在 Flask 中对 SQLAlchemy 结果集进行 jsonify [英] jsonify a SQLAlchemy result set in Flask

问题描述

我正在尝试对 Flask/Python 中的 SQLAlchemy 结果集进行 jsonify.

I'm trying to jsonify a SQLAlchemy result set in Flask/Python.

Flask 邮件列表建议使用以下方法 http://librelist.com/browser//flask/2011/2/16/jsonify-sqlalchemy-pagination-collection-result/#04a0754b63387f87e59dda564bde426e:

The Flask mailing list suggested the following method http://librelist.com/browser//flask/2011/2/16/jsonify-sqlalchemy-pagination-collection-result/#04a0754b63387f87e59dda564bde426e :

return jsonify(json_list = qryresult)

但是我收到以下错误:

TypeError: <flaskext.sqlalchemy.BaseQuery object at 0x102c2df90> 
is not JSON serializable

我在这里俯瞰什么?

我发现了这个问题:如何将 SqlAlchemy 结果序列化为 JSON? 看起来很相似，但我不知道 Flask 是否有一些魔法可以使它更容易，就像邮件列表帖子所建议的那样.

I have found this question: How to serialize SqlAlchemy result to JSON? which seems very similar however I didn't know whether Flask had some magic to make it easier as the mailing list post suggested.

为了澄清，这就是我的模型的样子

for clarification, this is what my model looks like

class Rating(db.Model):

    __tablename__ = 'rating'

    id = db.Column(db.Integer, primary_key=True)
    fullurl = db.Column(db.String())
    url = db.Column(db.String())
    comments = db.Column(db.Text)
    overall = db.Column(db.Integer)
    shipping = db.Column(db.Integer)
    cost = db.Column(db.Integer)
    honesty = db.Column(db.Integer)
    communication = db.Column(db.Integer)
    name = db.Column(db.String())
    ipaddr = db.Column(db.String())
    date = db.Column(db.String())

    def __init__(self, fullurl, url, comments, overall, shipping, cost, honesty, communication, name, ipaddr, date):
        self.fullurl = fullurl
        self.url = url
        self.comments = comments
        self.overall = overall
        self.shipping = shipping
        self.cost = cost
        self.honesty = honesty
        self.communication = communication
        self.name = name
        self.ipaddr = ipaddr
        self.date = date

推荐答案

看来您实际上还没有执行您的查询.尝试以下操作:

It seems that you actually haven't executed your query. Try following:

return jsonify(json_list = qryresult.all())

:jsonify 的问题是，通常对象不能自动 jsonify.甚至 Python 的日期时间也失败了 ;)

: Problem with jsonify is, that usually the objects cannot be jsonified automatically. Even Python's datetime fails ;)

我过去所做的是向需要序列化的类添加一个额外的属性(如 serialize).

What I have done in the past, is adding an extra property (like serialize) to classes that need to be serialized.

def dump_datetime(value):
    """Deserialize datetime object into string form for JSON processing."""
    if value is None:
        return None
    return [value.strftime("%Y-%m-%d"), value.strftime("%H:%M:%S")]

class Foo(db.Model):
    # ... SQLAlchemy defs here..
    def __init__(self, ...):
       # self.foo = ...
       pass

    @property
    def serialize(self):
       """Return object data in easily serializable format"""
       return {
           'id'         : self.id,
           'modified_at': dump_datetime(self.modified_at),
           # This is an example how to deal with Many2Many relations
           'many2many'  : self.serialize_many2many
       }
    @property
    def serialize_many2many(self):
       """
       Return object's relations in easily serializable format.
       NB! Calls many2many's serialize property.
       """
       return [ item.serialize for item in self.many2many]

现在我可以做的视图:

return jsonify(json_list=[i.serialize for i in qryresult.all()])

希望这有帮助;)

:如果您有更复杂的对象或循环引用，请使用像 marshmallow 之类的库.

: In case you have more complex objects or circular references, use a library like marshmallow).

这篇关于在 Flask 中对 SQLAlchemy 结果集进行 jsonify的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！