在创建两个模型后，在两个模型之间创建关系。 （Python，Django，SQLite）

Question

Explaining based on the django tutorial for creating a library:

Say you allow a user to add a Book model to your library database. However you don't want them to add a Genre model to the Book . Instead, you have a Genre model in your database already with all listed Genre 's in the world. When the user adds a Book to your database, you want your database to add the proper Genre to your Book based on text in the Book 's summary. Say the Book has a TextField named summary and it has the words science and fiction in it when a bookinstance is created. The database will then add a Genre of science fiction to your bookinstance based on the words found in the bookinstance's summary TextField . Whether this happens at the moment of bookinstance creation or immediately after doesn't matter to me.

I am trying to do this same thing with a website that would handle logging/creating workouts. When a user adds a workout (ie book to the library) to the database, I would like the database to add a movement (ie genre for books) to the workout depending upon what text is in the workout TextField . Example below:

I add a Workout to the website with the following information as a TextField :

5 rounds of:

• 15 Pull Ups
• 30 Squats
• 200m Run

I then want the database to create the proper relationship between the workout instance and the movement models that are used in the workout instance's TextField: Pull Up, Squat, and Run.

This way I can search the database by workouts that contain pull ups, squats, or runs and this workout will show up. Each movement model also contains a 'Classification' ForeignKey of Upper Body, Lower Body etc. So searches can also be done for workouts that are Upper body only and so on.

My question is, how would I implement the model relationships between Workout, Movement, and Classification? I don't think I can use a ForeignKey or ManytoMany relationship between a workout and movement because they would both need to be added at the same time. In other words, the user would have to type the workout into the TextField and then also add which movements are in the workout. I want this to be a one step process for the user. They type in the workout, the database adds the relationship to which movements are in the workout based off what the user typed into the TextField. I assume in order for this functionality to work a relationship must be created between the workout and movement model after the workout model is created, not during. However, I'm not sure how to create this functionality on the database level.

I'm currently using SQLite as the database as it is the default with Django.

Any suggestions?

Answer 1

With this code your users will be able to choose movement and bodyPart by themselves:

from django.db import models

movement_tuple = (
    ('Pulls up', 'Pulls up'),
    ('Squats', 'Squats'),
    ('Run', 'Run')
)

body_part = (
    ('Upper Body', 'Upper Body'),
    ('Lower Body', 'Lower Body')
)

class Workout(models.Model):
    name = models.CharField(max_length=50, default=None)
    movement = models.CharField(max_length=30, choices=movement_tuple)
    body_part = models.CharField(max_length=30, choices=body_part)
    value = models.CharField(max_length=30)

    def __str__(self):
        return(self.name)

tuples are to make choice possible