Source code for dash.base

"""
All `uids` are supposed to be pythonic function names (see PEP http://www.python.org/dev/peps/pep-0008/#function-names).
"""

__all__ = ('BaseDashboardLayout', 'BaseDashboardPlaceholder', 'BaseDashboardPlugin', \
           'BaseDashboardPluginWidget', 'layout_registry', 'plugin_widget_registry', \
           'get_registered_plugins', 'get_registered_plugin_uids', 'validate_plugin_uid', \
           'get_registered_layouts', 'get_registered_layout_uids', 'get_layout', \
           'validate_placeholder_uid', 'plugin_registry', 'ensure_autodiscover', \
           'DashboardPluginFormBase', 'collect_widget_media')

import uuid
import json

from six import text_type

from django.forms import ModelForm
from django.forms.util import ErrorList
from django.http import Http404
from django.template.loader import render_to_string
from django.utils.encoding import force_text

from dash.discover import autodiscover
from dash.exceptions import LayoutDoesNotExist
from dash.settings import ACTIVE_LAYOUT, LAYOUT_CELL_UNITS, DEBUG
from dash.settings import DEFAULT_PLACEHOLDER_VIEW_TEMPLATE_NAME, DEFAULT_PLACEHOLDER_EDIT_TEMPLATE_NAME
from dash.exceptions import InvalidRegistryItemType

import logging
logger = logging.getLogger(__name__)

_ = lambda s: s

[docs]class DashboardPluginFormBase(object):
    """
    Not a form actually. Defined for magic only.

    :property iterable plugin_data_fields: Fields to get when calling the ``get_plugin_data`` method.

    :example:

        >>> plugin_data_fields = (
        >>>    ('name', ''),
        >>>    ('active': False)
        >>> )
    """
    plugin_data_fields = None

    def _get_plugin_data(self, fields):
        """
        Gets plugin data.

        :param iterable fields: List of tuples to iterate.
        :return string: JSON dumpled string.
        """
        data = {}

        for field, default_value in fields:
            data.update({field: self.cleaned_data.get(field)})
        return json.dumps(data)

[docs]    def get_plugin_data(self):
        """
        Data that would be saved in the ``plugin_data`` field of the ``dash.models.DashboardEntry``
        subclassed model.
        """
        if self.plugin_data_fields:
            return self._get_plugin_data(self.plugin_data_fields)

[docs]    def save_plugin_data(self):
        """
        Dummy, but necessary.
        """


[docs]class BaseDashboardLayout(object):
    """
    Base layout.

    Layouts consist of placeholders.

    :Properties:
        - `uid` (str): Layout unique identifier (globally).
        - `name` (str): Layout name.
        - `description` (str): Layout description.
        - `placeholders` (iterable): Iterable (list, tuple or set) of `dash.base.BaseDashboardPlaceholder`
           subclasses.
        - `view_template_name` (str): Temlate name used to render the layout (view).
        - `edit_template_name` (str): Template named used to render the layout (edit).
        - `html_classes` (str): Extra HTML class that layout should get.
        - `cell_units` (str):
        - `media_css` (list): List all specific stylesheets.
        - `media_js` (list): List all specific javascripts.
    """
    uid = None
    name = None
    description = None
    placeholders = []
    view_template_name = None
    view_template_name_ajax = None
    edit_template_name = None
    edit_template_name_ajax = None
    html_classes = []
    cell_units = None # Most likely, it makes sense to define this on a layout level. Think of it.
    media_css = []
    media_js = []

    def __init__(self, user=None):
        """
        :param django.contrib.auth.models.User user:
        """
        assert self.uid
        assert self.name
        assert self.view_template_name
        assert self.edit_template_name
        assert self.placeholders
        assert self.cell_units and self.cell_units in LAYOUT_CELL_UNITS
        assert isinstance(self.media_js, (list, tuple))
        assert isinstance(self.media_css, (list, tuple))

        if isinstance(self.media_js, tuple):
            self.media_js = list(self.media_js)

        if isinstance(self.media_css, tuple):
            self.media_css = list(self.media_css)

        self.placeholders_dict = {}
        self.placeholder_uids = []
        for placeholder in self.placeholders:
            self.placeholders_dict.update({placeholder.uid: placeholder})
            self.placeholder_uids.append(placeholder.uid)

        self.user = user
        self.widget_media_js = []
        self.widget_media_css = []

[docs]    def get_view_template_name(self, request=None):
        if not self.view_template_name_ajax:
            return self.view_template_name
        elif request and request.is_ajax():
            return self.view_template_name_ajax
        else:
            return self.view_template_name

[docs]    def get_edit_template_name(self, request=None):
        if not self.edit_template_name_ajax:
            return self.edit_template_name
        elif request and request.is_ajax():
            return self.edit_template_name_ajax
        else:
            return self.edit_template_name

[docs]    def get_placeholder(self, uid, default=None):
        return self.placeholders_dict.get(uid, default)

[docs]    def get_placeholders(self, request=None):
        """
        Gets the list of placeholders registered for the layout.

