Notifications are a key component of any modern web application, ensuring users are informed and engaged. A well-implemented notification system can handle multiple channels like in-app alerts, emails, and SMS while dynamically tailoring content for a seamless user experience. In this guide, we’ll walk you through creating a robust, scalable notification system in Django.

System Features

Our notification system is designed to provide:

1. Support for Multiple Channels: Notifications via in-app alerts, email, or SMS.
2. Dynamic Content Personalization: Templates with placeholders to generate personalized messages.
3. Event-Based Triggers: Trigger notifications based on specific system or user events.
4. Status Tracking: Monitor the delivery status for email and SMS notifications.
5. Admin and System Integration: Notifications can be triggered by administrators or system events.

Defining the Models

1. Notification Templates

Templates act as the backbone of our system, storing reusable content for notifications.

from django.db import models

class ChannelType(models.TextChoices):
    APP = 'APP', 'In-App Notification'
    SMS = 'SMS', 'SMS'
    EMAIL = 'EMAIL', 'Email'


class TriggeredByType(models.TextChoices):
    SYSTEM = 'SYSTEM', 'System Notification'
    ADMIN = 'ADMIN', 'Admin Notification'


class TriggerEvent(models.TextChoices):
    ENROLLMENT = 'ENROLLMENT', 'Enrollment'
    ANNOUNCEMENT = 'ANNOUNCEMENT', 'Announcement'
    PROMOTIONAL = 'PROMOTIONAL', 'Promotional'
    RESET_PASSWORD = 'RESET_PASSWORD', 'Reset Password'

class NotificationTemplate(models.Model):
    title = models.CharField(max_length=255)
    template = models.TextField(help_text='Use placeholders like {{username}} for personalization.')
    channel = models.CharField(max_length=20, choices=ChannelType.choices, default=ChannelType.APP)
    triggered_by = models.CharField(max_length=20, choices=TriggeredByType.choices, default=TriggeredByType.SYSTEM)
    trigger_event = models.CharField(max_length=50, choices=TriggerEvent.choices, help_text='Event that triggers this template.')
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

Key Features:

• template: Text with placeholders for dynamic values like {{username}}.
• channel: Specifies whether it’s an email, SMS, or in-app notification.
• trigger_event: Associates the template with a specific event.

2. General Notifications

The Notification model links templates to users and stores any dynamic payload for personalization.

class Notification(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="notifications")
    content = models.ForeignKey(NotificationTemplate, on_delete=models.CASCADE, related_name="notifications")
    payload = models.JSONField(default=dict, help_text="Data to replace template placeholders.")
    is_read = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)

3. Channel-Specific Models

To handle emails and SMS uniquely, we define specific models.

Email Notifications

This model manages email-specific data, such as dynamic message generation and delivery tracking.

class StatusType(models.TextChoices):
    PENDING = 'PENDING', 'Pending'
    SUCCESS = 'SUCCESS', 'Success'
    FAILED = 'FAILED', 'Failed'

class EmailNotification(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='email_notifications')
    content = models.ForeignKey(NotificationTemplate, on_delete=models.CASCADE, related_name='email_notifications')
    payload = models.JSONField(default=dict)
    status = models.CharField(max_length=20, choices=StatusType.choices, default=StatusType.PENDING)
    status_reason = models.TextField(null=True)

    @property
    def email_content(self):
        """
        Populate the template with dynamic data from the payload.
        """
        content = self.content.template
        for key, value in self.payload.items():
            content = re.sub(
                rf"{{{{\s*{key}\s*}}}}",
                str(value),
                content,
            )
        return content

SMS Notifications

Similar to email notifications, SMS-specific logic is implemented here.

class SMSNotification(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='sms_notifications')
    content = models.ForeignKey(NotificationTemplate, on_delete=models.CASCADE, related_name='sms_notifications')
    payload = models.JSONField(default=dict)
    status = models.CharField(max_length=20, choices=StatusType.choices, default=StatusType.PENDING)
    status_reason = models.TextField(null=True)

    @property
    def sms_content(self):
        """
        Populate the template with dynamic data from the payload.
        """
        content = self.content.template
        for key, value in self.payload.items():
            content = re.sub(
                rf"{{{{\s*{key}\s*}}}}",
                str(value),
                content,
            )
        return content

Admin Integration

To make managing notifications easier, we register the models in the Django admin panel.

from django.contrib import admin
from notifier.models import NotificationTemplate

@admin.register(NotificationTemplate)
class NotificationTemplateAdmin(admin.ModelAdmin):
    list_display = ['title', 'channel', 'triggered_by', 'trigger_event', 'is_active']
    list_filter = ['channel', 'triggered_by', 'is_active']
    search_fields = ['title', 'trigger_event']

Notification Service

We’ll implement a service layer to manage sending notifications through various channels.

Strategy Pattern

Using the Strategy Pattern, we’ll define classes for each notification channel.

from django.db import models

class ChannelType(models.TextChoices):
    APP = 'APP', 'In-App Notification'
    SMS = 'SMS', 'SMS'
    EMAIL = 'EMAIL', 'Email'


class TriggeredByType(models.TextChoices):
    SYSTEM = 'SYSTEM', 'System Notification'
    ADMIN = 'ADMIN', 'Admin Notification'


class TriggerEvent(models.TextChoices):
    ENROLLMENT = 'ENROLLMENT', 'Enrollment'
    ANNOUNCEMENT = 'ANNOUNCEMENT', 'Announcement'
    PROMOTIONAL = 'PROMOTIONAL', 'Promotional'
    RESET_PASSWORD = 'RESET_PASSWORD', 'Reset Password'

class NotificationTemplate(models.Model):
    title = models.CharField(max_length=255)
    template = models.TextField(help_text='Use placeholders like {{username}} for personalization.')
    channel = models.CharField(max_length=20, choices=ChannelType.choices, default=ChannelType.APP)
    triggered_by = models.CharField(max_length=20, choices=TriggeredByType.choices, default=TriggeredByType.SYSTEM)
    trigger_event = models.CharField(max_length=50, choices=TriggerEvent.choices, help_text='Event that triggers this template.')
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

Notification Service

This service ties everything together, selecting the appropriate strategy based on the notification channel.

class Notification(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="notifications")
    content = models.ForeignKey(NotificationTemplate, on_delete=models.CASCADE, related_name="notifications")
    payload = models.JSONField(default=dict, help_text="Data to replace template placeholders.")
    is_read = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)

Usage Example

Here’s how you can use the notification service:

class StatusType(models.TextChoices):
    PENDING = 'PENDING', 'Pending'
    SUCCESS = 'SUCCESS', 'Success'
    FAILED = 'FAILED', 'Failed'

class EmailNotification(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='email_notifications')
    content = models.ForeignKey(NotificationTemplate, on_delete=models.CASCADE, related_name='email_notifications')
    payload = models.JSONField(default=dict)
    status = models.CharField(max_length=20, choices=StatusType.choices, default=StatusType.PENDING)
    status_reason = models.TextField(null=True)

    @property
    def email_content(self):
        """
        Populate the template with dynamic data from the payload.
        """
        content = self.content.template
        for key, value in self.payload.items():
            content = re.sub(
                rf"{{{{\s*{key}\s*}}}}",
                str(value),
                content,
            )
        return content

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