在Flask中声明一个SQLAlchemy结果集 [英] jsonify a SQLAlchemy result set in Flask
问题描述
return jsonify（json_list = qryresult ）
然而，我收到以下错误：
TypeError：< flaskext.sqlalchemy.BaseQuery object at 0x102c2df90>
不是JSON序列化
我在这里忽略了什么？
我发现这个问题：如何将SqlAlchemy结果序列化为JSON？，这看起来非常相似，但是我不知道Flask是否有一些神奇的功能让邮件列表的帖子变得更容易。
编辑：澄清，这就是我的模型看起来像$ / b>
class Rating（db.Model）：
$ b $ __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（） ）
$ b $ 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 =全部
self.shipping =运输
self.cost =成本
self.honesty =诚实
self.communication = communication
self.name = name
self.ipaddr = ipaddr
self.date = date
看来你实际上还没有执行过你的查询。请试试以下内容：
return jsonify（json_list = qryresult.all（））
：jsonify的问题是，通常这些对象不能自动进行json化。甚至Python的日期时间也失败了;）
我通常做的是添加一个额外的属性（比如 serialize ）到需要序列化的类：
$ p $ def $ date $ time $ $ $ $ $ $反序列化datetime对象到字符串如果值为None：
return
return [value.strftime（％Y-％m-％d），value.strftime（ ％H：％M：％S）]
class Foo（db.Model）：
＃... SQLAlchemy defs here ..
def __init __（self，。 ..）：
＃self.foo = ...
通过
@property
def serialize（self）：
Return object数据以易于序列化的格式
返回{
'id'：self.id，$ b $'modified_at'：dump_datetime（self.modified_at），
＃这是一个例子如何处理Many2Many关系
'many2many'：self.serialize_many2many
}
@pr operty
def serialize_many2many（self）：
以易于序列化的格式返回对象的关系。
NB！调用many2many的序列化属性。
return [item.serialize for self.many2many中的项目]
<现在的视图，我可以做：
$ $ p $ return jsonify（json_list = [i.serialize for i in qryresult.all （）]）
希望这有助于;）
I'm trying to jsonify a SQLAlchemy result set in Flask/Python.
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)
However I'm getting the following error back:
TypeError: <flaskext.sqlalchemy.BaseQuery object at 0x102c2df90>
is not JSON serializable
What am I overlooking here?
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.
Edit: 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
It seems that you actually haven't executed your query. Try following:
return jsonify(json_list = qryresult.all())
[Edit]: Problem with jsonify is, that usually the objects cannot be jsonified automatically. Even Python's datetime fails ;)
What I have usually done, is to add 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 serializeable 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 serializeable format.
NB! Calls many2many's serialize property.
"""
return [ item.serialize for item in self.many2many]
And now for views I can just do:
return jsonify(json_list=[i.serialize for i in qryresult.all()])
Hope this helps ;)
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