        :param django.http.HttpRequest request:
        :return itetable: List of placeholder classes. Override in your layout if you need a custom behaviour.
        """
        return self.placeholders

[docs]    def get_placeholder_uids(self, request=None):
        """
        Gets the list of placeholder uids.

        :param django.http.HttpRequest request:
        :return list:
        """
        uids = []
        for placeholder in self.placeholders:
            uids.append(placeholder.uid)
        return uids

[docs]    def collect_widget_media(self, dashboard_entries):
        """
        Collects the widget media files.

        :param iterable dashboard_entries: Iterable of ``dash.models.DashboardEntry`` instances.
        :return list:
        """
        widget_media = collect_widget_media(dashboard_entries)
        #logger.debug(widget_media)
        if widget_media:
            self.widget_media_js, self.widget_media_css = widget_media['js'], widget_media['css']

[docs]    def get_media_css(self):
        """
        Gets all CSS media files (for the layout + plugins).

        :return list:
        """
        media_css = self.media_css[:]
        if self.widget_media_css:
            media_css += self.widget_media_css

        media_css = list(set(media_css))

        #logger.debug(media_css)

        return media_css

[docs]    def get_media_js(self):
        """
        Gets all JavaScript media files (for the layout + plugins).

        :return list:
        """
        media_js = self.media_js[:]
        if self.widget_media_js:
            media_js += self.widget_media_js

        media_js = list(set(media_js))

        #logger.debug(media_js)

        return media_js

[docs]    def get_grouped_dashboard_entries(self, dashboard_entries):
        """
        Gets dashboard entries grouped by placeholder.

        :param iterable dashboard_entries: Iterable of `dash.models.DashboardEntry` objects.
        :return list:
        """
        entries = {}

        if not dashboard_entries:
            return entries

        for dashboard_entry in dashboard_entries:
            if not dashboard_entry.placeholder_uid in entries:
                entries[dashboard_entry.placeholder_uid] = []
            entries[dashboard_entry.placeholder_uid].append(dashboard_entry)

        return entries

[docs]    def get_placeholder_instances(self, dashboard_entries=None, workspace=None, request=None):
        """
        Gets placeholder instances.

        :param iterable dashboard_entries: Iterable of `dash.models.DashboardEntry` objects.
        :param django.http.HttpRequest request:
        :return list: List of `dash.base.BaseDashboardPlaceholder` subclassed instances.
        """
        entries = self.get_grouped_dashboard_entries(dashboard_entries)

        placeholder_instances = []

        for placeholder_cls in self.get_placeholders(request):

            placeholder = placeholder_cls(self)
            placeholder.request = request
            placeholder.workspace = workspace
            if entries:
                placeholder.dashboard_entries = entries.get(placeholder_cls.uid, None)

            placeholder_instances.append(placeholder)

        return placeholder_instances

    @property
[docs]    def primary_html_class(self):
        return 'layout-{0}'.format(self.uid)

    @property
[docs]    def html_class(self):
        """
        Class used in the HTML.

        :return str:
        """
        return '{0} {1}'.format(self.primary_html_class, ' '.join(self.html_classes))

[docs]    def get_css(self, placeholders):
        """
        Gets placeholder specific css.

        :param iterable placeholders: Iterable of `dash.base.BaseDashboardPlaceholder` subclassed instances.
        :return str:
        """
        css = []
        for placeholder in placeholders:
            css.append(placeholder.css)
        return '\n'.join(css)

[docs]    def render_for_view(self, dashboard_entries=None, workspace=None, request=None):
        """
        Renders the layout.

        :param iterable dashboard_entries:
        :param str workspace: Current workspace.
        :param django.http.HttpRequest request:
        :return str:
        """
        placeholders = self.get_placeholder_instances(dashboard_entries, workspace, request)
        context = {
            'placeholders': placeholders,
            'request': request,
            'css': self.get_css(placeholders)
        }
        return render_to_string(self.get_view_template_name(request), context)

[docs]    def render_for_edit(self, dashboard_entries=None, workspace=None, request=None):
        """
        Renders the layout.

        :param iterable dashboard_entries:
        :param str workspace: Current workspace.
        :param django.http.HttpRequest request:
        :return str:
        """
        placeholders = self.get_placeholder_instances(dashboard_entries, workspace, request)
        context = {'placeholders': placeholders, 'request': request, 'css':  self.get_css(placeholders)}
        return render_to_string(self.get_edit_template_name(request), context)


[docs]class BaseDashboardPlaceholder(object):
    """
    Base placeholder.

