting Acknowledge to false

This can be explicitly be done but is also the default behavior.

Example: Run the following statements in mongo shell

db.hobbies.insertOne({name: "Trekking"}, {writeConcern: {w: 1}})
db.hobbies.find().pretty()

Adding to Journal before Inserting to DB

Setting Journal to true

Setting journal to true slows down operation as data is first added to journal and from there it is added to db.
db.hobbies.insertOne({name: "Disco Dancing"}, {writeConcern: {w: 1, j: true}})
db.hobbies.find().pretty()

Setting Journal to false

This is the default behavior. So one need not explicitly mention but one can. Setting journal to false directly adds to db.
db.hobbies.insertOne({name: "Listening Music"}, {writeConcern: {w: 1, j: false}})
db.hobbies.find().pretty()

Set Timeout for Create Operation

Setting wtimeout milliseconds

Setting journal to true slows down operation as data is first added to journal and from there it is added to db. The following example sets timeout to 200 milliseconds.
db.hobbies.insertOne({name: "Playing Video Games"}, {writeConcern: {w: 1, j: true, wtimeout: 200}})
db.hobbies.find().pretty()

Not setting wtimeout

This is the default behavior. So one need not explicitly mention. The below example will wait for response even if it takes very long for acknowledgement.
db.hobbies.insertOne({name: "Playing Drums"}, {writeConcern: {w: 1, j: true}})
db.hobbies.find().pretty()
That is all about creating documents in MongoDB

Importing Data from JSON File

One can import data from json files using the following command in terminal.


mongoimport data.json -d <database name> -c <collection name> --jsonArray --drop

mongoimport is used to import data from a json file. after mongoimport we mention the file name followd by -d and database name, fllowed by -c and collection name. --jsonArray is mentioned when there are more than one records in json file. --drop is mentioned when we want to instruct to replace entire collection with content from the file. If --drop is not mentioned, records are simply appended.

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