MongoDB is the most compatible tool in NoSQL for Node.js. Because in Node.js, it use the JSON object to exchange data among the component. And Javascript also supports many things for JSON object.

To begin with MongoDB, you have to learn some basic instructions in MongoDB, especially on command line.


Table of contents


Open command line in the path of MongoDB

When installing the MongoDB application, the default path of it can be “C:\Program Files\MongoDB\Server\4.0\bin”.

At this folder, you can open with cmd or “Open with VS code”.


Start the MongoDB

To start this application, you can use command.

mongod


Type command at the Terminal / Cmd Windows

After the above step, you will press the command “mongo” to initialize the mongo shell.

mongo

It helps you to press command directly at the cmd or Terminal of Visual Studio Code.


Show the possible database

If you want to know which databases is used in MongoDB, you will need to use the below command.

show dbs


Use the database / Create new database

With the command “use name_db”, you will make the database new if the “name_db” does not exist, or if it exists, you will use this database.

use name_db

Ex: use tech_shops

Notice: When using this command “use name_db”, you have to insert the information into this “name_db” database. If not, the application will not detect it.


Display all collections in database

show collections


Make the new collection in the database

db.createCollection('table1');

Ex: db.createCollection(‘listOfWebsite’);


Delete the database

db.dropDatabase();

Before deleting this database, you have to type the command “use name_db” to determine which database will be used.


Insert data into the collection of database

The command “db.createCollection(‘name_collection’)” will make the new collection into the database that is using. But now, you want to update data into this collection “name_collection”, you can use the below command:

db.name_collection.insert(json_string);

Ex: db.listOfWebsite.insert({ “name”: “tiki”, “link”: “https://tiki.vn”, “products”: [ “mobile”, “books” ] });

Notice: json_string is the string of json object that you have to make it.


Display all of object in collection in one line

db.name_collection.find();


Display all of object in collection in many lines

db.name_collection.find().pretty();


Update data in the specific object in collection

db.name_collection.update(
  <condition>, 
  <update>,
  {multi: true}
)

In <update>, you can use the three options:

  • $set : update the value of the field or add the field
  • $unset : delete the field that it find the collection satisfied the condition
  • $rename : modify the name of the field, not the value of the field
db.listOfWebsite.update(
  {"name": "amazon"}, 
  {$set: {"incomes": "1 billions dollar"}}, 
  {upsert: true},
  {multi: true}
);

When “multi: true” property, it means many object that satifies the condition, will be updated.

But multi property is false, it will update for one object that application finds the objects that is satified.

db.listOfWebsite.update(
  {"name": "amazon", 
  {$unset: {"incomes": "1 billions dollar"}},
  {multi: false}
)

When you see the field “unset”, it means that when it satisfies the condition, it will delete the field “incomes: "1 billion dollar"” at the first object that it found.

And “upsert” filed = update + insert. The default value of “upsert” is false. It means:

  • upsert = true : If it does not find the other fields that satifies the condition, it will automatically insert this field into the object and set value for this field.
  • upsert = false : if the object has no field, it will ignore it.

If you want to update for every documents, you can write empty in the condition like this:

db.listOfWebsite.update(
  {}, 
  {$unset: {"incomes": "1 billions dollar}},
  {multi: false}
)


Remove document in collection

db.name_collection.remove(
  <condition>, 
  {justOne: true}
)

Example:

db.listOfWebsite.remove(
  {"name": "amazon"}, 
  {justOne: true}
)


Export and Import data in MongoDB

In Export and Import, there are two options that can be used in here.

  • export / import collection
  • export / import database

Next, we will have some instructions about export / import commands.

  • export collection : mongodexport -d <name_database> -c <name_collection> -o <name_destination_json_file>

    Ex: mongoexport -d fake_tiki -c listOfWebsite -o “C:\test\listwebsite.json”

  • export database : mongodump -d <name_database> -o <name_destination_folder>

    Ex: mongodump -d fake_tiki -o “C:\test”

  • import collection : mongoimport -d <name_database> -c <name_collection> –file <name_folder>

  • import database : mongorestore -d <name_database> <name_destination_folder>

Notice: the export and import commands you have to use the system command line - cmd.exe, not mongo shell.

Thanks for your reading.