    :Properties:
        - `uid` (str): Unique identifier (shouldn't repeat within a single layout).
    """
    uid = None
    cols = None #1
    rows = None #8
    cell_width = None #100
    cell_height = None #100
    view_template_name = ''
    edit_template_name = ''
    html_classes = []

    def __init__(self, layout):
        assert self.uid
        assert self.rows
        assert self.cols
        assert self.cell_width
        assert self.cell_height

        self.layout = layout
        self.dashboard_entries = None
        self.request = None

    @property
[docs]    def cell_units(self):
        return self.layout.cell_units

    @property
[docs]    def html_id(self):
        """
        ID used in the HTML. Unique.

        :return str:
        """
        return 'id_{0}'.format(self.uid)

    @property
[docs]    def primary_html_class(self):
        return 'placeholder-{0}'.format(self.uid)

    @property
[docs]    def html_class(self):
        """
        Class used in the HTML.

        :return str:
        """
        return '{0} {1}'.format(self.primary_html_class, ' '.join(self.html_classes))

[docs]    def get_view_template_name(self):
        return self.view_template_name if self.view_template_name else DEFAULT_PLACEHOLDER_VIEW_TEMPLATE_NAME

[docs]    def get_edit_template_name(self):
        return self.edit_template_name if self.view_template_name else DEFAULT_PLACEHOLDER_EDIT_TEMPLATE_NAME

[docs]    def load_dashboard_entries(self, dashboard_entries=None):
        """
        Feed the dashboard entries to the layout for rendering later.

        :param iterable dashboard_entries: Iterable of `dash.models.DashboardEntry` objects.
        """
        self.dashboard_entries = dashboard_entries

[docs]    def render_for_view(self):
        """
        Renders the placeholder for view mode.

        :return str:
        """
        context = {
            'placeholder': self,
            'dashboard_entries': self.dashboard_entries,
            'request': self.request,
            'workspace': self.workspace
        }
        return render_to_string(self.get_view_template_name(), context)

    def _generate_widget_cells(self):
        """
        Generates widget cells. Returns a list of tuples, where the first element represents the cell class
        and the second element represents the cell position.

        :param str workspace: Current workspace slug.
        :param django.http.HttpRequest request:
        :return list:
        """
        empty_cells = []
        position = 1
        for row in range(1, self.rows + 1):
            for col in range(1, self.cols + 1):
                empty_cells.append(('col-{0} row-{1}'.format(col, row), position))
                position += 1
        return empty_cells

[docs]    def render_for_edit(self):
        """
        Renders the placeholder for edit mode.

        :param str workspace: Current workspace slug.
        :param django.http.HttpRequest request:
        :return str:
        """
        context = {
            'placeholder': self,
            'dashboard_entries': self.dashboard_entries,
            'request': self.request,
            'workspace': self.workspace,
            'widget_cells': self._generate_widget_cells()
        }
        return render_to_string(self.get_edit_template_name(), context)

    @property
[docs]    def css(self):
        """
        CSS styles for the placeholders and plugins. The placeholder dimensions as well as columns sizes,
        should be handled here. Since we are in a placeholder and a placeholder has a defined number of
        rows and columns and each reneder has just a fixed amount of rows and columns defined, we can
        render the top left corners generic css classes.

        Cells do NOT have margins or paddings. This is essential (since all the plugins are positioned
        absolutely). If you want to have padding in your plugin widget, specify the `plugin-content-wrapper`
        class style in your specific layout/theme.

        :example:

            .placeholder .plugin .plugin-content-wrapper {
                padding: 5px;
            }

        :return str:
        """
        def placeholder_width():
            """
            Placeholder width.

            :return str:
            """
            return '{0}{1}'.format(self.cols * self.cell_width, self.cell_units)

        def placeholder_height():
            """
            Placeholder height.

            :return str:
            """
            return '{0}{1}'.format(self.rows * self.cell_height, self.cell_units)

        def plugin_width():
            """
            Default width of a plugin widget (1 cell).

            :return str:
            """
            return '{0}{1}'.format(self.cell_width, self.cell_units)

        def plugin_height():
            """
            Default height of a plugin widget (1 cell).

            :return str:
            """
            return '{0}{1}'.format(self.cell_height, self.cell_units)

        def plugin_positions():
            """
            Plugin positions depending on the row and cell occupied. All plugins are positioned absolutely.
            Based on the row, we use `margin-top` and `margin-left` to position a plugin.

            ..:Used CSS classes:
                - `row-1`, `row-2`, etc.
                - `col-1`, `col-2`, etc.

            :return str:
            """
            positions = []
            for row_num in range(0, self.rows):
                s = """
                    .placeholder.{placeholder_class} .empty-widget-cell.row-{row_num},
                    .placeholder.{placeholder_class} .plugin.row-{row_num} {{
                        margin-top: {top};
                    }}
                    """.format(
                    placeholder_class = self.primary_html_class,
                    row_num = (row_num + 1),
                    top = '{0}{1}'.format(self.cell_height * row_num, self.cell_units)
                )
                positions.append(s)

            for col_num in range(0, self.cols):
                s = """
                    .placeholder.{placeholder_class} .empty-widget-cell.col-{col_num},
                    .placeholder.{placeholder_class} .plugin.col-{col_num} {{
                        margin-left: {left};
                    }}
                    """.format(
                    placeholder_class = self.primary_html_class,
                    col_num = (col_num + 1),
                    left = '{0}{1}'.format(self.cell_width * col_num, self.cell_units)
                )
                positions.append(s)

            return '\n'.join(positions)

        def plugin_sizes():
            """
            Plugin size based on its' `rows` and `cols` properties.
                
