flask-marshmallow

pip install flask-marshmallow

from flask import Flask
from flask_marshmallow import Marshmallow # new

app = Flask(__name__)

ma = Marshmallow(app)


class PostSchema(ma.Schema):

    class Meta:
        fiels = ('id', 'title', 'content')

post_schema = PostSchema()
posts_schema = PostSchema(many=True)