我收到此错误：“UnboundLocalError：分配前引用的局部变量‘Requesting_books’”

Question

i want to use the variable " Requesting_books ", but everytime i am getting this error : "UnboundLocalError: local variable 'Requesting_books' referenced before assignment". Actually i want to use this variable in my jinja template so that i can show search results. Please Help me !

@app.route('/request books', methods=['GET', 'POST'])
@app.route('/get books', methods=['GET', 'POST'])
def requesting_for_books():
    if request.method == 'POST':
        requesting = mongo.db.mylogin
        Requesting_books = requesting.find_one({'name' : request.form['bookname']})
    return render_template('get_books.html', title="Get Books", my_book=Requesting_books['name'])

Answer 1

You should add an else block because if request.method is not 'POST' no variable will be assigned .

@app.route('/request books', methods=['GET', 'POST'])
@app.route('/get books', methods=['GET', 'POST'])
def requesting_for_books():
    if request.method == 'POST':
        requesting = mongo.db.mylogin
        Requesting_books = requesting.find_one({'name' : request.form['bookname']})
        return render_template('get_books.html', title="Get Books", my_book=Requesting_books['name']) #<--- Move return into the if block
    else:
        #Do something if request.method is not "POST"