html模板为

index模板：

{% extends "base.html" %}
{% import "bootstrap/wtf.html" as wtf %}
{% block title %}博客{% endblock %}

{% block page_content %}
<div class="page-header">
    <h1>您好, {% if current_user.is_authenticated %}{{ current_user.username }}{% else %}游客{% endif %}!</h1>
</div>
<div>
{% if current_user.can(Permission.WRITE_ARITICLES) %}
    {{ wtf.quick_form(form) }}
    {% endif %}
</div>
{% include '_posts.html' %}
{% endblock %}

_post.html模板为：

<ul class="posts">
{% for post in posts %}
    <li class="post">
        <div class="post-thumbnails">
            <a href="{{ url_for('.user', username=post.author.username) }}">
                <img class="img-rounded profile-thumbnails" src="{{  url_for('static', filename='avatar/') }}{{ post.author.gravatar() }}">
            </a>
        </div>
        <div class="post-content">
            <div class="post-date">{{ moment(post.timestamp).fromNow() }}</div>
            <div class="post-author"><a href="{{ url_for('.user', username=post.author.username) }}">{{ post.author.username }}</a></div>
            <div class="post-body">{{ post.body }}</div>
        </div>
    </li>
{% endfor %}
</ul>

视图函数为：

@main.route('/', methods=['GET','POST'])
def index():
    form = PostForm()
    if current_user.can(Permission.WRITE_ARTICLES) and \
            form.validate_on_submit():
        post = Post(body = form.body.data, author=current_user._get_current_object())
        db.session.add(post)
        return redirect(url_for('.index'))
    posts = Post.query.order_by(Post.timestamp.desc()).all()
    return render_template('index.html',form=form, posts=posts)


@main.route('/user/<username>')
def user(username):
    print(username)
    user = User.query.filter_by(username=username).first_or_404()
    posts = user.posts.order_by(Post.timestamp.desc()).all()
    return render_template('user.html', user=user,posts =posts)

这是怎么回事，哪位大神帮忙看看，万分感谢