Flask Notes

Notes about Jinja2

Inheritence in jinja2: If a child html file extends a parent html file, and {% extends 'parant.html' %} is written, when the Jinja returns the contents of child.html, only the contents of parent.html, contents before where {% extends 'parant.html' %} was written and the contents surrounded by {% block blabla %} in child.html will be returned.

parent.html:

<!DOCTYPE html>
<html>
<body>
    <p>some contents</p>
    {% block ablock %}
        <p>contents will be replaced by child.</p>
    {% endblock %}
</body>
</html>

child.html:

<p>
    contents before the "extends", will be returned.
</p>
{% extends "parent.html" %}
{% block ablock %}
    <p>these contents will be returned instead of the contents in parent.html. </p>
{% endblock %}
<p>
    Any contents below "extends", and not surrounded by "block" will not be returned.
</p>

Final returned contents:

<p>
    contents before the "extends", will be returned.
</p>
<!DOCTYPE html>
<html>
<body>
    <p>some contents</p>

    <p>these contents will be returned instead of the contents in parent.html. </p>

</body>
</html>

Difference between 127.0.0.1 and 0.0.0.0

In ipv4, all addresses with prefix 127 are loop back addresses. Any requests sent to a loop back address will be looped back, as if the device receives the request rather than sending the request.

0.0.0.0 means invalid, unknown or non-applicable target. However, on general 0.0.0.0 represents all the ipv4 addresses a device has, if that device is not a router. With an application listening to 0.0.0.0, all requests sent to any addresses the target has will be processed.

Therefore, in some sense, 0.0.0.0 represents local machine actually.

posted on 2022-06-23 18:28 AI思阅读(7) 评论(0) 收藏举报