            ..:Used CSS classes:
                - `width-1`, `width-2`, etc.
                - `height-1`, `height-2`, etc.

            :return str:
            """
            sizes = []
            for row_num in range(0, self.rows):
                s = """
                    .placeholder.{placeholder_class} .plugin.height-{row_num} {{
                        height: {height};
                    }}
                    """.format(
                    placeholder_class = self.primary_html_class,
                    row_num = (row_num + 1),
                    height = '{0}{1}'.format(self.cell_height * (row_num + 1), self.cell_units)
                )
                sizes.append(s)

            for col_num in range(0, self.cols):
                s = """
                    .placeholder.{placeholder_class} .plugin.width-{col_num} {{
                        width: {width};
                    }}
                    """.format(
                        placeholder_class = self.primary_html_class,
                        col_num = (col_num + 1),
                        width = '{0}{1}'.format(self.cell_width * (col_num + 1), self.cell_units)
                    )
                sizes.append(s)

            return '\n'.join(sizes)


        def empty_cell_size():
            """
            CSS for empty cell size.
            """
            s = """
            .placeholder.{placeholder_class} .empty-widget-cell {{
                width: {width};
                height: {height};
                line-height: {height};
            }}
            """.format(
                placeholder_class = self.primary_html_class,
                width = '{0}{1}'.format(self.cell_width, self.cell_units),
                height = '{0}{1}'.format(self.cell_height, self.cell_units)
            )
            return s

        css = """
        .placeholder.{placeholder_class} {{
            width: {placeholder_width};
            height: {placeholder_height};
        }}

        .placeholder.{placeholder_class} .plugin {{
            width: {plugin_width};
            height: {plugin_height};
        }}

        {plugin_positions}

        {plugin_sizes}

        {empty_cell_sizes}
        """.format(
            placeholder_class = self.primary_html_class,
            placeholder_width = placeholder_width(),
            placeholder_height = placeholder_height(),
            plugin_width = plugin_width(),
            plugin_height = plugin_height(),
            plugin_positions = plugin_positions(),
            plugin_sizes = plugin_sizes(),
            empty_cell_sizes = empty_cell_size()
        )

        return css


class DashboardPluginDataStorage(object):
    """
    Storage for plugin data.
    """


[docs]class BaseDashboardPlugin(object):
    """
    Base dashboard plugin from which every plugin should inherit.

    :Properties:
        - `uid` (str): Plugin uid (obligatory). Example value: 'dummy', 'wysiwyg', 'news'.
        - `name` (str): Plugin name (obligatory). Example value: 'Dummy plugin',
          'WYSIWYG', 'Latest news'.
        - `description` (str): Plugin decription (optional). Example value: 'Dummy plugin used just for testing'.
        - `help_text` (str): Plugin help text (optional). This text would be shown in
            ``dash.views.add_dashboard_entry`` and ``dash.views.edit_dashboard_entry`` views.
        - `form`: Plugin form (optional). A subclass of ``django.forms.Form``. Should be given
          in case plugin is configurable.
        - `add_form_template` (str) (optional): Add form template (optional). If given, overrides the
          `dash.views.add_dashboard_entry` default template.
        - `edit_form_template` (str): Edit form template (optional). If given, overrides the
          `dash.views.edit_dashboard_entry` default template.
        - `html_classes` (list): List of extra HTML classes for the plugin.
        - `group` (str): Plugin are grouped under the specified group. Override in your plugin if necessary.
    """
    uid = None
    name = None
    description = None
    help_text = None
    form = None
    add_form_template = None
    edit_form_template = None
    html_classes = []
    group = _("General")

    def __init__(self, layout_uid, placeholder_uid, workspace=None, user=None, position=None):
        """
        :param str placeholder_uid: Unique identifier of plugin placeholder (layout.placeholder).
        :param dash.models.DashboardWorkspace workspace: Plugin workspace.
        :param django.contrib.auth.models.User user: Plugin owner.
        """
        # Making sure all necessary properties are defined.
        try:
            assert self.uid
            assert self.name
        except Exception as e:
            raise NotImplementedError(
                "You should define `uid` and `name` properties in your `{0}.{1}` class.".format(
                    self.__class__.__module__, self.__class__.__name__
                    )
                )

        layout_cls = layout_registry.get(layout_uid, None)
        self.layout = layout_cls() if layout_cls else None

        placeholder_cls = self.layout.get_placeholder(placeholder_uid)
        self.placeholder = placeholder_cls(self.layout) if placeholder_cls else None

        if not (self.layout and self.placeholder):
            raise Exception(
                "Invalid placeholder value {0} in your `{1}.{2}` class.".format(
                    placeholder_uid, self.__class__.__module__, self.__class__.__name__
                    )
                )

        self.layout_uid = layout_uid
        self.placeholder_uid = placeholder_uid
        self.workspace = workspace
        self.user = user
        self.position = position

