Dot notation question

[badlydrawnrob]

@Youngestdev Hi there, I'm working my way through your book and enjoying it so far, but I have a simple question about the syntax (it's been a long time since I've used Python) ... by default item = {"id": 1} dictionary can only be accessed using item["id"] syntax, yet the examples in the book use dot notation (item.id).

1. Are we accessing raw json here?
2. Or is there something special that FastApi is doing in the background:
   • like enabling dot notation for dictionaries

I'm assuming our data in chapter 02 is using the todo_list (a list of ToDo dictionaries) and converting requests from json to dict (which we're accessing).

I can't seem to find this information anywhere.

[badlydrawnrob]

It seems that the following PUT:

for todo in todo_list:
        if todo["id"] == id:
            todo[".item"] = todo_data # relace with the request body

            return { "message": "To-do updated successfully" }

Fails with the ["id"] key accessor (returns Internal Server Error), so it must be raw json we're working with here? Now I'm a little confused!

[Youngestdev]

Hi, @badlydrawnrob!

I'm glad you're enjoying the book so far.

For the todos, we're making use of Pydantic Basemodel to represent the schema hence the use of dot notation to access the fields.

class Todo(BaseModel):
    id: int
    item: str

For the PUT method you have, the error is as a result of the wrong way you're accessing the Todo data which is a Basemodel object instance and not a dictionary. You can reference the code in the folder here for clarification.

Let me know if this answers your question.

[badlydrawnrob]

@Youngestdev Thanks for the speedy reply.

I think I understand now, so basically the json is being converted to a ToDo or whatever class you set up, and you create an object:

from pydantic import BaseModel

class ToDo(BaseModel):
    id: int
    item: str

# json
one = { "id": 1, "item": "Finish the chapter" }
# our model
todo = ToDo(**one)

And then you're accessing the attributes with dot notation:

>>> todo
ToDo(id=1, item='Finish the chapter')
>>> todo.item
'Finish the chapter'

I'm so used to using typed functional (Haskell) I've totally forgot how object-oriented languages work 🤦‍♂

[Youngestdev]

Yes, exactly!