How to Pass a Variable Between Flask Pages

Seeking advice: What is my best way to pass a variable between Flask routes?

You can store it as session data, for instance:

from flask import request, session

def get_year():
    try:
        session["year"] = request.form['year']
    except KeyError:
        pass
    return session.get("year") # if "year" hasn't been set yet, return None

How do i pass a variable to all flask routes once?

You can do so by creating a custom render template function using the following implementation

from flask import render_template as real_render_template
from yourapp import user  # Import the user variable or set it

def render_template(*args, **kwargs):
    return real_render_template(*args, **kwargs, user=user)

it can also be done via functools.partial:

from flask import render_template as real_render_template
from yourapp import user  # Import the user variable or set it
from functools import partial

render_template = partial(real_render_template, user=user)

Flask : how to pass variables between html pages app route

Use the session to store data between requests from the same client.

from flask import session

def getvlan():
    session['vlanid'] = request.form['vlanid']
    return redirect(url_for('showvlan'))

def showvlan():
    vlanid = session['vlanid']
    ...

Use a database (or other external, persistent store) to store data in a more generally accessible sense.

How to pass variables between HTML pages using Flask

So i didn't got your approach.Below is what i did,I changed the code a bit. Hope this solves your problem.

main.py

from flask import Flask
from flask import render_template, url_for, request, redirect
app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/form', methods = ['GET', 'POST'])
def form():
    if request.method == 'POST':
        glon = request.form['glon']
        return render_template('display.html', glon=glon)

# @app.route('/return_form/<glon>', methods = ['GET', 'POST'])
# def return_form(glon):
#     return render_template('return_form.html', glon=glon)

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

index.html

<html>
<body>
    <form action ="{{ url_for('form') }}" method="post">
            Galactic Longitude: <input type="text" name="glon">
        <button type="submit">Submit</button>
    </form>
</body>
</html>

display.html

<!doctype html>
<body>

<p> {{ glon }} </p>

</body>
</html>

How can I pass a variable to a python flask app?

global myvariable=8

@app.route("/myrout", methods=["GET"])
def myfunction():
    global myvariable
    local_variable=myvariable

How to pass variable onto another route in FLASK

The problem is the way your code is organized. Variables in a function are scoped within the function, so books isn't available from the second route. In addition to that, you have a naming collision where books=books is referring to the function itself (which is defined at the module scope).

If you want to share code between routes, put it in a separate function:

def get_books(query, show_nav_bar=False):
    query = query.lower()
    query_like = '%' + query + '%'
    books = db.execute('SELECT * FROM books WHERE (LOWER(isbn) LIKE :query) OR (LOWER(title) LIKE :query) '
                    'OR (LOWER(author) LIKE :query)', {'query': query_like}).fetchall()

    if not books:
        return render_template('error.html', message='No Books were Found!', navbar=True)

    return render_template('books.html', query=query, books=books, navbar=show_nav_bar)


@app.route("/search", methods=['GET', 'POST'])
def search():
    if request.method == 'GET':
        return render_template('search.html', navbar=True)

    else:
        return get_books(request.form.get('query'), show_nav_bar=True)


@app.route("/books", methods=['GET', 'POST'])
def books():
    return get_books(request.form.get('query'))

flask pass variable from one function to another function

Where an index.html will contain:

<form action="/search.html" method="get" autocomplete="off" class="subscribe-form">
     <div class="form-group d-flex">
         <input type="text" class="form-control" placeholder="Enter your search" name="q" id="q" value="{{q}}">
         <input type="submit" value="Search" class="submit px-3">
     </div>
 </form>

Now you will see /search.html?q=top in url now you can easily pass this q=top by using q=request.args.get("q")...

@app.route("/search.html",methods=['GET'])
def search():
        q =request.args.get("q")
        d=str(q)
        var='%'+d+'%'
        myresult = Mylist.query.filter(Mylist.type.like(var)| Mylist.title.like(var)).all()