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🎓🔥 CRUD operations with NodeJS and Python

🏠 Return to HOME

Hands-on NODEJS

A - Download the bundle to securely connect to your Astra instance

  • ✅ Display the summary screen and locate the connect button.

pic

  • ✅ On the connect screen pick drivers

pic

  • ✅ Right-click on Download Secure Connect Bundle and save the link location to the clipboard`

Driver page pic

Get the link Screenshot 2020-10-05 at 10 09 49

  • ✅ Now in gitpod, navigate to the crud-nodejs folder and curl the connection bundle like here:`
curl -L "<your bundle link here>" > /workspace/workshop-crud-with-python-and-node/crud-nodejs/creds.zip

expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ curl -L "<your bundle link here>" > creds.zip
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 12354  100 12354    0     0  28797      0 --:--:-- --:--:-- --:--:-- 28797

You should end up with a file creds.zip in the crud-nodejs directory. It should be about 12kb

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ ls
creds.zip         Ex02_Connect_to_Cassandra.js  Ex04_TakeOff.js  Ex06_Landing.js      Ex08_Read_Journey.js  Ex10_ReadMetrics_Paging.js  package.json       README.md
db_connection.js  Ex03_Insert_Journey.js        Ex05_Travel.js   Ex07_ListJourney.js  Ex09_ReadMetrics.js   node_modules                package-lock.json

B - Connect your application to Cassandra

  • ✅ Install the Cassandra driver

The npm package manager is already install in gitpod, as such you simply have to :

npm install cassandra-driver
  • ✅ Set up the Connection with Astra

Ex01: Modify the db_connection.js file with your credentials:

// This is the Zip file you downloaded
const SECURE_CONNECT_BUNDLE = '/workspace/workshop-crud-with-python-and-node/crud-nodejs/creds.zip'
// This is the username, recommended value was SUser
const USERNAME = "SUser";
// This is the password, recommended value was SPassword1
const PASSWORD = "SPassword1";
// This is the keyspace name, recommended value was spacecraft
const KEYSPACE = "spacecraft";
  • ✅ Test the Connection to Astra

You simply have to run the test class Ex02_Connect_to_Cassandra:

node Ex02_Connect_to_Cassandra.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex02_Connect_to_Cassandra.js 
========================================
Start exercise
========================================
Your are now connected to cluster 'caas-cluster'
SUCCESS

C - Insert using Simple Statements and Prepared Statements

  • ✅ Exercice 3

In this exercise we are creating a new journey.

Pay attention to the line where we are creating the journey id. For the purpose of the exercise, we are using a hard-coded time uuid for the journey ID. You can create your own, new one, but remember to update the details in the other exercise files.

Exercise 3 is using a SimpleStatement for the insert.

To run:

node Ex03_Insert_Journey.js

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex03_Insert_Journey.js 
========================================
Start exercise
========================================
Journey created : 84121060-c66e-11ea-a82e-f931183227ac
SUCCESS
  • ✅ Exercice 4, preparing statements

To run:

node Ex04_TakeOff.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex04_TakeOff.js 
========================================
Start exercise
9..8..7..6..5..4..3..2..1 Ignition
========================================
Journey 84121060-c66e-11ea-a82e-f931183227ac has now taken off
SUCCESS
  • ✅ Exercice 5: Inserts using UDTs and Batches

The table spacecraft_location_over_time is using a user-defined type, location.

With the Node.js driver, you can retrieve and store UDTs using JavaScript objects.

