Slack Tutorial Part 3 - Creating backend's business logic

In order to interact with Slack, we need to quickly build some business logic. Luckily, that is super easy with Django. We will generate some entities using Django models, and provide an admin interface so that we can create & modify them. One of the reasons I've chosen Django for this tutorial is that we can do this without building a custom UIs.

Our application will allow users to log in and report hours on their projects. They'll also be able to see other user's reports. Simple as that.

We will:

1. Create Project model that will hold information about a project
2. ProjectReport model that will be used to report hours for each project

Create reports models

1. pipenv run ./manage.py startapp projects

2. Add projects string to INSTALLED_APPS in your settings.py

3. Create Project and ProjectReport model

projects/models.py

1from django.contrib.auth import get_user_model
2from django.db import models
3
4User = get_user_model()
5
6class Project(models.Model):
7    name = models.CharField(max_length=255)
8    logo = models.ImageField(null=True, blank=True)
9
10    def __str__(self):
11        return self.name
12
13
14class ProjectReport(models.Model):
15    project = models.ForeignKey(Project, on_delete=models.CASCADE)
16    description = models.TextField()
17    hours = models.FloatField()
18    # if we delete a user we don't want to loose the reported hours
19    user = models.ForeignKey(User, on_delete=models.PROTECT)
20
21    def __str__(self):
22        return f"{self.project.name} - {self.hours} hours - {self.user.username}"

and add them to admin interface

projects/admin.py

from django.contrib import admin

from .models import Project, ProjectReport

admin.site.register(Project)
admin.site.register(ProjectReport)

4. pipenv install Pillow

We need to do this, because we've added an ImageField..

5. pipenv run ./manage.py makemigrations && pipenv run ./manage.py migrate

git push deploy master from Heroku.

🎉 You can now check our models in the admin interface.