Building a Flexible Notification System in Django: A Comprehensive Guide

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.

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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.

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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.

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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)

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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)

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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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