Python Entrouvert

import os

import json

import glob

from django.conf import settings, UserSettingsHolder

from django.db import connection

from django.http import Http404

from django.contrib.contenttypes.models import ContentType

from tenant_schemas.utils import get_tenant_model, remove_www_and_dev, get_public_schema_name

SENTINEL = object()

class TenantNotFound(RuntimeError):

    pass

class TenantMiddleware(object):

    """

    This middleware should be placed at the very top of the middleware stack.

    Selects the proper database schema using the request host. Can fail in

    various ways which is better than corrupting or revealing data...

    """

    @classmethod

    def base(cls):

        return settings.TENANT_BASE

    @classmethod

    def hostname2schema(cls, hostname):

        '''Convert hostname to PostgreSQL schema name'''

        if hostname in getattr(settings, 'TENANT_MAPPING', {}):

            return settings.TENANT_MAPPING[hostname]

        return hostname.replace('.', '_').replace('-', '_')

    @classmethod

    def get_tenant_by_hostname(cls, hostname):

        '''Retrieve a tenant object for this hostname'''

        if not os.path.exists(os.path.join(cls.base(), hostname)):

            raise TenantNotFound

        schema = cls.hostname2schema(hostname)

        return get_tenant_model()(schema_name=schema, domain_url=hostname)

    @classmethod

    def get_tenants(cls):

        self = cls()

        for path in glob.glob(os.path.join(cls.base(), '*')):

            hostname = os.path.basename(path)

            yield get_tenant_model()(

                    schema_name=self.hostname2schema(hostname),

                    domain_url=hostname)

    def process_request(self, request):

        # connection needs first to be at the public schema, as this is where the

        # tenant informations are saved

        connection.set_schema_to_public()

        hostname_without_port = remove_www_and_dev(request.get_host().split(':')[0])

        try:

            request.tenant = self.get_tenant_by_hostname(hostname_without_port)

        except TenantNotFound:

            raise Http404

        connection.set_tenant(request.tenant)

        # content type can no longer be cached as public and tenant schemas have different

        # models. if someone wants to change this, the cache needs to be separated between

        # public and shared schemas. if this cache isn't cleared, this can cause permission

        # problems. for example, on public, a particular model has id 14, but on the tenants

        # it has the id 15. if 14 is cached instead of 15, the permissions for the wrong

        # model will be fetched.

        ContentType.objects.clear_cache()

        # do we have a public-specific token?

        if hasattr(settings, 'PUBLIC_SCHEMA_URLCONF') and request.tenant.schema_name == get_public_schema_name():

            request.urlconf = settings.PUBLIC_SCHEMA_URLCONF

class TenantSettingBaseMiddleware(object):

    '''Base middleware classe for loading settings based on tenants

       Child classes MUST override the load_tenant_settings() method.

    '''

    def __init__(self, *args, **kwargs):

        self.tenants_settings = {}

    def get_tenant_settings(self, wrapped, tenant):

        '''Get last loaded settings for tenant, try to update it by loading

           settings again is last loading time is less recent thant settings data

           store. Compare with last modification time is done in the

           load_tenant_settings() method.

        '''

        tenant_settings, last_time = self.tenants_settings.get(tenant.schema_name, (None,None))

        if tenant_settings is None:

            tenant_settings = UserSettingsHolder(wrapped)

        tenant_settings, last_time = self.load_tenant_settings(wrapped, tenant, tenant_settings, last_time)

        self.tenants_settings[tenant.schema_name] = tenant_settings, last_time

        return tenant_settings

    def load_tenant_settings(self, wrapped, tenant, tenant_settings, last_time):

        '''Load tenant settings into tenant_settings object, eventually skip if

           last_time is more recent than last update time for settings and return

           the new value for tenant_settings and last_time'''

        raise NotImplemented

    def process_request(self, request):

        if not hasattr(request, '_old_settings_wrapped'):

            request._old_settings_wrapped = []

        request._old_settings_wrapped.append(settings._wrapped)

        settings._wrapped = self.get_tenant_settings(settings._wrapped, request.tenant)

    def process_response(self, request, response):

        if hasattr(request, '_old_settings_wrapped') and request._old_settings_wrapped:

            settings._wrapped = request._old_settings_wrapped.pop()

        return response

class FileBasedTenantSettingBaseMiddleware(TenantSettingBaseMiddleware):

    FILENAME = None

    def load_tenant_settings(self, wrapped, tenant, tenant_settings, last_time):

        path = os.path.join(settings.TENANT_BASE, tenant.domain_url, self.FILENAME)

        try:

            new_time = os.stat(path).st_mtime

        except OSError:

            # file was removed

            if not last_time is None:

                return UserSettingsHolder(wrapped), None

        else:

            if last_time is None or new_time >= last_time:

                # file is new

                tenant_settings = UserSettingsHolder(wrapped)

                self.load_file(tenant_settings, path)

                return tenant_settings, new_time

        # nothing has changed

        return tenant_settings, last_time

class JSONSettingsMiddleware(FileBasedTenantSettingBaseMiddleware):

    '''Load settings from a JSON file whose path is given by:

            os.path.join(settings.TENANT_BASE % schema_name, 'settings.json')

       The JSON file must be a dictionnary whose key/value will override

       current settings.

    '''

    FILENAME = 'settings.json'

    def load_file(sef, tenant_settings, path):

        with file(path) as f:

            json_settings = json.load(f)

            for key in json_settings:

                setattr(tenant_settings, key, json_settings[key])

class DictAdapter(dict):

    '''Give dict interface to plain objects'''

    def __init__(self, wrapped):

        self.wrapped = wrapped

    def __setitem__(self, key, value):

        setattr(self.wrapped, key, value)

    def __getitem__(self, key):

        try:

            return getattr(self.wrapped, key)

        except AttributeError:

            raise KeyError

class PythonSettingsMiddleware(FileBasedTenantSettingBaseMiddleware):

    '''Load settings from a file whose path is given by:

            os.path.join(settings.TENANT_BASE % schema_name, 'settings.py')

       The file is executed in the same context as the classic settings file

       using execfile.

    '''

    FILENAME = 'settings.py'

    def load_file(self, tenant_settings, path):

        execfile(path, DictAdapter(tenant_settings))