See definition of object here:

var location = {
   x_coordinate: x,
   y_coordinate: y,
   z_coordinate: z
}

We then use it in one of the batch statements:

var myBatch = [
 { query: insertSpeed, params: [spacecraft_name, journey_id, speed,readingTime,'km/hour' ] },
 { query: insertTemperature, params: [spacecraft_name, journey_id, pressure, readingTime,'Pa' ] },
 { query: insertPressure, params: [spacecraft_name, journey_id, temperature, readingTime,'K' ] },
 { query: insertLocation, params: [spacecraft_name, journey_id, location,readingTime,'AU' ] }
]

and execute the batch here:

const result = await connection.client.batch(myBatch, { prepare: true })

Pay attention to the number of metrics we collect, and modify to your preference.

var total = 1000

to run Ex05:

node Ex05_Travel.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex05_Travel.js 
========================================
Start exercise
{1/1000} - Travelling..
{2/1000} - Travelling..
{3/1000} - Travelling..
{4/1000} - Travelling..
{5/1000} - Travelling..
.
.
.
{999/1000} - Travelling..
{1000/1000} - Travelling..
Reading saved for journey 84121060-c66e-11ea-a82e-f931183227ac
========================================
  • ✅ Exercice 6: mark the journey as completed with an end time.

To run:

node Ex06_Landing.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex06_Landing.js 
========================================
Start exercise
========================================
Journey 84121060-c66e-11ea-a82e-f931183227ac has now landed
SUCCESS
  • ✅ Exercice 7, Select all records from a table

To run:

node Ex07_ListJourney.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex07_ListJourney.js 
========================================
Start exercise
========================================
- Journey: 84121060-c66e-11ea-a82e-f931183227ac Summary: Bring Astronauts to ISS
SUCCESS
  • ✅ Exercice 8, Select by partition

To run:

node Ex08_Read_Journey.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex08_Read_Journey.js 
========================================
Start exercise
========================================
Journey has been found
- Uid:           84121060-c66e-11ea-a82e-f931183227ac
- Spacecraft:    Crew Dragon Endeavour,SpaceX
- Summary:       Bring Astronauts to ISS
- Active:        false
- Takeoff:       2020-10-06T07:43:31.419Z
- Landing:       2020-10-06T07:46:56.515Z
SUCCESS
  • ✅ Exercice 9, Parsing records

To run:

node Ex09_ReadMetrics.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex09_ReadMetrics.js 
========================================
Start exercise
========================================
idx:0, time=2020-10-06T07:45:32.915Z, value=302.1598637573277
idx:1, time=2020-10-06T07:45:33.263Z, value=307.5410825416916
idx:2, time=2020-10-06T07:45:33.278Z, value=307.0571217360859
idx:3, time=2020-10-06T07:45:33.293Z, value=304.7200155558933
idx:4, time=2020-10-06T07:45:33.307Z, value=312.923770628411
idx:5, time=2020-10-06T07:45:33.321Z, value=312.07888261288326
.
.
.
idx:998, time=2020-10-06T07:45:46.994Z, value=1299.4336218766407
idx:999, time=2020-10-06T07:45:47.007Z, value=1300.4481347583946
SUCCESS
  • ✅ Exercice 10, Paging

To run:

node Ex10_ReadMetrics_Paging.js

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-nodejs $ node Ex10_ReadMetrics_Paging.js 
========================================
Start exercise
========================================
Page1: 5 items
idx:1, time=2020-10-06T07:45:32.915Z, value=302.1598637573277
idx:2, time=2020-10-06T07:45:33.263Z, value=307.5410825416916
idx:3, time=2020-10-06T07:45:33.278Z, value=307.0571217360859
idx:4, time=2020-10-06T07:45:33.293Z, value=304.7200155558933
idx:5, time=2020-10-06T07:45:33.307Z, value=312.923770628411


Page2: 5 items
idx:5, time=2020-10-06T07:45:33.321Z, value=312.07888261288326
idx:5, time=2020-10-06T07:45:33.335Z, value=314.71636649213457
idx:5, time=2020-10-06T07:45:33.350Z, value=312.9582991476898
idx:5, time=2020-10-06T07:45:33.365Z, value=317.5249145018446
idx:5, time=2020-10-06T07:45:33.379Z, value=313.2526364182921