javascript - Get data from html and <do some operation on it> and pass the data back to the front end using ajax or js

Question

I am trying to get data from webpage to my flask app and after a few operations on it,the output list im trying to send it back to front end as a dropdown list.

What i have done till now:

there is a user form where the user enters details and clicks on submit and he gets a json output.

in this form,I have a search button which when the user inputs a string,that string is sent to the flask app route and few search operations are done and outputs a list of items(TILL this part it is working!)

What i need to get to work is the output list should again be sent back to the form page which i have trouble getting it to work.

This is what i have done so far:

    var successFunction = function(response) {
     /* do something here */
            $('#info').html(JSON.stringify(data, null, '   '));
    });
}
$(function(){
        $('#btnSignUp').click(function(){

                $.ajax({
                        url: '/signUp',
                        data: $('form').serialize(),
                        type: 'POST',
                        success: successfunction(response)
                        error: function(error){
                                console.log(error);
                        }
                });
        });
});

the flask app has something like this:

from flask import Flask, render_template, request,jsonify,url_for
import json,os,re
app = Flask(__name__)

@app.route('/',methods=['GET','POST'])
def form():
        if request.method == 'POST': #this block is only entered when the form is submitted
                result = { key: value[0] if len(value) == 1 else value
                      for key, value in request.form.iterlists()
                        }
                return json.dumps(result,indent=2)
        return render_template('form_backup1.html')


@app.route("/signUp", methods=["POST","GET"])
def signUp():
        jsdata = request.form['Nitro']
        <couple of find and search operations the output of which is in 
        this dropdown_list list>
        return jsonify(dropdown_list)

if __name__ == '__main__':
   app.run(host="0.0.0.0",port="5000",debug = True)

snipped html page just to show the search box:

      <div id='nitroo'>
      Nitro_search: <input type="text" placeholder="Apply Nitro" name="Nitro" id="Nitro">
      <button id="btnSignUp" class="btn btn-lg btn-primary btn-block" type="button">Search</button>
       <pre id="info"></pre>

As I said I am able to get the text entered by the user in the html form when he clicks on search. the output lists from python is where I am having trouble of getting to front end.

Any help on this would be much appreciated.

Thanks

Answer 1

You can use ajax with Jquery. You can see this doc for more details.

How to proceed:

1. Configure js scripts

In your HTML file template:

• Load Jquery:

Load Jquery preferably before any other javascript files.

Either statically:

<script type=text/javascript src="{{url_for('static', filename='jquery.js') }}"> </script>

Or using Google’s AJAX Libraries API:

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="{{url_for('static', filename='jquery.js') }}">x3C/script>')</script>

• Add a dynamic path to the site:

  <script type=text/javascript>$SCRIPT_ROOT = {{ request.script_root|tojson|safe }}; </script>
  

  This script tag sets a global variable to the prefix to the root of the application.

  2. On the side of Flask

Write a function that will take as argument the value entered in the form by the user, perform search operations and return a JSON object with the list you want to display.

@app.route("/_signUp")
def signUp():
    myString = request.args.get('myString')

    """couple of find and search operations the output of which is in 
    this dropdown_list list"""

    dropdown_list = ['A', 'B', 'C'] #sample

    return jsonify(dropdown_list=dropdown_list)

3. Back in the HTML code

Write a script that will retrieve the data entered, send them in Ajax to the server and display the information returned by the server.

<script type=text/javascript>
    $(function(){
        $('#btnSignUp').bind('click', function(){
            $.getJSON($SCRIPT_ROOT + '/_signUp', {
                myString: $('input[name="Nitro"]').val(),
            },function(data){
                $('#info').append('<li>' + data.dropdown_list[0] + '</li>' );//A
                $('#info').append('<li>' + data.dropdown_list[1] + '</li>' );//B
                $('#info').append('<li>' + data.dropdown_list[2] + '</li>' );//C
            }
        });
    });
</script>
<div id='nitroo'>
    Nitro_search: <input type="text" placeholder="Apply Nitro" name="Nitro" id="Nitro">
    <button id="btnSignUp" class="btn btn-lg btn-primary btn-block" type="button">Search</button>
   <pre id="info"></pre>
</div>

See this link for more details.