Skip to content

Latest commit

 

History

History
352 lines (260 loc) · 10.1 KB

README.md

File metadata and controls

352 lines (260 loc) · 10.1 KB
Raw

🎓🔥 CRUD operations with NodeJS and Python

🏠 Return to HOME

Hands-on PYTHON

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-python folder and curl the connection bundle like here:`
curl -L "<your bundle link here>" > /workspace/workshop-crud-with-python-and-node/crud-python/creds.zip

expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ 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-python directory. It should be about 12kb

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ ls
creds.zip         Ex02_Connect_to_Cassandra.py  Ex04_TakeOff.py  Ex06_Landing.py      Ex08_Read_Journey.py  Ex10_ReadMetrics_Paging.py
db_connection.py  Ex03_Insert_Journey.py        Ex05_Travel.py   Ex07_LstJourneys.py  Ex09_ReadMetrics.py

B - Connect your application to Cassandra

  • ✅ Install the Cassandra driver

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

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

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

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

You simply have to run the test file Ex02_Connect_to_Cassandra:

python Ex02_Connect_to_Cassandra.py

Expected output

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex02_Connect_to_Cassandra.py 
========================================
Start exercise
Your are now connected to cluster 'caas-cluster'
Success
Closing connection (up to 10s)
========================================

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:

python Ex03_Insert_Journey.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex03_Insert_Journey.py 
========================================
Start exercise
Journey created  230995ee-c697-11ea-b7a1-8c85907c08dd
Success
Closing connection (up to 10s)
========================================
  • ✅ Exercice 4, preparing statements

Exercise 4 is explicitly preparing the statement.

To run:

python Ex04_TakeOff.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex04_TakeOff.py 
========================================
Start exercise
9..8..7..6..5..4..3..2..1 Ignition
Journey 230995ee-c697-11ea-b7a1-8c85907c08dd 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.

Although it is recommended to register your types with Cluster.register_user_type(), the driver gives you some options for working with unregistered UDTS.

When you use prepared statements, the driver knows what data types to expect for each placeholder. This allows you to pass any object you want for a UDT, as long as it has attributes that match the field names for the UDT.

Read more about working with UDTs in the driver documentation:

https://docs.datastax.com/en/developer/python-driver/3.24/user_defined_types/

We are using this simple method in this exercise. See definition of the class Location here:

class Location(object):
    def __init__(self, x_coordinate, y_coordinate, z_coordinate):
        self.x_coordinate = x_coordinate
        self.y_coordinate = y_coordinate
        self.z_coordinate = z_coordinate

We then use it in one of the batch statements:

        batch = BatchStatement()
        batch.add(prepared_insertLocation, [spacecraft_name, journey_id, Location(x,y,z),readingTime,'AU' ])
        batch.add(prepared_insertSpeed, [spacecraft_name, journey_id, speed,readingTime,'km/hour' ])
        batch.add(prepared_insertTemperature, [spacecraft_name, journey_id, pressure, readingTime,'Pa' ])
        batch.add(prepared_insertPressure, [spacecraft_name, journey_id, temperature, readingTime,'K' ])

and execute the batch here:

        connection.session.execute(batch)

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

total = 1000

to run Ex05:

python Ex05_Travel.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex05_Travel.py 
0/1000 - Travelling..
1/1000 - Travelling..
2/1000 - Travelling..
3/1000 - Travelling..
4/1000 - Travelling..
5/1000 - Travelling..
.
.
.
998/1000 - Travelling..
999/1000 - Travelling..
Reading saved for journey 230995ee-c697-11ea-b7a1-8c85907c08dd
Success
  • ✅ Exercice 6: mark the journey as completed with an end time.

To run:

python Ex06_Landing.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex06_Landing.py 
========================================
Start exercise
Journey 230995ee-c697-11ea-b7a1-8c85907c08dd has now landed
Success
  • ✅ Exercice 7, Select all records from a table

To run:

python Ex07_LstJourneys.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex07_LstJourneys.py 
========================================
Start exercise
- Journey; 230995ee-c697-11ea-b7a1-8c85907c08dd  Summary: Bring Astronauts to ISS
Success
Closing connection (up to 10s)
========================================
  • ✅ Exercice 8, Select by partition

To run:

python Ex08_Read_Journey.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex08_Read_Journey.py 
========================================
Start exercise
Journey has been found
- Uid:            230995ee-c697-11ea-b7a1-8c85907c08dd
- Spacecraft:    Crew Dragon Endeavour,SpaceX
- Summary:       Bring Astronauts to ISS
- Active:        False
- Takeoff:       2020-10-06 08:21:29.211000
- Landing:       2020-10-06 08:28:29.211000
Success
Closing connection (up to 10s)
========================================
  • ✅ Exercice 9, Parsing records

To run:

python Ex09_ReadMetrics.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex09_ReadMetrics.py 
========================================
Start exercise
idx= 0 time= 2020-10-06 08:22:06.769000 value= 307.0
idx= 1 time= 2020-10-06 08:22:06.784000 value= 307.0
idx= 2 time= 2020-10-06 08:22:06.797000 value= 308.0
idx= 3 time= 2020-10-06 08:22:06.810000 value= 304.0
idx= 4 time= 2020-10-06 08:22:06.824000 value= 311.0
.
.
.
idx= 998 time= 2020-10-06 08:22:20.989000 value= 1306.0
idx= 999 time= 2020-10-06 08:22:21.002000 value= 1301.0
Success
Closing connection (up to 10s)
========================================
  • ✅ Exercice 10, Paging

To run:

python Ex10_ReadMetrics_Paging.py

Expected output:

gitpod /workspace/workshop-crud-with-python-and-node/crud-python $ python Ex10_ReadMetrics_Paging.py 
========================================
Start exercise
Page1 with  10  item(s)
idx= 0 time= 2020-10-06 08:22:06.769000 value= 307.0
idx= 1 time= 2020-10-06 08:22:06.784000 value= 307.0
idx= 2 time= 2020-10-06 08:22:06.797000 value= 308.0
idx= 3 time= 2020-10-06 08:22:06.810000 value= 304.0
idx= 4 time= 2020-10-06 08:22:06.824000 value= 311.0
idx= 5 time= 2020-10-06 08:22:06.837000 value= 305.0
idx= 6 time= 2020-10-06 08:22:06.850000 value= 313.0
idx= 7 time= 2020-10-06 08:22:06.862000 value= 309.0
idx= 8 time= 2020-10-06 08:22:06.875000 value= 310.0
idx= 9 time= 2020-10-06 08:22:06.888000 value= 309.0

Paging State= b'\x00\n\x00\x08\x00\x00\x01t\xfd\x00\xdf(\xf0\x7f\xff\xff\xf5\xf0\x7f\xff\xff\xf5\x00'

Page2 with  10  item(s)
idx= 0 time= 2020-10-06 08:22:06.900000 value= 318.0
idx= 1 time= 2020-10-06 08:22:06.913000 value= 317.0
idx= 2 time= 2020-10-06 08:22:06.926000 value= 314.0
idx= 3 time= 2020-10-06 08:22:06.938000 value= 319.0
idx= 4 time= 2020-10-06 08:22:06.951000 value= 321.0
idx= 5 time= 2020-10-06 08:22:06.964000 value= 317.0
idx= 6 time= 2020-10-06 08:22:06.977000 value= 317.0
idx= 7 time= 2020-10-06 08:22:06.991000 value= 322.0
idx= 8 time= 2020-10-06 08:22:07.003000 value= 327.0
idx= 9 time= 2020-10-06 08:22:07.017000 value= 329.0
Success
Closing connection (up to 10s)
========================================