List All Expenses

Add a GET endpoint that returns all stored expenses

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The problem

Right now, your API can create expenses but has no way to retrieve them. You can add data, but you cannot see what you added. A GET endpoint solves this by returning everything stored in the dictionary.

How it works

The expenses dictionary stores each expense as a value. Calling expenses.values() returns all the values, but FastAPI needs a list to serialize the response as JSON. Wrapping it in list() converts it to a format FastAPI can return.

list(expenses.values())  # [{"id": 1, "description": "Lunch", ...}, ...]

Instructions

Add the @app.get("/expenses") decorator above the function.
Define a function named list_expenses that takes no parameters.
Return list(expenses.values()).

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from datetime import datetime
from fastapi import FastAPI
from pydantic import BaseModel, Field, field_validator
from typing import Literal, Optional

app = FastAPI()

class Expense(BaseModel):
    description: str = Field(min_length=1)
    amount: float = Field(gt=0)
    category: Literal["food", "transport", "entertainment", "utilities", "other"]
    date: Optional[str] = None

    @field_validator("date")
    @classmethod
    def validate_date_format(cls, v):
        if v is not None:
            try:
                datetime.strptime(v, "%Y-%m-%d")
            except ValueError:
                raise ValueError("Date must be in YYYY-MM-DD format")
        return v

expenses = {}
counter = 0

@app.post("/expenses", status_code=201)
def create_expense(expense: Expense):
    global counter
    counter += 1
    expenses[counter] = {"id": counter, **expense.model_dump()}
    return expenses[counter]

# Step 1: Add @app.get("/expenses")
# Step 2: Define list_expenses
# Step 3: Return list(expenses.values())

List All Expenses

The problem

How it works

Instructions

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