原文链接: http://www.kylin-ux.com/2017/04/26/database-package-sqlalchemy-sqlalchemy.ext.declarative.api.DeclarativeMeta转json

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from sqlalchemy.ext.declarative import DeclarativeMeta
from datetime import datetime
import json
class AlchemyEncoder(json.JSONEncoder):
    _visited_objs = []
    def default(self, obj):
        if isinstance(obj.__class__, DeclarativeMeta):
            # don't re-visit self
            if obj in AlchemyEncoder._visited_objs:
                return None
            AlchemyEncoder._visited_objs.append(obj)
            # an SQLAlchemy class
            fields = {}
            for field in [x for x in dir(obj) if not x.startswith('_') and x != 'metadata']:
                data = obj.__getattribute__(field)
                try:
                    if isinstance(data, datetime):
                        data=data.strftime('%Y-%m-%d %H:%M:%S')
                    json.dumps(data) # this will fail on non-encodable values, like other classes
                    fields[field] = data
                except TypeError:
                    fields[field] = None
            return fields
        return json.JSONEncoder.default(self, obj)
def new_alchemy_encoder():
    _visited_objs = []
    class AlchemyEncoder(json.JSONEncoder):
        def default(self, obj):
            if isinstance(obj.__class__, DeclarativeMeta):
                # don't re-visit self
                if obj in _visited_objs:
                    return None
                _visited_objs.append(obj)
                # an SQLAlchemy class
                fields = {}
                for field in [x for x in dir(obj) if not x.startswith('_') and x != 'metadata']:
                    data = obj.__getattribute__(field)
                    try:
                        if isinstance(data, datetime):
                            data=data.strftime('%Y-%m-%d %H:%M:%S')
                        json.dumps(data) # this will fail on non-encodable values, like other classes
                        fields[field] = data
                    except TypeError:
                        fields[field] = None
                return fields
            return json.JSONEncoder.default(self, obj)
    return AlchemyEncoder

使用

1
print(json.dumps(table, cls=new_alchemy_encoder(), check_circular=False))

或者

1
print(json.dumps(table, cls=AlchemyEncoder, check_circular=False))

table为query返回值(DeclarativeMeta类型)