django-rest-framework/rest_framework/compat.py

"""
The `compat` module provides support for backwards compatibility with older
versions of django/python, and compatibility wrappers around optional packages.
"""

# flake8: noqa
from __future__ import unicode_literals

import inspect

import django
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.db import connection, transaction
from django.forms import FilePathField as DjangoFilePathField
from django.test.client import FakePayload
from django.utils import six
from django.utils.encoding import force_text
from django.utils.six.moves.urllib.parse import urlparse as _urlparse

try:
    import importlib
except ImportError:
    from django.utils import importlib

def unicode_repr(instance):
    # Get the repr of an instance, but ensure it is a unicode string
    # on both python 3 (already the case) and 2 (not the case).
    if six.PY2:
        return repr(instance).decode('utf-8')
    return repr(instance)


def unicode_to_repr(value):
    # Coerce a unicode string to the correct repr return type, depending on
    # the Python version. We wrap all our `__repr__` implementations with
    # this and then use unicode throughout internally.
    if six.PY2:
        return value.encode('utf-8')
    return value


def unicode_http_header(value):
    # Coerce HTTP header value to unicode.
    if isinstance(value, six.binary_type):
        return value.decode('iso-8859-1')
    return value


def total_seconds(timedelta):
    # TimeDelta.total_seconds() is only available in Python 2.7
    if hasattr(timedelta, 'total_seconds'):
        return timedelta.total_seconds()
    else:
        return (timedelta.days * 86400.0) + float(timedelta.seconds) + (timedelta.microseconds / 1000000.0)


# OrderedDict only available in Python 2.7.
# This will always be the case in Django 1.7 and above, as these versions
# no longer support Python 2.6.
# For Django <= 1.6 and Python 2.6 fall back to SortedDict.
try:
    from collections import OrderedDict
except ImportError:
    from django.utils.datastructures import SortedDict as OrderedDict


# HttpResponseBase only exists from 1.5 onwards
try:
    from django.http.response import HttpResponseBase
except ImportError:
    from django.http import HttpResponse as HttpResponseBase


# contrib.postgres only supported from 1.8 onwards.
try:
    from django.contrib.postgres import fields as postgres_fields
except ImportError:
    postgres_fields = None


# request only provides `resolver_match` from 1.5 onwards.
def get_resolver_match(request):
    try:
        return request.resolver_match
    except AttributeError:
        # Django < 1.5
        from django.core.urlresolvers import resolve
        return resolve(request.path_info)


# django-filter is optional
try:
    import django_filters
except ImportError:
    django_filters = None

if django.VERSION >= (1, 6):
    def clean_manytomany_helptext(text):
        return text
else:
    # Up to version 1.5 many to many fields automatically suffix
    # the `help_text` attribute with hardcoded text.
    def clean_manytomany_helptext(text):
        if text.endswith(' Hold down "Control", or "Command" on a Mac, to select more than one.'):
            text = text[:-69]
        return text

# Django-guardian is optional. Import only if guardian is in INSTALLED_APPS
# Fixes (#1712). We keep the try/except for the test suite.
guardian = None
if 'guardian' in settings.INSTALLED_APPS:
    try:
        import guardian
        import guardian.shortcuts  # Fixes #1624
    except ImportError:
        pass


def get_model_name(model_cls):
    try:
        return model_cls._meta.model_name
    except AttributeError:
        # < 1.6 used module_name instead of model_name
        return model_cls._meta.module_name


# Support custom user models in Django 1.5+
try:
    from django.contrib.auth import get_user_model
except ImportError:
    from django.contrib.auth.models import User
    get_user_model = lambda: User


# View._allowed_methods only present from 1.5 onwards
if django.VERSION >= (1, 5):
    from django.views.generic import View
else:
    from django.views.generic import View as DjangoView

    class View(DjangoView):
        def _allowed_methods(self):
            return [m.upper() for m in self.http_method_names if hasattr(self, m)]


# MinValueValidator, MaxValueValidator et al. only accept `message` in 1.8+
if django.VERSION >= (1, 8):
    from django.core.validators import MinValueValidator, MaxValueValidator
    from django.core.validators import MinLengthValidator, MaxLengthValidator
else:
    from django.core.validators import MinValueValidator as DjangoMinValueValidator
    from django.core.validators import MaxValueValidator as DjangoMaxValueValidator
    from django.core.validators import MinLengthValidator as DjangoMinLengthValidator
    from django.core.validators import MaxLengthValidator as DjangoMaxLengthValidator

    class MinValueValidator(DjangoMinValueValidator):
        def __init__(self, *args, **kwargs):
            self.message = kwargs.pop('message', self.message)
            super(MinValueValidator, self).__init__(*args, **kwargs)

    class MaxValueValidator(DjangoMaxValueValidator):
        def __init__(self, *args, **kwargs):
            self.message = kwargs.pop('message', self.message)
            super(MaxValueValidator, self).__init__(*args, **kwargs)

    class MinLengthValidator(DjangoMinLengthValidator):
        def __init__(self, *args, **kwargs):
            self.message = kwargs.pop('message', self.message)
            super(MinLengthValidator, self).__init__(*args, **kwargs)

    class MaxLengthValidator(DjangoMaxLengthValidator):
        def __init__(self, *args, **kwargs):
            self.message = kwargs.pop('message', self.message)
            super(MaxLengthValidator, self).__init__(*args, **kwargs)