        # Some initial values
        self.request = None

        self.data = DashboardPluginDataStorage()

        self._html_id = 'p{0}'.format(uuid.uuid4())

    @property
[docs]    def html_id(self):
        return self._html_id

[docs]    def get_position(self):
        """
        Gets the exact position of the plugin widget in the placeholder (row number, col number).

        :return tuple: Tuple of row and col numbers.
        """
        col = self.position % self.placeholder.cols
        row = int(self.position / self.placeholder.cols) + (1 if col > 0 else 0)
        if col == 0:
            col = self.placeholder.cols

        return (row, col)

    @property # Comment the @property if something goes wrong.
[docs]    def html_class(self):
        """
        A massive work on positioning the plugin and having it to be displayed in a given width is
        done here. We should be getting the plugin widget for the plugin given and based on its'
        properties (static!) as well as on plugin position (which we have from model), we can show
        the plugin with the exact class.
        """
        try:
            widget = self.get_widget()

            html_class = ['plugin-{0} {1} {2}'.format(self.uid, widget.html_class, ' '.join(self.html_classes))]

            html_class.append('width-{0}'.format(widget.cols))
            html_class.append('height-{0}'.format(widget.rows))

            row, col = self.get_position()
            html_class.append('row-{0}'.format(row))
            html_class.append('col-{0}'.format(col))

            return ' '.join(html_class)
        except Exception as e:
            logger.debug(str(e))

[docs]    def process(self, plugin_data=None, fetch_related_data=False):
        """
        Init plugin with data.
        """
        try:
            # Calling pre-processor.
            self.pre_processor()

            if plugin_data:
                try:
                    # Trying to load the plugin data to JSON.
                    plugin_data = json.loads(plugin_data)

                    # If a valid JSON object, feed it to our plugin and process the data. The
                    # ``process_data`` method should be defined in your subclassed plugin class.
                    if plugin_data:
                        self.load_plugin_data(plugin_data)

                        self.process_plugin_data(fetch_related_data=fetch_related_data)
                except Exception as e:
                    if DEBUG:
                        logger.debug(str(e))

            # Calling the post processor.
            self.post_processor()

            return self
        except Exception as e:
            if DEBUG:
                logger.debug(str(e))

[docs]    def load_plugin_data(self, plugin_data):
        """
        Loads the plugin data saved in ``dash.models.DashboardEntry``. Plugin data is saved in JSON
        string.

        :param str plugin_data: JSON string with plugin data.
        """
        self.plugin_data = plugin_data

    def _process_plugin_data(self, fields, fetch_related_data=False):
        """
        Process the plugin data. Override if need customisations.

        Beware, this is not always called.
        """
        for field, default_value in fields:
            try:
                setattr(self.data, field, self.plugin_data.get(field, default_value))
            except Exception as e:
                setattr(self.data, field, default_value)

[docs]    def process_plugin_data(self, fetch_related_data=False):
        """
        Processes the plugin data.
        """
        form = self.get_form()

        return self._process_plugin_data(form.plugin_data_fields, fetch_related_data=fetch_related_data)

    def _get_plugin_form_data(self, fields):
        """
        Gets plugin data.

        :param iterable fields: List of tuples to iterate.
        :return dict:
        """
        form_data = {}
        for field, default_value in fields:
            try:
                form_data.update({field: self.plugin_data.get(field, default_value)})
            except Exception as e:
                if DEBUG:
                    logger.debug(e)
        return form_data

[docs]    def get_plugin_form_data(self):
        """
        Fed as ``initial`` argument to the plugin form when initialising the instance for adding or
        editing the plugin. Override in your plugin class if you need customisations.
        """
        form = self.get_form()

        return self._get_plugin_form_data(form.plugin_data_fields)

[docs]    def get_instance(self):
        return None

[docs]    def get_form(self):
        """
        Get the plugin form class. Override this method in your subclassed ``dash.base.DashboardPlugin``
        class when you need your plugin setup to vary depending on the placeholder, workspace, user or
        request given. By default returns the value of the ``form`` attribute defined in your plugin.

