title: How to read in user input on a webpage in Flask
body: <p>I'm trying to create a basic web app that has an HTML form on the root landing page, and then after submission, run a postgresql query with the desired input and redirect the user to a page with a generated matplotlib chart of their input. In my main function, I have the following:</p>
  
  <pre><code>@app.route('/', methods=['POST'])
  def main():
      return render_template("main.html")
  </code></pre>
  
  <p>So let's say I have my main html file being rendered by the flask app. I have another route below:</p>
  
  <pre><code>@app.route('/query', methods=['POST'])
  def queryPage():
      # code to execute query with information 
      # passed from the main.html template
      # then generate chart via matplotlib via returned information
      return render_template("query.html")
  </code></pre>
  
  <p>I'm confused as to how to get my input from the form in main.html to send information back to the application for rendering at the /query endpoint. If someone could elaborate on this, I'd appreciate it. Front end is not my strong suit. Thanks!</p>