Creating the producer class to send the notifications
Published: 2023-06-27 15:51:04

Title: Exploring the RabbitMQProducer Class for Message Publishing

Table of Contents:
1. Overview
2. Code Explanation
3. Conclusion

## 1. Overview
In this blog post, we will explore the `RabbitMQProducer` class, which is responsible for publishing messages to a RabbitMQ exchange. We will examine the code and discuss its functionality and error handling.

## 2. Code Explanation
The code snippet defines the `RabbitMQProducer` class, which handles publishing messages to a RabbitMQ exchange. Let's explore its functionality and error handling in more detail.

### 2.1. Constructor (`__init__`)
The constructor initializes the `RabbitMQProducer` instance by accepting a `connection` parameter, which represents an instance of the `RabbitMQConnection` class. It sets the `connection` property of the instance to the provided `connection` object and initializes the `channel` property to `None`.

### 2.2. `publish_message` method
The `publish_message` method is responsible for publishing a message to the RabbitMQ exchange. It takes three parameters: `exchange`, `routing_key`, and `data`.

```python
import json
from pika import BasicProperties, exceptions as pika_exceptions

class RabbitMQProducer:
    def __init__(self, connection):
        self.connection = connection
        self.channel = None

    def publish_message(self, exchange, routing_key, data):
        if self.channel is None:
            self.channel = self.connection.get_channel()

        if self.channel is not None:
            try:
                self.channel.exchange_declare(exchange=exchange, exchange_type="topic")
                message = json.dumps(data)
                properties = BasicProperties(content_type="application/json", delivery_mode=2)
                self.channel.basic_publish(
                    exchange=exchange,
                    routing_key=routing_key,
                    body=message,
                    properties=properties,
                )
                print(f"Message sent to exchange: {exchange} with routing_key {routing_key}")
            except pika_exceptions.ConnectionClosedByBroker:
                print("Connection closed by broker. Failed to publish the message")
        else:
            print("Failed to obtain a channel for publishing the message")
```

- If the `channel` property of the instance is `None`, it calls the `get_channel` method of the `connection` object to obtain a channel.

- If the `channel` is not `None`, it performs the following steps:
  - Declares the exchange using the `exchange_declare` method of the `channel` object, specifying the `exchange` and `exchange_type`.
  - Converts the `data` parameter to JSON format using `json.dumps`.
  - Creates a `BasicProperties` object with content type set to "application/json" and delivery mode set to 2 (persistent message).
  - Publishes the message to the exchange using the `basic_publish` method of the `channel` object, specifying the `exchange`, `routing_key`, `body`, and `properties`.
  - Prints a success message indicating the exchange and routing key of the message.

- If a `ConnectionClosedByBroker` exception is raised during the publish process, it catches the exception and prints a failure message indicating the connection was closed by the broker.

- If the `channel` is `None`, it prints a failure message indicating that it failed to obtain a channel for publishing the message.

## 3. Conclusion
The `RabbitMQProducer` class provides a convenient way to publish messages to a RabbitMQ exchange. It encapsulates the logic for establishing a channel, declaring an exchange, and publishing a message with the specified routing key and data. The class handles potential exceptions, such as a closed connection or failure to obtain a channel

, and provides informative error messages.

By using this class, you can easily integrate message publishing capabilities into your applications that communicate with RabbitMQ.