search nested lists of python objects (great for mongoengine)

get_embedded

def get_embedded(self, hierarchy, key, value, indexes=False):
    """get a list containing the ordered indexes of embedded documents.
    A recursive depth first search replacing the nested for loops normally required
    to iterate through nested objects contained within lists to find a single object 
    that has a specific value for a specific key.  
    
    
    Keyword Arguments:
    hierarchy -- a list of keys needed to access the list containingthe next level of objects to search
    key -- the string name of the member to match value too 
    value -- the value that key is being matched too
    indent -- used to make the print easy to read       
    indexes -- if True, return a list of indexes ordered the same as the hierarchy, 
                    useful for targeting/updating embedded mongo documents 
    """
    index = 0
    domain = hierarchy.pop(0)
    if len(hierarchy) == 0:
        #if we're at the lowest level of the hierarchy, compare the key and value
        for embedded in self[domain]:            
            if embedded[key] == value:
                if indexes==True:
                    return [index]
                else:
                    return embedded
            index += 1
    else:
        for embedded in self[domain]: 
            #if the key and value matched at a lower level, add this level's index to the address list
            output = embedded.get_embedded(hierarchy, key, value, indexes=indexes)
            if output != None: 
                if indexes==True:
                    output.insert(0, index)
                    return output
                else:
                    return output
            index += 1
    hierarchy.insert(0, domain)
    return None

This is best used if included in a base class. I use it in the base class for my mongoengine documents, completely removing the need to write nested for loops to search for deeply embedded documents. This makes the db query vs in memory trade-off less painful.