        :return django.forms.Form|django.forms.ModelForm: Subclass of ``django.forms.Form`` or
            ``django.forms.ModelForm``.
        """
        return self.form

[docs]    def get_initialised_create_form(self, data=None, files=None):
        """
        Used ``dash.views.add_dashboard_entry`` view to gets initialised form for object to be created.
        """
        plugin_form = self.get_form()
        if plugin_form:
            try:
                plugin_form = self.get_form()
                if plugin_form:
                    return plugin_form(data=data, files=files)
            except Exception as e:
                if DEBUG:
                    logger.debug(e)
                raise Http404(e)

[docs]    def get_initialised_create_form_or_404(self, data=None, files=None):
        """
        Same as ``get_initialised_create_form`` but raises ``django.http.Http404`` on errors.
        """
        plugin_form = self.get_form()
        if plugin_form:
            try:
                return self.get_initialised_create_form(data=data, files=files)
            except Exception as e:
                if DEBUG:
                    logger.debug(e)
                raise Http404(e)

[docs]    def get_initialised_edit_form(self, data=None, files=None, auto_id='id_%s', prefix=None, \
                                  initial=None, error_class=ErrorList, label_suffix=':', \
                                  empty_permitted=False, instance=None):
        """
        Used in ``dash.views.edit_dashboard_entry`` view.
        """
        plugin_form = self.get_form()
        if plugin_form:
            kwargs = {
                'data': data,
                'files': files,
                'auto_id': auto_id,
                'prefix': prefix,
                'initial': initial,
                'error_class': error_class,
                'label_suffix': label_suffix,
                'empty_permitted': empty_permitted
            }
            if issubclass(plugin_form, ModelForm):
                kwargs.update({'instance': instance})
            return plugin_form(**kwargs)

[docs]    def get_initialised_edit_form_or_404(self, data=None, files=None, auto_id='id_%s', prefix=None, \
                                         error_class=ErrorList, label_suffix=':', empty_permitted=False):
        """
        Same as ``get_initialised_edit_form`` but raises ``django.http.Http404`` on errors.
        """
        plugin_form = self.get_form()
        if plugin_form:
            try:
                return self.get_initialised_edit_form(
                    data=data, files=files, auto_id=auto_id, prefix=prefix,
                    initial=self.get_plugin_form_data(), error_class=error_class,
                    label_suffix=label_suffix, empty_permitted=empty_permitted,
                    instance=self.get_instance()
                    )
            except Exception as e:
                if DEBUG:
                    logger.debug(e)
                raise Http404(e)

[docs]    def get_widget(self, request=None, as_instance=False):
        """
        Gets the plugin widget.

        :param django.http.HttpRequest request:
        :param bool as_instance:
        :return mixed: Subclass of `dash.base.BaseDashboardPluginWidget` or instance of subclassed
            `dash.base.BaseDashboardPluginWidget` object.
        """
        widget_cls = plugin_widget_registry.get(
            PluginWidgetRegistry.namify(self.layout.uid, self.placeholder.uid, self.uid)
            )

        if not as_instance:
            return widget_cls
        elif widget_cls:
            widget = widget_cls(self)
            return widget

[docs]    def render(self, request=None):
        """
        Renders the plugin HTML (for dashboard workspace).

        :param django.http.HttpRequest request:
        :return str:
        """
        widget_cls = self.get_widget()

        if widget_cls:
            widget = widget_cls(self)

            render = widget.render(request=request)
            return render or ''
        elif DEBUG:
            logger.debug("No widget defined for {0}.{1}.{2}".format(self.layout.uid, self.placeholder.uid, self.uid))

[docs]    def update_plugin_data(self, dashboard_entry):
        """
        Used in ``dash.management.commands.dash_update_plugin_data``.

        Some plugins would contain data fetched from various sources (models, remote data). Since dashboard 
        entries are by definition loaded extremely much, you are advised to store as much data as possible in
        ``plugin_data`` field of ``dash.models.DashboardEntry``. Some externally fetched data becomes invalid
        after some time and needs updating. For that purpose, in case if your plugin needs that, redefine this
        method in your plugin. If you need your data to be periodically updated, add a cron-job which would 
        run ``dash_update_plugin_data`` management command (see
        ``dash.management.commands.dash_update_plugin_data`` module).

        :param dash.models.DashboardEntry: Instance of ``dash.models.DashboardEntry``.
        """
        pass

[docs]    def delete_plugin_data(self):
        """
        Used in ``dash.views.delete_dashboard_entry``. Fired automatically, when ``dash.models.DashboardEntry``
        object is about to be deleted. Make use of it if your plugin creates database records that are not
        monitored externally but by dash only.
        """

[docs]    def pre_processor(self):
        """
        Redefine in your subclassed plugin when necessary.

        Pre process plugin data (before rendering). This method is being called before the data has been
        loaded into the plugin.
        
        Note, that request (django.http.HttpRequest) is available (self.request).
        """

[docs]    def post_processor(self):
        """
        Redefine in your subclassed plugin when necessary.

        Post process plugin data here (before rendering). This methid is being called after the data has been
        loaded into the plugin.
        