# URLValidator only accepts `message` in 1.6+
if django.VERSION >= (1, 6):
    from django.core.validators import URLValidator
else:
    from django.core.validators import URLValidator as DjangoURLValidator

    class URLValidator(DjangoURLValidator):
        def __init__(self, *args, **kwargs):
            self.message = kwargs.pop('message', self.message)
            super(URLValidator, self).__init__(*args, **kwargs)


# EmailValidator requires explicit regex prior to 1.6+
if django.VERSION >= (1, 6):
    from django.core.validators import EmailValidator
else:
    from django.core.validators import EmailValidator as DjangoEmailValidator
    from django.core.validators import email_re

    class EmailValidator(DjangoEmailValidator):
        def __init__(self, *args, **kwargs):
            super(EmailValidator, self).__init__(email_re, *args, **kwargs)


# PATCH method is not implemented by Django
if 'patch' not in View.http_method_names:
    View.http_method_names = View.http_method_names + ['patch']



try:
    # In 1.5 the test client uses force_bytes
    from django.utils.encoding import force_bytes as force_bytes_or_smart_bytes
except ImportError:
    # In 1.4 the test client just uses smart_str
    from django.utils.encoding import smart_str as force_bytes_or_smart_bytes


# RequestFactory only provides `generic` from 1.5 onwards
if django.VERSION >= (1, 5):
    from django.test.client import RequestFactory
else:
    from django.test.client import RequestFactory as DjangoRequestFactory

    class RequestFactory(DjangoRequestFactory):
        def generic(self, method, path,
                data='', content_type='application/octet-stream', **extra):
            parsed = _urlparse(path)
            data = force_bytes_or_smart_bytes(data, settings.DEFAULT_CHARSET)
            r = {
                'PATH_INFO': self._get_path(parsed),
                'QUERY_STRING': force_text(parsed[4]),
                'REQUEST_METHOD': six.text_type(method),
            }
            if data:
                r.update({
                    'CONTENT_LENGTH': len(data),
                    'CONTENT_TYPE': six.text_type(content_type),
                    'wsgi.input': FakePayload(data),
                })
            r.update(extra)
            return self.request(**r)


# Markdown is optional
try:
    import markdown

    def apply_markdown(text):
        """
        Simple wrapper around :func:`markdown.markdown` to set the base level
        of '#' style headers to <h2>.
        """

        extensions = ['headerid(level=2)']
        safe_mode = False
        md = markdown.Markdown(extensions=extensions, safe_mode=safe_mode)
        return md.convert(text)
except ImportError:
    apply_markdown = None


# `separators` argument to `json.dumps()` differs between 2.x and 3.x
# See: http://bugs.python.org/issue22767
if six.PY3:
    SHORT_SEPARATORS = (',', ':')
    LONG_SEPARATORS = (', ', ': ')
    INDENT_SEPARATORS = (',', ': ')
else:
    SHORT_SEPARATORS = (b',', b':')
    LONG_SEPARATORS = (b', ', b': ')
    INDENT_SEPARATORS = (b',', b': ')


if django.VERSION >= (1, 8):
    from django.db.models import DurationField
    from django.utils.dateparse import parse_duration
    from django.utils.duration import duration_string
else:
    DurationField = duration_string = parse_duration = None


def set_rollback():
    if hasattr(transaction, 'set_rollback'):
        if connection.settings_dict.get('ATOMIC_REQUESTS', False):
            # If running in >=1.6 then mark a rollback as required,
            # and allow it to be handled by Django.
            if connection.in_atomic_block:
                transaction.set_rollback(True)
    elif transaction.is_managed():
        # Otherwise handle it explicitly if in managed mode.
        if transaction.is_dirty():
            transaction.rollback()
        transaction.leave_transaction_management()
    else:
        # transaction not managed
        pass


def get_filepathfield(path, match=None, recursive=False, allow_files=True,
                      allow_folders=False, required=None):
    """Create proper Django FilePathField with allowed kwargs."""

    if django.VERSION < (1, 5):
        # django field doesn't have allow_folders, allow_files kwargs
        field = DjangoFilePathField(
            path, match=match, recursive=recursive, required=required
        )
    else:
        field = DjangoFilePathField(
            path, match=match, recursive=recursive, allow_files=allow_files,
            allow_folders=allow_folders, required=required
        )

    return field