How to pass variable from javascript to django views

Question

I'm trying to take input from the user from a drop-down list. I've used javascript to take input of dynamic size and then stored the input in a variable using appendChild. Now I want to send this variable back to django views where I can perform some operations on it.

I've tried using getlist and get function in django but am not able to figure out how to get the variable.

<form method = "POST" name = "myForm" onsubmit = "return validateForm()">{% csrf_token %}

    <p>Entry Condtion:</p>
    <div id ="entry-parameters"></div>
    <button type="button" onclick= "add_entry_parameter()" class="btn btn-primary m-t-15 waves-effect">Add a new Entry Condition</button> 
    <button type= "button" onclick= "remove_entry_parameter()" class= "btn btn-primary m-t-15 waves-effect">Remove Entry Condtion</button>
    <br>

    <p>Exit Condtion</p>
    <div id = "exit-parameters"></div>
    <button type="button" onclick= "add_exit_parameter()" class="btn btn-primary m-t-15 waves-effect">Add a new Exit Condition</button> 
    <button type= "button" onclick= "remove_exit_parameter()" class= "btn btn-primary m-t-15 waves-effect">Remove Exit Condtion</button>
    <br>
    <br>
    <br>    
    <input type="submit" value="submit"  >

</form>


<script>
    var list = ['open' , 'close' , 'high', 'low'];
    var addField = document.getElementById('addField');
    parameters= document.getElementById('entry-parameters');
    exit_parameters= document.getElementById('exit-parameters');

    parameters.setAttribute("name" , "parameters" );
    exit_parameters.setAttribute("name" , "exit_parameters");

    function remove_entry_parameter()
    {
        parameters.removeChild(parameters.lastElementChild);
    }
    function add_entry_parameter()
    {

            var _form = document.body.appendChild(document.createElement('form')),
            _input = _form.appendChild(document.createElement('input')),
            _condition = _form.appendChild(document.createElement('input')),
            _input2 = _form.appendChild(document.createElement('input')),
            _datalist = _form.appendChild(document.createElement('datalist'));
            _cond_list = _form.appendChild(document.createElement('datalist'));


            _input.placeholder = "First Parameter";
            _input.list = 'exampleList';
            _input.setAttribute('list','exampleList')
            _input.datalist_id = 'exampleList';

            _input2.placeholder = "Second Parameter";
            _input2.list = 'exampleList';
            _input2.setAttribute('list','exampleList')
            _input2.datalist_id = 'exampleList';

            _condition.placeholder = "Condition";
            _condition.list = 'conditionList';
            _condition.setAttribute('list','conditionList')
            _condition.datalist_id = 'conditionList';

            _datalist.id = 'exampleList';
            _cond_list.id = 'conditionList';

            var list = ['open' , 'close' , 'high' , 'low' , 'vol'];
            var cond_list = ['greater than', 'less than' , 'crossed above' , 'crossed below', 'equal to'];



            for (var i = 0; i < list.length ; i++) {
                var _option = _datalist.appendChild(document.createElement('option'));
                _option.text =list[i];   
            };
            for (var i = 0; i < cond_list.length ; i++) {
                var _option = _cond_list.appendChild(document.createElement('option'));
                _option.text = cond_list[i];   
            };

            parameters.appendChild(_form);
    }
// I've written a similar code for exit_parameters
</script>


def get_data(request):
    if request.method == 'POST':
        entry_data = request.POST.get('parameters')
        exit_data = request.POST.get('exit_parameters')
        print(entry_data)
        print(exit_data)

    return render(request, 'get_data.html' , {})

when you create the input fields through JavaScript like this do they have name="some_field_name"? within the tags? They need this for Django to pick the up — HenryM
– HenryM, Commented Jun 21, 2019 at 7:20
I don't give names because every input field of that type will have the same name and they won't be unique (which would be required to seperate them, I guess) I am passing them through a form so I thought using the name of the div tag would be the way. — user1411
– user1411, Commented Jun 21, 2019 at 7:41
Then you need to emulate django fromsets and give them names — HenryM
– HenryM, Commented Jun 21, 2019 at 7:47
So if I give form name inside the function then wouldn't the same name be applied to all the forms? I guess I forgot to mention that I'm dynamically creating form elements. Sorry, I'll edit the question — user1411
– user1411, Commented Jun 21, 2019 at 7:52

shacker · Accepted Answer · 2019-06-21 07:54:38Z

1

Your function add_entry_parameter starts by creating a new form on the page. You almost certainly want ONE form on the page -- no need to create new ones.

The selection made in the dropdown should be visible in the DOM (inspector) with a unique field name (it doesn't make sense for all fields on the form to have the same name, as you stated in a response above) -- all fields must have a unique name.

Once you've verified that the value in an existing, uniquely named field is updated when the user makes a selection, it should come through in the POST.

answered Jun 21, 2019 at 7:54

shacker

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