app.py

import numpy as np
import datetime as dt

import sqlalchemy
from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import Session
from sqlalchemy import create_engine, func

from flask import Flask, jsonify


#################################################
# Database Setup
#################################################
engine = create_engine("sqlite:///Resources/hawaii.sqlite")

# reflect an existing database into a new model
Base = automap_base()
# reflect the tables
Base.prepare(engine, reflect=True)

# Save reference to the table
Measurement = Base.classes.measurement
Station = Base.classes.station

#################################################
# Flask Setup
#################################################
app = Flask(__name__)


#################################################
# Flask Routes
#################################################

@app.route("/")
def welcome():
    """List all available api routes."""
    return (
        f"Available Routes:<br/>"
        f"/api/v1.0/precipitation<br/>"
        f"/api/v1.0/stations<br/>"
        f"/api/v1.0/tobs<br/>"
        f"/api/v1.0/<start><br/>"
        f"/api/v1.0/<start>/<end>"
    )


@app.route("/api/v1.0/precipitation")
def precipitation():
    # Create our session (link) from Python to the DB
    session = Session(engine)

    """Convert the query results to a dictionary using `date` as the key and `prcp` as the value."""
    # Query dates for the last year of data
    year_ago = dt.date(2017,8,23) - dt.timedelta(days=365)
    results = session.query(Measurement.date,Measurement.prcp).filter(Measurement.date>=year_ago).all()

    session.close()

    # Convert list of tuples into normal list
    precipitation = {date:prcp for date,prcp in results}

    return jsonify(precipitation)


@app.route("/api/v1.0/stations")
def stations():
    # Create our session (link) from Python to the DB
    session = Session(engine)

    """Return a JSON list of stations from the dataset."""
    # Query all stations
    results = session.query(Station.station).all()

    session.close()

    return jsonify(results)

@app.route("/api/v1.0/tobs")
def tobs():
    # Create our session (link) from Python to the DB
    session = Session(engine)

    """Query the dates and temperature observations of the most active station for the last year of data."""
    # Query all stations
    year_ago = dt.date(2017,8,23) - dt.timedelta(days=365)
    results = session.query(Measurement.tobs).filter(Measurement.date>=year_ago).filter(Measurement.station == "USC00519281").all()

    session.close()

    return jsonify(results)

@app.route("/api/v1.0/<start>")
def temp(start):
    session = Session(engine)

    """Return a JSON list of the minimum temperature, the average temperature, and the max temperature for a given start or start-end range."""
    # Query all stations
    sel = [func.min(Measurement.tobs), func.avg(Measurement.tobs), func.max(Measurement.tobs)]
    data = session.query(*sel).filter(Measurement.date > start).all()

    session.close()

    return jsonify(data)

@app.route("/api/v1.0/<start>/<end>")
def temprange(start,end):
    session = Session(engine)

    """Return a JSON list of the minimum temperature, the average temperature, and the max temperature for a given start or start-end range."""
    # Query all stations
    sel = [func.min(Measurement.tobs), func.avg(Measurement.tobs), func.max(Measurement.tobs)]
    data = session.query(*sel).filter(Measurement.date > start).filter(Measurement.date < end).all()

    session.close()

    return jsonify(data)

if __name__ == '__main__':
    app.run(debug=True)