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Python Flask REST API Resourceful Blueprints Ingredient Resource

What does ForeignKeyField means and looks like in the database system?

When do we use ForeignKeyField?

models.py
import datetime

from peewee import *

DATABASE = SqliteDatabase('recipes.db')


class Recipe(Model):
    name = CharField()
    created_at = DateTimeField(default=datetime.datetime.now)

    class Meta:
        database = DATABASE


# TODO: Ingredient model
# name - string (e.g. "carrots")
# description - string (e.g. "chopped")
# quantity - decimal (e.g. ".25")
# measurement_type - string (e.g. "cups")
# recipe - foreign key

class Ingredient(Model):
    name = CharField()
    description = CharField()
    quantity = DecimalField()
    measurement_type = CharField()
    recipe = ForeignKeyField(Recipe)    # relationship to another model

    class Meta:
        database = DATABASE
resources/ingredients.py
from flask.ext.restful import Resource

import models

1 Answer

Mel Rumsey
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STAFF
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Mel Rumsey
Treehouse Staff

Hi Hanwen Zhang! A foreign key is a reference point from one table to another within a database. I suggest going through the SQL courses so that you can understand how database relationships work. Here is a video from the Querying Relational Databases course that explains Foreign Keys which also has some great visual examples. I highly recommend going through the whole course though. It helps explain databases and how they work.

Hope this helps!

Thank you