        Note, that request (django.http.HttpRequest) is available (self.request).
        """

class MetaBaseDashboardPluginWidget(type):
    """
    Meta class for ``dash.base.BaseDashboardPluginWidget``.
    """
    @property
    def html_class(cls):
        """
        HTML class of the ``dash.base.BaseDashboardPluginWidget``.

        :return str:
        """
        return ' '.join(cls.html_classes)


class classproperty(property):
    def __get__(self, cls, owner):
        return classmethod(self.fget).__get__(None, owner)()


[docs]class BaseDashboardPluginWidget(object):
    """
    Base plugin widget.

    So, if we would want to register a plugin widget (renderer) for some layout, we would first define the
    plugin widget and then just write:

        >>> plugin_widget_registry.register(DummyPluginWidget)

    Plugin widget is always being registered for a placeholder. Placeholder in its' turn has number of
    rows and columns. Since we register each widget for a (layout, placeholder, plugin) combination
    separately, it fits the needs and requirements perfectly. In that way we are able to tell, wheither
    plugin has a widget available and actually valid (qua dimensions) for the placeholder. Plugin is
    just data. Nothing more. Widget operates with that data. Thus, widget has number of rows and
    columns it occupies in the placeholder registered. By default, number of rows and columns is set to
    1, which means that a plugin occupies just 1 cell. But, certainly, there can be plugins that occupy
    more space in a placeholder.
    """
    #__metaclass__ = MetaBaseDashboardPluginWidget

    layout_uid = None
    placeholder_uid = None
    plugin_uid = None
    cols = 1
    rows = 1
    html_classes = []
    media_js = []
    media_css = []

    def __init__(self, plugin):
        assert self.layout_uid and self.layout_uid == plugin.layout.uid
        assert self.placeholder_uid and self.placeholder_uid in plugin.layout.placeholder_uids
        assert self.plugin_uid and self.plugin_uid in get_registered_plugin_uids()
        assert hasattr(self, 'render') and callable(self.render)
        assert self.cols
        assert self.rows
        assert isinstance(self.media_js, (list, tuple))
        assert isinstance(self.media_css, (list, tuple))

        if isinstance(self.media_js, tuple):
            self.media_js = list(self.media_js)

        if isinstance(self.media_css, tuple):
            self.media_css = list(self.media_css)

        self.plugin = plugin

[docs]    def render(self, request=None):
        return ''

    @classproperty
[docs]    def html_class(cls):
        """
        HTML class of the ``dash.base.BaseDashboardPluginWidget``.

        :return str:
        """
        return ' '.join(cls.html_classes)


class BaseRegistry(object):
    """
    Registry of dash plugins. It's essential, that class registered has the ``uid`` property.
    """
    type = None

    def __init__(self):
        assert self.type
        self._registry = {}
        self._forced = []

    def register(self, cls, force=False):
        """
        Registers the plugin in the registry.

        :param mixed.
        """
        if not issubclass(cls, self.type):
            raise InvalidRegistryItemType("Invalid item type `{0}` for registry `{1}`".format(cls, self.__class__))

        # If item has not been forced yet, add/replace its' value in the registry
        if force:

            if not cls.uid in self._forced:
                self._registry[cls.uid] = cls
                self._forced.append(cls.uid)
                return True
            else:
                return False

        else:

            if cls.uid in self._registry:
                return False
            else:
                self._registry[cls.uid] = cls
                return True

    def unregister(self, cls):
        if not issubclass(cls, self.type):
            raise InvalidRegistryItemType("Invalid item type `{0}` for registry `{1}`".format(cls, self.__class__))

        # Only non-forced items are allowed to be unregistered.
        if cls.uid in self._registry and not cls.uid in self._forced:
            self._registry.pop(cls.uid)
            return True
        else:
            return False

    def get(self, uid, default=None):
        """
        Gets the given entry from the registry.

        :param str uid:
        :return mixed.
        """
        item = self._registry.get(uid, default)
        if not item:
            logger.debug("Can't find plugin with uid `{0}` in `{1}` registry".format(uid, self.__class__))
        return item


class PluginRegistry(BaseRegistry):
    """
    Plugin registry.
    """
    type = BaseDashboardPlugin


class LayoutRegistry(BaseRegistry):
    """
    Layout registry.
    """
    type = BaseDashboardLayout


class PluginWidgetRegistry(object):
    """
    Registry of dash plugins widgets (renderers).
    """
    type = BaseDashboardPluginWidget

    def __init__(self):
        assert self.type
        self._registry = {}
        self._forced = []

    @staticmethod
    def namify(layout, placeholder, plugin_uid):
        return '{0}.{1}.{2}'.format(layout, placeholder, plugin_uid)

    def register(self, cls, force=False):
        """
        Registers the plugin renderer in the registry.

