python - SQLAlchemy JSON as blob/text

Question

I'm storing JSON down as blob/text in a column using MySQL. Is there a simple way to convert this into a dict using python/SQLAlchemy?

Answer 1

You can very easily create your own type with SQLAlchemy

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For SQLAlchemy versions >= 0.7, check out Yogesh's answer below

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import jsonpickle
import sqlalchemy.types as types

class JsonType(types.MutableType, types.TypeDecorator):    
    impl = types.Unicode

    def process_bind_param(self, value, engine):
        return unicode(jsonpickle.encode(value))

    def process_result_value(self, value, engine):
        if value:
            return jsonpickle.decode(value)
        else:
            # default can also be a list
            return {}

This can be used when you are defining your tables (example uses elixir):

from elixir import *
class MyTable(Entity):
    using_options(tablename='my_table')
    foo = Field(String, primary_key=True)
    content = Field(JsonType())
    active = Field(Boolean, default=True)

You can also use a different json serialiser to jsonpickle.