photovoter_backend/main.py

from fastapi import FastAPI
import sqlite3

# use database residing here
DB_LOCATION = (
    "../testbox/photovoter.dblite"  # Q: any allowances for this being not OUR database?
)

app = FastAPI()
con = sqlite3.connect(DB_LOCATION)
con.row_factory = sqlite3.Row
cur = con.cursor()  # NB! single is enough for now, we might require multiple later


@app.get("/new_session")
async def new_session():
    """Start a new session"""
    # add session to the database
    # return new session cookie
    return {"session_id": 42}


@app.get("/next_picture/{cookie}")
async def next_picture(cookie: int):
    """Request new picture to rate."""
    # check if the cookie is valid
    cur.execute(
        """SELECT sessionid 
            FROM sessions 
            WHERE cookie = :cookie
            LIMIT 1""",
        {"cookie": cookie},
    )
    sessionid = cur.fetchone()
    if sessionid is None:
        return {
            "picture_id": -2,
            "picture_uri": "/path/to/new/session/placeholder",  # FIXME[2]
        }  # Q: do we return something specific, or just use convention here?

    # take not rated picture from the database
    # do not insert anything in the database yet
    # return this picture

    # SELECT all images EXCEPT images with marks from the current session ->
    # -> SELECT paths for these images
    # FIXME[0]: can this be done better?
    cur.execute(
        """SELECT imgid, resizedpath
                FROM images
                WHERE imgid IN  (SELECT imgid
                                    FROM images
                                    EXCEPT
                                    SELECT imgid
                                    FROM marks
                                    WHERE sessionid = :sessionid)
                LIMIT 1
    """,
        {"sessionid": sessionid["sessionid"]},
    )
    r = cur.fetchone()
    if r is not None:
        return {"picture_id": r["imgid"], "picture_uri": r["resizedpath"]}
    else:
        # All available pics have been voted for by this sessionid
        return {
            "picture_id": -1,
            "picture_uri": "/path/to/you/are/done/placeholder",  # FIXME[1]
        }  # Q: do we return something specific, or just use a convention here?


@app.get("/rate_picture/{session_id}/{picture_id}/{mark}")
async def rate_picture(session_id: int, picture_id: int, mark: int):
    """Submit a rating for the picture"""
    # check if session is valid
    # add new mark to the session table
    pass