Sunday, May 31, 2020

Re: Ajax and Django and jQuery - .attr()

This isn't a jQuery issue, it's a JavaScript/ECMAScript issue. When you use the "arrow function" style like "() => { ...code... }" then certain variables are not bound into the function contact, including "this". https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

To get "this" inside your event handler you need to use "function () { code... }".

$(".upvote").click( function () {
            let answerid = $(this).attr("answer-id");
            console.log(answerid);
            $.post("{% url 'upvote' %}", {answer_id:answerid});
});

But also, it's bad bad form to define your own attribute names on HTML. Use the "data-answer-id" attribute name to do this, and in your code access it with $(this).data("answer-id").

On Sun, May 31, 2020 at 2:19 PM Jan Gregorczyk <jnk.gregorczyk@gmail.com> wrote:
I have a problem with Ajax and Django templates. I'm new to Ajax and jquery.
Console log at the end of the script prints undefined. I don't know why let answerid = $(this).attr("answer-id"); doesn't extract attribute from this line: <i class="upvote" answer-id="{{answer.id}}">&#8593</i>
I also want to know if using template tags in javascript scripts like here $.post("{% url 'upvote' %}", {answer_id:answerid}) is a good idea.


{% extends 'base.html' %}
{% block title %}{{question.title|truncatechars:52}}{% endblock %}
{% block content %}
<h1>{{question.title}}</h1>
<p>{{question.content}}</p>
{% for answer in question.answers.all %}
<h3>{{answer.author}}</h3>
<p>{{answer.content}}</p>
<p>
<i class="upvote" answer-id="{{answer.id}}">&#8593</i>
{{answer.votes.count}}
<i class="downvote" answer-id="{{answer.id}}">&#8595</i>
</p>
{% endfor %}
<form method="POST" action="{% url 'answer' question.id %}">
{% csrf_token %}
{{form.as_p}}
<input type="submit" value="Odpowiedz">
</form>
{% endblock %}
{% block javascript %}
{% load static %}
<script>
//upvote and downvote script
var csrftoken = window.Cookies.get('csrftoken');
function csrfSafeMethod(method) {
// these HTTP methods do not require CSRF protection
return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));
}
$.ajaxSetup({
beforeSend: function(xhr, settings) {
if (!csrfSafeMethod(settings.type) && !this.crossDomain) {
xhr.setRequestHeader("X-CSRFToken", csrftoken);
}
}
});
$(".upvote").click( () => {
let answerid = $(this).attr("answer-id");
console.log(answerid);
$.post("{% url 'upvote' %}", {answer_id:answerid});
});
</script>
{% endblock %}

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