        :param dash.base.BasePluginRenderer cls: Subclass of `dash.base.BasePluginRenderer`.
        """
        if not issubclass(cls, self.type):
            raise InvalidRegistryItemType("Invalid item type `{0}` for registry `{1}`".format(cls, self.__class__))

        uid = PluginWidgetRegistry.namify(cls.layout_uid, cls.placeholder_uid, cls.plugin_uid)

        # If item has not been forced yet, add/replace its' value in the registry
        if force:

            if not uid in self._forced:
                self._registry[uid] = cls
                self._forced.append(uid)
                return True
            else:
                return False

        else:

            if uid in self._registry:
                return False
            else:
                self._registry[uid] = cls
                return True

    def unregister(self, cls):
        if not issubclass(cls, self.type):
            raise InvalidRegistryItemType("Invalid item type `{0}` for registry `{1}`".format(cls, self.__class__))

        uid = PluginWidgetRegistry.namify(cls.layout_uid, cls.placeholder_uid, cls.plugin_uid)

        # Only non-forced items are allowed to be unregistered.
        if uid in self._registry and not uid in self._forced:
            self._registry.pop(uid)
            return True
        else:
            return False

    def get(self, uid, default=None):
        """
        Gets the given entry from the registry.

        :param str uid:
        :return mixed.
        """
        item = self._registry.get(uid, default)
        if not item:
            logger.debug("Can't find plugin with uid `{0}` in `{1}` registry".format(uid, self.__class__))
        return item


# Register plugins by calling plugin_registry.register()
plugin_registry = PluginRegistry()

# Register layouts by calling layout_registry.register()
layout_registry = LayoutRegistry()

# Register of plugin widgets.
plugin_widget_registry = PluginWidgetRegistry()

[docs]def ensure_autodiscover():
    """
    Ensures that plugins are autodiscovered.
    """
    if not (plugin_registry._registry and layout_registry._registry and plugin_widget_registry._registry):
        autodiscover()

[docs]def get_registered_plugins():
    """
    Gets a list of registered plugins in a form if tuple (plugin name, plugin description). If not yet
    autodiscovered, autodiscovers them.

    :return list:
    """
    ensure_autodiscover()

    registered_plugins = []

    for uid, plugin in plugin_registry._registry.items():
        registered_plugins.append((uid, force_text(plugin.name)))

    return registered_plugins

[docs]def get_registered_plugin_uids():
    """
    Gets a list of registered plugin uids as a list . If not yet autodiscovered, autodiscovers them.

    :return list:
    """
    ensure_autodiscover()

    registered_plugins = []

    for uid, plugin in plugin_registry._registry.items():
        registered_plugins.append(uid)
    return registered_plugins

[docs]def validate_placeholder_uid(layout, placeholder_uid):
    """
    Validates the placeholder.

    :param str layout_uid:
    :param str placeholder_uid:
    :return bool:
    """
    return placeholder_uid in layout.placeholder_uids

[docs]def validate_plugin_uid(plugin_uid):
    """
    Validates the plugin uid.

    :param str plugin_uid:
    :return bool:
    """
    return plugin_uid in get_registered_plugin_uids()

[docs]def get_registered_layouts():
    """
    Gets registered layouts.
    """
    ensure_autodiscover()

    registered_layouts = []

    for uid, layout in layout_registry._registry.items():
        registered_layouts.append((uid, force_text(layout.name)))

    return registered_layouts

[docs]def get_registered_layout_uids():
    """
    Gets uids of registered layouts.
    """
    return layout_registry._registry.keys()

[docs]def get_layout(layout_uid=None, as_instance=False):
    """
    Gets the layout by ``layout_uid`` given. If left empty, takes the default one chosen in settings.

    Raises a ``dash.exceptions.NoActiveLayoutChosen`` when no default layout could be found.

    :return dash.base.BaseDashboardLayout: Sublcass of `dash.base.BaseDashboardLayout`.
    """
    ensure_autodiscover()

    if not layout_uid:
        layout_uid = ACTIVE_LAYOUT

    layout_cls = layout_registry.get(layout_uid, None)
    if not layout_cls:
        raise LayoutDoesNotExist(_("Layout `{0}` does not exist!").format(layout_uid))

    if as_instance:
        return layout_cls()

    return layout_cls

[docs]def collect_widget_media(dashboard_entries):
    """
    Collects the widget media for dashboard entries given.

    :param iterable dashboard_entries: Iterable of ``dash.models.DashboardEntry`` instances.
    :return dict: Returns a dict containing the 'js' and 'css' keys. Correspondent values of those keys are
        lists containing paths to the CSS and JS media files.
    """
    media_js = []
    media_css = []
    for dashboard_entry in dashboard_entries:
        widget_cls = plugin_widget_registry.get(
            PluginWidgetRegistry.namify(
                dashboard_entry.layout_uid, dashboard_entry.placeholder_uid, dashboard_entry.plugin_uid
                )
        )
        if widget_cls:
            media_js += widget_cls.media_js
            media_css += widget_cls.media_css
        else:
            logger.debug("widget_cls empty for dashboard entry {0}".format(dashboard_entry.__dict__))
    return {'js': media_js, 'css': media_css}