Django可以很好地自动序列化从DB返回到JSON格式的ORM模型。
如何序列化SQLAlchemy查询结果为JSON格式?
我试过jsonpickle。编码,但它编码查询对象本身。
我尝试了json.dumps(items),但它返回
TypeError: <Product('3', 'some name', 'some desc')> is not JSON serializable
将SQLAlchemy ORM对象序列化为JSON /XML真的那么难吗?它没有任何默认序列化器吗?现在序列化ORM查询结果是非常常见的任务。
我所需要的只是返回SQLAlchemy查询结果的JSON或XML数据表示。
需要在javascript datagird中使用JSON/XML格式的SQLAlchemy对象查询结果(JQGrid http://www.trirand.com/blog/)
安装simplejson by
PIP安装simplejson并创建一个类
class Serialise(object):
def _asdict(self):
"""
Serialization logic for converting entities using flask's jsonify
:return: An ordered dictionary
:rtype: :class:`collections.OrderedDict`
"""
result = OrderedDict()
# Get the columns
for key in self.__mapper__.c.keys():
if isinstance(getattr(self, key), datetime):
result["x"] = getattr(self, key).timestamp() * 1000
result["timestamp"] = result["x"]
else:
result[key] = getattr(self, key)
return result
并将这个类继承到每个orm类,这样这个_asdict函数就会注册到每个orm类,然后。
并在任何地方使用jsonify
下面是一个解决方案,它允许您选择希望在输出中包含的关系。
注意:这是一个完整的重写,将dict/str作为一个参数,而不是一个列表。修复了一些东西..
def deep_dict(self, relations={}):
"""Output a dict of an SA object recursing as deep as you want.
Takes one argument, relations which is a dictionary of relations we'd
like to pull out. The relations dict items can be a single relation
name or deeper relation names connected by sub dicts
Example:
Say we have a Person object with a family relationship
person.deep_dict(relations={'family':None})
Say the family object has homes as a relation then we can do
person.deep_dict(relations={'family':{'homes':None}})
OR
person.deep_dict(relations={'family':'homes'})
Say homes has a relation like rooms you can do
person.deep_dict(relations={'family':{'homes':'rooms'}})
and so on...
"""
mydict = dict((c, str(a)) for c, a in
self.__dict__.items() if c != '_sa_instance_state')
if not relations:
# just return ourselves
return mydict
# otherwise we need to go deeper
if not isinstance(relations, dict) and not isinstance(relations, str):
raise Exception("relations should be a dict, it is of type {}".format(type(relations)))
# got here so check and handle if we were passed a dict
if isinstance(relations, dict):
# we were passed deeper info
for left, right in relations.items():
myrel = getattr(self, left)
if isinstance(myrel, list):
mydict[left] = [rel.deep_dict(relations=right) for rel in myrel]
else:
mydict[left] = myrel.deep_dict(relations=right)
# if we get here check and handle if we were passed a string
elif isinstance(relations, str):
# passed a single item
myrel = getattr(self, relations)
left = relations
if isinstance(myrel, list):
mydict[left] = [rel.deep_dict(relations=None)
for rel in myrel]
else:
mydict[left] = myrel.deep_dict(relations=None)
return mydict
举个关于person/family/homes/rooms的例子…把它转换成json,你只需要
json.dumps(person.deep_dict(relations={'family':{'homes':'rooms'}}))
class SqlToDict:
def __init__(self, data) -> None:
self.data = data
def to_timestamp(self, date):
if isinstance(date, datetime):
return int(datetime.timestamp(date))
else:
return date
def to_dict(self) -> List:
arr = []
for i in self.data:
keys = [*i.keys()]
values = [*i]
values = [self.to_timestamp(d) for d in values]
arr.append(dict(zip(keys, values)))
return arr
例如:
SqlToDict(data).to_dict()
安装simplejson by
PIP安装simplejson并创建一个类
class Serialise(object):
def _asdict(self):
"""
Serialization logic for converting entities using flask's jsonify
:return: An ordered dictionary
:rtype: :class:`collections.OrderedDict`
"""
result = OrderedDict()
# Get the columns
for key in self.__mapper__.c.keys():
if isinstance(getattr(self, key), datetime):
result["x"] = getattr(self, key).timestamp() * 1000
result["timestamp"] = result["x"]
else:
result[key] = getattr(self, key)
return result
并将这个类继承到每个orm类,这样这个_asdict函数就会注册到每个orm类,然后。
并在任何地方使用jsonify
虽然最初的问题可以追溯到很久以前,但这里的答案数量(以及我自己的经验)表明,这是一个不平凡的问题,有许多不同的方法,不同的复杂性和不同的权衡。
这就是为什么我构建了SQLAthanor库,它扩展了SQLAlchemy的声明性ORM,支持可配置的序列化/反序列化,您可能想看看。
该库支持:
Python 2.7, 3.4, 3.5, and 3.6.
SQLAlchemy versions 0.9 and higher
serialization/de-serialization to/from JSON, CSV, YAML, and Python dict
serialization/de-serialization of columns/attributes, relationships, hybrid properties, and association proxies
enabling and disabling of serialization for particular formats and columns/relationships/attributes (e.g. you want to support an inbound password value, but never include an outbound one)
pre-serialization and post-deserialization value processing (for validation or type coercion)
a pretty straightforward syntax that is both Pythonic and seamlessly consistent with SQLAlchemy's own approach
你可以在这里查看(我希望!)全面的文档:https://sqlathanor.readthedocs.io/en/latest
希望这能有所帮助!