# FAST API 實作

## Python + VScode

## Set up the environment
1. Install **Python**
2. Install **VSCode**
3. Set up virtual environment -- **venv** (Advantages: This will not influence other projects!)
* Type `py -3 -m venv <name>` in the terminal
* The project will run the python.exe under **/venv/Scripts**
* Type `venv\Scripts\activate.bat` in the terminal
* Type `pip install fastapi` in the terminal
* The packages will exist in the **lib** folder
4. Run all the code under the virtual environment
* Install Code Runner -> Run the code with `Ctrl + Alt + N`

## FastAPI
The original route I established !!

from fastapi import FastAPI

app = FastAPI()

@app.get("/") #get() is method
def get_user(): #Function_name should be Descriptive as possible
    return {"message": "Hello World"} #Normally transfer data by json format universally

Type `uvicorn main:app` in the terminal to execute the code
Type `uvicorn main:app --reload` in the terminal can reload the page automatically

Install **Postman**

@app.post("/createposts")
# Extract all the fields in th body and convert into Python dictionary, then store it to payLoad
def create_posts(payLoad: dict = Body(...)):
    print(payLoad)
    return {"new post": f"title{payLoad['title']} content: {payLoad['content']}"}

## Why we need Schema?
Since back-end doesn't want **arbitrary** data from the front-end, we need to force the client to send data in a schema that we expect.

Import **pydantic package** to define the schema `from pydantic import BaseModel`
Link: https://pydantic-docs.helpmanual.io/

class Post(BaseModel):
    title: str
    content: str

@app.post("/createposts")
def create_posts(new_post: Post):  # Validate for us!
    print(new_post.title)
    return {"data": "new post"}

Based on the above two code, the pydantic package will help us **validate** whether the schema is correct or not.
If not,