Question

I have a python dictionary like this

{'OR': [{'AND': [{'column': 'XXX', 'operator': '=', 'value': u'M'}, {'column': 'XXX', 'operator': '=', 'value': 'N'}]}, {'column': 'YYY', 'operator': '>=', 'value': '3.0'}]}

Now, i want to convert it to something like

{'$or': [{'$and': [{'XXX': 'M'}, {'YYY': 'N'}]}, {'YYY': {u'$gte': 3.0}}]}

Which is clearly the equivalent pymongo statement I believe.

the code I have written so far is like this :

FILTMAP = {'>=': '$gte', '<=': '$lte', '>': '$gt', '<': '$lt', "!=":"$ne"}
CONJUNCTION_MAP = {"AND":"$and", "OR":"$or"}

def gen_mongo_filters_json(filter, supplied_key="")
    first_key = filters.keys()[0]
    if first_key == 'OR' or first_key == 'AND':

        if supplied_key == "":      

            return_dict[CONJUNCTION_MAP[first_key]] = []
        else:            
            temp_dict[CONJUNCTION_MAP[first_key]] = []
            #return_dict[supplied_key] = temp_dict
        for i in range (len(filters[first_key])):
            if supplied_key == "":               
                return_dict[CONJUNCTION_MAP[first_key]].append(gen_mongo_filters_json(filters[first_key][i], first_key))
            else:
                temp_dict[CONJUNCTION_MAP[first_key]].append(gen_mongo_filters_json(filters[first_key][i], first_key))
                return_dict[CONJUNCTION_MAP[supplied_key]].append(temp_dict)
    else:
        operator = filters['operator']
        if operator == "=":
            ret_dict = {filters['column']:filters['value']
            return ret_dict
        else:
            operator = FILTMAP[operator]
            ret_dict = {filters['column']:{operator:filters['value']}}
            return ret_dict
    return return_dict

The output it generates is :

 {u'$or': [{u'$and': [{u'Engine': u'MSN'}, {u'Engine': u'Google'}]}, {u'$and': [{u'Engine': u'MSN'}, {u'Engine': u'Google'}]}, {...}, {u'Imps': {u'$gte': 3.0}}]}

Which is near to the solution but not the exact one. It works fine for dictionaries like

{'AND': [{'column': 'XXX', 'operator': '=', 'value': 'M'}, {'column': 'XXX', 'operator': '=', 'value': 'N'}]}

OR

{'column': 'YYY', 'operator': '>', 'value': '1000'}

can you point to me a direction?

(the idea is to create a generic one. so, i would like to generate equivalent to any valid python dictionary into pymongo statement. the minimum is the last one)

Answer 1

Your example code does not run, but given that a dict

{'OR': [{'AND': [{'column': 'XXX', 'operator': '=', 'value': 'M'}, {'column': 'YYY', 'operator': '=', 'value': 'N'}]}, {'column': 'YYY', 'operator': '>=', 'value': '3.0'}]}

should be convertet to

{'$or': [{'$and': [{'XXX': 'M'}, {'YYY': 'N'}]}, {'YYY': {'$gte': 3.0}}]}

use something like this:

FILTMAP = {'>=': '$gte', '<=': '$lte', '>': '$gt', '<': '$lt', "!=":"$ne"}
CONJUNCTION_MAP = {"AND":"$and", "OR":"$or"}

def convert_column(dic):
    if not dic['operator'] in FILTMAP:
        return {dic['column']: dic['value']}
    else:
        value = float(dic['value']) if dic['operator'] == "!=" else dic['value']
        return {dic['column']: {FILTMAP[dic['operator']]: value}}

def convert(dic):
    for k,v in dic.items():
        if isinstance(v, list):
            if k in CONJUNCTION_MAP:
                k = CONJUNCTION_MAP[k]
            return {k: [convert(i) for i in v]}
        else:
            return convert_column(dic)

I don’t know if it’s important to convert '3.0' to 3.0. The line

value = float(dic['value']) if dic['operator'] == "!=" else dic['value']

is quite hackish, you want replace it with some appropriate logic to handle those cases.