export to csv, import from csv

"""adapted from django-csvimport
Usage:
python manage.py model_objects_to_csv --database=...
or
python manage.py model_objectsto_csv --import --database=...

Note for export:
The exported CSV files will be in:
(database_name)/(app_name)/(class_name.csv)


Note for import:
Import delete all model data in the app. It can be turned off by setting CLEANUP_BEFORE_IMPORT=False
Use IMPORT_ONLY_THIS_MODEL="MyClassName" to import only it.

"""
from django.core.exceptions import ObjectDoesNotExist
from django.core.management.base import CommandError, NoArgsCommand
from django.conf import settings
from optparse import make_option
from django.db import DEFAULT_DB_ALIAS, models
from django.utils.importlib import import_module
import inspect, sys, csv, os, re
from datetime import datetime


ALLOW_IMPORT = False
CLEANUP_BEFORE_IMPORT = True
IMPORT_ONLY_THIS_MODEL = ""#"CLASSNAME"
MODULES_TO_EXPORT = ["mysite.myapp.models",
                    ]

MODULES_TO_IMPORT = MODULES_TO_EXPORT

INTEGER = ['BigIntegerField', 'IntegerField', 'AutoField',
           'PositiveIntegerField', 'PositiveSmallIntegerField']
FLOAT = ['DecimalField', 'FloatField']
NUMERIC = INTEGER + FLOAT
BOOLEAN = ['BooleanField', 'NullBooleanField']
BOOLEAN_TRUE = [1, '1', 'Y', 'Yes', 'yes', 'True', 'true', 'T', 't']


def my_get_model(app_label, model_name):
    Model = getattr(import_module(app_label), model_name, None)
    return Model


def is_django_model(model):
    if hasattr(model, '__bases__') and model.__bases__ and model.__bases__[0].__name__ == 'Model':
        return True
    return False


def find_dups(seq):
    seen = set()
    seen_add = seen.add
    # adds all elements it doesn't know yet to seen and all other to seen_twice
    seen_twice = set(x for x in seq if x in seen or seen_add(x))
    # turn the set into a list (as requested)
    return list(seen_twice)


def check_fkey(key, field):
    """ Build fkey mapping via introspection of models """
    #TODO fix to find related field name rather than assume second field
    if not key.endswith('_id'):
        if field.__class__ == models.ForeignKey:
            key += '(%s|%s)' % (field.related.parent_model.__name__,
                                field.related.parent_model._meta.fields[1].name,)
    return key


def insert_fkey(foreignkey, rowcol, app_label):
    """ Add fkey if not present
        If there is corresponding data in the model already,
        we do not need to add more, since we are dealing with
        foreign keys, therefore foreign data
    """
    fk_key, fk_field = foreignkey
    if fk_key and fk_field:
        fk_model = my_get_model(app_label, fk_key)
        matches = fk_model.objects.filter(**{fk_field + '__exact':
                                                 rowcol})

        """if not matches:
            key = fk_model()
            key.__setattr__(fk_field, rowcol)
            key.save()
        """

        rowcol = fk_model.objects.filter(**{fk_field + '__exact': rowcol})[0]
    return rowcol


def make_mappings(mappings):
    """
    Parse the mappings, and return a list of them.
    """
    if not mappings:
        return []

    def parse_mapping(args):
        """
        Parse the custom mapping syntax (column1=field1(ForeignKey|field),
        etc.)

