python-How to save HTML code and add it to html file?

I'm building a web page to show articles. In my database, I have to attributes, one of which is used to put Markdown code and the other to save HTML code converted from the Markdown code. I want to get the HTML and add it to my base HTML. I use Flask framework and SQLAlchemy and the data is saved in sqlite database. My model:

class Post(db.Model):
id = db.Column(db.Integer, primary_key=True)
title = db.Column(db.String)
body = db.Column(db.String)
timestamp = db.Column(db.String)
tag = db.Column(db.String)
info = db.Column(db.String)
body_markdown = db.Column(db.String)

and my view function:

def post(post_id):
post = db.session.query(Post).filter(Post.id == post_id).first()
return render_template('post.html',
                       post = post,)

Firstly, I tried:

<div class="post-body">
            {{post.body}}
</div>

It shows the whole string with HTML tag. post.body.decode("utf-8") and post.body.decode("ascii") didn't work, either. When I debug the program, I found that the database returns u'string'. How can I get pure HTML code and apply it in my base HTML file?