Django – Updating value only for the last item of list

This is how my ToDoapp looks like

The date change works only for the last item in the list but for other items it throws the error:

ValidationError at /
['“” value has an invalid date format. It must be in YYYY-MM-DD format.']

I see that irrespective of "Update" button I press, it passes only the last item’s id and date.

Find my code below:

Index.html

{% extends 'base.html' %}
{% block content %}

<h3 style = "margin-bottom: 20px"><strong>To Do List App</strong></h3>

<form method="POST">
    {%csrf_token%}
<ul class="list-group">

{% for task in tasklist %}
<li class="list-group-item d-flex justify-content-between align-items-center">
    <input type='hidden' name = 'task_id' value='{{task.id}}'>{{task.tasks}}
    <span class="badge bg-primary rounded-pill">{{task.duedate}}
        <input type="date" name="datepick" />
        <input type='submit' value ='Update'>   
    </span>
</li>
{% endfor %}

</form>

Views.py

def index(request):
    if request.method == "POST":
        task_id = request.POST.get('task_id')
        task=Task.objects.get(id=task_id)
        datepick = request.POST.get('datepick')
        task.duedate = datepick
        task.save()
    tasklist = Task.objects.all()
    return render(request, 'index.html', {'tasklist':tasklist})

Models.py

class Task(models.Model):
    tasks = models.CharField(max_length=200)
    duedate = models.DateField(blank=True)

I feel that mistake is in the HTML file and I’m not familiar with HTML.