DjangoL Passing Data into Viet Cheat Sheet

Most pages in a project need to present data that are specific to the current user.

URL parameters

A URL often needs to accept a parameter telling it which data to access from the database. The second URL pattern shown here looks for the ID of a specific topic and stores it in the parameter topic_id.

urlpatterns = [
    url(r'^$', views.index, name='index'),
    url(r'^topics/(?P<topic_id>\d+)/$',
    views.topic, name='topic'),
]

Using data in a view

The view uses a parameter from the URL to pull the correct data from the database. In this example the view is sending a context dictionary to the template, containing data that should be displayed on the page.

def topic(request, topic_id):
    """Show a topic and all its entries."""
    topic = Topics.objects.get(id=topic_id)
    entries = topic.entry_set.order_by('-date_added')
    context = {
        'topic': topic,
        'entries': entries,
    }
    return render(request, 'learning_logs/topic.html', context)

Using data in a template

The data in the view function’s context dictionary is available within the template. This data is accessed using template variables, which are indicated by doubled curly braces. The vertical line after a template variable indicates a filter. In this case a filter called date formats date objects, and the filter linebreaks renders paragraphs properly on a web page.

{% extends 'learning_logs/base.html' %}
{% block content %}
    <p>Topic: {{ topic }}</p>
    <p>Entries:</p>
    <ul>
    {% for entry in entries %}
        <li>
            <p>{{ entry.date_added|date:'M d, Y H:i' }}</p>
            <p>{{ entry.text|linebreaks }}</p>
        </li>
        {% empty %}
        <li>There are no entries yet.</li>
        {% endfor %}
    </ul>
{% endblock content %}

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