Simple data munging for outputting reports

report.py

import csv
from StringIO import StringIO

def rec_getattr(obj, attr, default=None):
    """Get object's attribute. May use dot notation.

    >>> class C(object): pass
    >>> a = C()
    >>> a.b = C()
    >>> a.b.c = 4
    >>> rec_getattr(a, 'b.c')
    4
    """
    if '.' not in attr:
        return getattr(obj, attr, default)
    else:
        A, L = attr.split('.', 1)
        return rec_getattr(getattr(obj, A, default), L, default)
        

class Report(object):
    data = None

    def __init__(self, objects, columns, headings=None):
        if headings and len(columns) != len(headings):
            raise ValueError("columns and headings must have the same number of entries")

        self.data = []
        self.columns = columns
        self.headings = headings and headings or columns
        self.objects = objects

        for object in self.objects:
            row = []
            for column in iter(self.columns):
                row.append(rec_getattr(object, column, None))
            self.data.append(row)

    @property
    def as_csv(self):

        csv_file = StringIO()

        writer = csv.writer(csv_file, dialect="excel", quoting=csv.QUOTE_NONNUMERIC, lineterminator="\n")
        writer.writerow(self.headings)
        for row in self.data:
            writer.writerow(row)

        return csv_file.getvalue()


    @property
    def as_json(self):
        results = []
        for row in self.data:
            results.append(dict(zip(self.headings, row)))
        return results