        >>> parse_mapping('a=b(c|d)')
        [('a', 'b', '(c|d)')]
        """

        pattern = re.compile(r'(\w+)=(\w+)(\(\w+\|\w+\))?')
        mappings = pattern.findall(args)

        mappings = list(mappings)
        for mapping in mappings:
            mapp = mappings.index(mapping)
            mappings[mapp] = list(mappings[mapp])
            mappings[mapp][2] = parse_foreignkey(mapping[2])
            mappings[mapp] = tuple(mappings[mapp])
        mappings = list(mappings)

        return mappings

    def parse_foreignkey(key):
        """
        Parse the foreignkey syntax (Key|field)

        >>> parse_foreignkey('(a|b)')
        ('a', 'b')
        """

        pattern = re.compile(r'(\w+)\|(\w+)', re.U)
        if key.startswith('(') and key.endswith(')'):
            key = key[1:-1]

        found = pattern.search(key)

        if found != None:
            return (found.group(1), found.group(2))
        else:
            return None

    mappings = mappings.replace(',', ' ')
    mappings = mappings.replace('column', '')
    return parse_mapping(mappings)


class Command(NoArgsCommand):
    help = """"Export model data into csv"""
    option_list = NoArgsCommand.option_list + (
        make_option('--database', action='store', dest='database',
            default=DEFAULT_DB_ALIAS, help='Nominates a database to run this command against '
                                           'Defaults to the "default" database.'),
        make_option('--dbdir', action='store', dest='dbdir',
                    default=DEFAULT_DB_ALIAS, help='The directory to import from or export to '
                                                   'Defaults to the "default" database.'),
        make_option('--import', action='store_true',
            help='Import into database from csv files'),

        )


    def export_module(self, module_name, model_obj, dbdir):
        try:
            os.mkdir(os.path.join(dbdir, module_name))
        except:
            pass

        print model_obj.__name__

        outfile_path = os.path.join(dbdir, module_name, model_obj.__name__ + ".csv")

        model = model_obj
        outfile = open(outfile_path, 'wb')
        writer = csv.writer(outfile)
        headers = []
        header_type = {}
        for field in model._meta.fields:
            headers.append(field.name)
            header_type[field.name] = field
        writer.writerow(headers)
        print str(headers)
        line_count = 0
        for one_obj in model.objects.all():
            row = []
            skip_row = False
            for field in headers:
                try:
                    val = getattr(one_obj, field)
                except:
                    print "Skipping row "+str(one_obj.id)

                    skip_row = True
                    #exit()
                    break
                if val and header_type[field].__class__ == models.ForeignKey:
                    val = val.id
                elif callable(val):
                    val = val()
                elif type(val) == unicode:
                    val = val.encode("utf-8")
                row.append(val)
            if skip_row: continue

            writer.writerow(row)
            line_count += 1
            if line_count % 1000 == 1:
                sys.stdout.write(".")
                sys.stdout.flush()
        print ""
        outfile.close()

    def get_mappings(self, field_map, reader):
        mapping = []
        for i, heading in enumerate(reader.next()):
            for key in ((heading, heading.lower(),) if heading != heading.lower() else (heading,)):
                if field_map.has_key(key):
                    field = field_map[key]
                    key = check_fkey(key, field)
                    mapping.append('column%s=%s' % (i + 1, key))
        mappingstr = ','.join(mapping)
        mappings = make_mappings(mappingstr)
        return mappings

    def import_modules(self,dbdir):
        if not ALLOW_IMPORT:
            print "import disabled."
            return

        database = settings.COMMAND_DB
        if os.path.exists(dbdir) and os.path.isdir(dbdir):
            for module_full_name in os.listdir(dbdir):
                if not module_full_name in MODULES_TO_IMPORT: continue

                #
                # delete model data in an installed app
                #
                if CLEANUP_BEFORE_IMPORT:
                    from django.core.management import call_command

                    try:
                        call_command('reset', module_full_name.split('.')[1], database=database, interactive=False)
                    except:
                        pass
                for csv_file_name in os.listdir(os.path.join(dbdir, module_full_name)):
                    model_name = csv_file_name.split('.')[0]

                    app_label = module_full_name
                    if IMPORT_ONLY_THIS_MODEL and model_name != IMPORT_ONLY_THIS_MODEL:
                        continue
                    print "\nImporting into " + model_name
                    Model = getattr(import_module(app_label), model_name, None)
                    #print str(Model)

