leaft: Day 3, Sept 16th

Daily serving summation

With finishing up my last days at General Assembly, I’ve been so busy I haven’t documented my leaft entirely!

At this point, leaft is almost done. I still need to add a signup feature, but other than that, I am happy with the UI and the functionality.

When I last left off, I was still building out routes in my backend and creating relationships between my two models. I originally decided to have DailyConsumption be my parent class and WeeklyConsumption be my child class, however, it made more sense to have WeeklyConsumption be the parent, WeeklyConsumption can have a one-to-many relationship with DailyConsumption (i.e. one week can have many days).

Models for leaft

DailyConsumption has a field called weekly_consumption, which will reference the WeeklyConsumption model and summate all the servings (obtained from the daily_servings field of the DailyConsumption model) for a particular week. I specifically want to breakdown the consumption_sum method I created to summate the servings:

def consumption_sum(self):
        days = self.dailyconsumption_set.all()
        counter = 0
        for day in days:
            counter += day.daily_servings
        return counter

    weekly_total = property(fget=consumption_sum)

Let’s break it down further:

def consumption_sum(self):
        days = self.dailyconsumption_set.all()

The method def consumption_sum uses the self parameter, which is used to represent an instance (object) of the given class, meaning every time a new week is created with the WeeklyConsumption class, it is referring to the new instance of the object.

I created a variable called days which is equal to dailyconsumption_set.all(). This is all the DailyConsumption models that are related to an instance of the WeeklyConsumption class (remember, DailyConsumption is related to WeeklyConsumption by a foreign key).

The next step is the for-in loop:

counter = 0
for day in days:
   counter += day.daily_servings
return counter

The loop counts for each instance (class) of DailyConsumption (meaning, each daily consumption log) in self.dailyconsumption_set.all() related to one instance of WeeklyConsumption by the foreign key value. .all() means to take all the daily consumption logs related to a week. Then for each instance of DailyConsumption, dot notation is used to access daily_servings, which is the number of servings the user consumed in one specific day. It adds the daily servings to the counter, and I returned the counter.

To get a clearer picture of what this looks like, here is what the get request looks like in Postman for the endpoint:

https://backendproject4.herokuapp.com/meat_consumption/weekly_consumption/3/daily_consumption.

The URL uses my deployed backend URL and grabs all the daily consumptions for the 3rd weekly consumption in the database. Here is the result:

[
{
"id": 3,
"weekly_consumption_id": 3,
"owner": "narissa5",
"consumed": "No",
"daily_servings": 0,
"day_consumed": "2020-09-21T22:18:46.868Z",
"weekly_total": 2
},
{
"id": 5,
"weekly_consumption_id": 3,
"owner": "narissa5",
"consumed": "No",
"daily_servings": 0,
"day_consumed": "2020-09-22T04:00:00.000Z",
"weekly_total": 2
},
{
"id": 6,
"weekly_consumption_id": 3,
"owner": "narissa5",
"consumed": "Yes",
"daily_servings": 2,
"day_consumed": "2020-09-23T04:00:00.000Z",
"weekly_total": 2
}
]

And that’s how I used a for-in loop to summate the daily_servings! At this point, my routes are all in place and I’m ready to move onto my frontend. I will by using Vue CLI to fetch data from my backend. The next post will detail the troubles I faced there…