app.py

from flask import Flask, render_template, abort, request, jsonify
import nltk
from nltk.sentiment.vader import SentimentIntensityAnalyzer

app = Flask(__name__)

output = {}

def sentiment(sentence):

    nltk.download('vader_lexicon')
    sid = SentimentIntensityAnalyzer()
    score = sid.polarity_scores(sentence)['compound']
    if(score>0):
        return "Positive"
    else:
        return "Negative"

@app.route("/", methods = ["GET","POST"])
def sentimentRequest():
    if request.method == "POST":
        sentence = request.form['q']
        sent = sentiment(sentence)
        output['sentiment'] = sent
        return jsonify(output)
    else:
        sentence = request.args.get('q')
        sent = sentiment(sentence)
        print(sentence)
        output['sentiment'] = sent
        return jsonify(output)

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