JSON > DICT > OBJ

posted

Weird little situation came up while I was working on a research project last night. I've been taking a string representation of a dictionary and converting it into JSON to render with handlebars.js but It's finally gotten to the point that I needed a bit more from my templates.

I have jinja already in the project but problem was, jinja works really well on objects and lists/sets/tuples of objects, not so much on lists of dictionaries.

So here's what I did:
To quickly reconvert any string representation of a data structure use literal_eval from ast:

>>> import ast
>>> context = "{'a':1, 'b':2, 'foo':'bar'}"
>>> d = ast.literal_eval(context)
>>> print type(d)
<type 'dict'>


The working class

# the following class definition will take a dictionary as an argument on init
# and create an object with all keys as attributes and their corresponding values
class DictToObject:
  def __init__(self, dictionary):
    for k, v in dictionary.items():
      setattr(self, k, v)


Then to use it do this:

>>> context = "{'a':1, 'b':2, 'foo':'bar'}"
>>> d = ast.literal_eval(context)
>>> p = DictToObject(d)
>>> print(p.a)
1
>>> print(p.foo)
'bar'


The way this used to work was a python dictionary of database results was converted to a string and placed into Redis. I retrieved the string and converted it to a dictionary again only to then json.dump it back to the original AJAX call and have it passed to a handlebar template. I know, messy.

Now, after I get the string back into a dictionary, I convert it's key values into to an object, zip it up in a list and return a rendered template with the data. Presto.

Python, Jinja2, Tricks

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