                    field_map = {}
                    for field in Model._meta.fields:
                        field_map[field.name] = field
                        if field.__class__ == models.ForeignKey:
                            field_map[field.name + "_id"] = field
                    infilepath = os.path.join(dbdir, module_full_name, model_name + ".csv")
                    infile = open(infilepath, 'r')
                    reader = csv.reader(infile)
                    mappings = self.get_mappings(field_map, reader)

                    counter = 0
                    bulk = []

                    for row in reader:
                        if counter % 1000 == 1:
                            sys.stdout.write(".")
                            sys.stdout.flush()
                        counter += 1
                        model_instance = Model()
                        #model_instance.csvimport_id = csvimportid
                        for (column, field, foreignkey) in mappings:
                            field_type = field_map.get(field).get_internal_type()
                            column = int(column) - 1

                            try:
                                row[column] = row[column].strip()
                            except Exception as e:
                                print e
                                pass

                            if foreignkey:
                                #print ""+str(column)+" foreignkey " + row[column]
                                #row[column] = insert_fkey(foreignkey, row[column], app_label)
                                pass

                            # Tidy up boolean data
                            if field_type in BOOLEAN:
                                row[column] = row[column] in BOOLEAN_TRUE

                            # Tidy up numeric data
                            if field_type in NUMERIC:
                                if not row[column]:
                                    row[column] = 0
                                else:
                                    try:
                                        row[column] = float(row[column])
                                    except:
                                        print ('Column %s = %s is not a number so is set to 0'\
                                               % (field, row[column]))
                                        row[column] = 0
                                if field_type in INTEGER:
                                    if row[column] > 9223372036854775807:
                                        print ('Column %s = %s more than the max integer 9223372036854775807'\
                                               % (field, row[column]))
                                    if str(row[column]).lower() in ('nan', 'inf', '+inf', '-inf'):
                                        print ('Column %s = %s is not an integer so is set to 0'\
                                               % (field, row[column]))
                                        row[column] = 0
                                    row[column] = int(row[column])
                                    if row[column] < 0 and field_type.startswith('Positive'):
                                        print('Column %s = %s, less than zero so set to 0'\
                                              % (field, row[column]))
                                        row[column] = 0
                            try:
                                if foreignkey:
                                    try:
                                        fkey = int(row[column])
                                    except:
                                        fkey = 0
                                    setattr(model_instance, field + "_id", fkey)
                                else:
                                    setattr(model_instance, field, row[column])

                            except Exception as e:
                                print e
                                try:
                                    row[column] = getattr(model_instance, field).to_python(row[column])
                                except Exception as e2:
                                    print e2
                                    try:
                                        row[column] = datetime(row[column])
                                    except:
                                        #row[column] = None
                                        print('Column %s failed %s' % (field, row[column]))
                                        exit()

                        try:
                            bulk.append(model_instance)
                        except Exception, err:
                            print('Exception found... %s Instance %s not saved.' % (err, counter))

                    if bulk:

                        pks = [obj.id for obj in bulk]

                        #print pks
                        dup = find_dups(pks)
                        if dup: print dup
                        Model.objects.bulk_create(bulk)




    def handle_noargs(self, **options):

        self._do_import = options.get('import', False)
        settings.COMMAND_DB = options.get('database', DEFAULT_DB_ALIAS)
        delete_all_plans = options.get('delete_all_plans', False)
        if delete_all_plans:
            return self.delete_all_plans()

        dbdir = options.get('dbdir', DEFAULT_DB_ALIAS)
        if self._do_import:
            return self.import_modules(dbdir)
        try:
            os.mkdir(dbdir)
        except:
            pass

        for module_full_pathname in MODULES_TO_EXPORT:
            print str(module_full_pathname)
            for name, obj in inspect.getmembers(sys.modules[module_full_pathname]):
                if inspect.isclass(obj) and is_django_model(obj) and obj.__module__ == module_full_pathname:
                    self.export_module(module_full_pathname, obj, dbdir)