baseviews.py

from datetime import date, datetime
from inspect import isclass
import json
import logging
import re

from flask import abort, Blueprint, flash, render_template, request, session, url_for

from ._compat import as_unicode
from .actions import ActionItem
from .const import PERMISSION_PREFIX
from .forms import GeneralModelConverter
from .urltools import (
    get_filter_args,
    get_order_args,
    get_page_args,
    get_page_size_args,
    Stack
)
from .widgets import FormWidget, ListWidget, SearchWidget, ShowWidget

log = logging.getLogger(__name__)


def expose(url="/", methods=("GET",)):
    """
        Use this decorator to expose views on your view classes.

        :param url:
            Relative URL for the view
        :param methods:
            Allowed HTTP methods. By default only GET is allowed.
    """

    def wrap(f):
        if not hasattr(f, "_urls"):
            f._urls = []
        f._urls.append((url, methods))
        return f

    return wrap


def expose_api(name="", url="", methods=("GET",), description=""):
    def wrap(f):
        api_name = name or f.__name__
        api_url = url or "/api/{0}".format(name)
        if not hasattr(f, "_urls"):
            f._urls = []
            f._extra = {}
        f._urls.append((api_url, methods))
        f._extra[api_name] = (api_url, f.__name__, description)
        return f

    return wrap


class BaseView(object):
    """
        All views inherit from this class.
        it's constructor will register your exposed urls on flask as a Blueprint.

        This class does not expose any urls, but provides a common base for all views.

        Extend this class if you want to expose methods for your own templates
    """

    appbuilder = None
    blueprint = None
    endpoint = None

    route_base = None
    """ Override this if you want to define your own relative url """

    template_folder = "templates"
    """ The template folder relative location """
    static_folder = "static"
    """  The static folder relative location """
    base_permissions = None
    """
        List with allowed base permission.
        Use it like this if you want to restrict your view to readonly::

            class MyView(ModelView):
                base_permissions = ['can_list','can_show']
    """
    class_permission_name = None
    """
        Override class permission name default fallback to self.__class__.__name__
    """
    previous_class_permission_name = None
    """
        If set security cleanup will remove all permissions tuples
        with this name
    """
    method_permission_name = None
    """
        Override method permission names, example::

            method_permissions_name = {
                'get_list': 'read',
                'get': 'read',
                'put': 'write',
                'post': 'write',
                'delete': 'write'
            }
    """
    previous_method_permission_name = None
    """
        Use same structure as method_permission_name. If set security converge
        will replace all method permissions by the new ones
    """
    default_view = "list"
    """ the default view for this BaseView, to be used with url_for (method name) """
    extra_args = None

    """ dictionary for injecting extra arguments into template """
    _apis = None

    def __init__(self):
        """
            Initialization of base permissions
            based on exposed methods and actions

            Initialization of extra args
        """
        # Init class permission override attrs
        if not self.previous_class_permission_name and self.class_permission_name:
            self.previous_class_permission_name = self.__class__.__name__
        self.class_permission_name = (self.class_permission_name or
                                      self.__class__.__name__)

        # Init previous permission override attrs
        is_collect_previous = False
        if not self.previous_method_permission_name and self.method_permission_name:
            self.previous_method_permission_name = dict()
            is_collect_previous = True
        self.method_permission_name = self.method_permission_name or dict()

        # Collect base_permissions and infer previous permissions
        is_add_base_permissions = False
        if self.base_permissions is None:
            self.base_permissions = set()
            is_add_base_permissions = True
        for attr_name in dir(self):
            if hasattr(getattr(self, attr_name), "_permission_name"):
                if is_collect_previous:
                    self.previous_method_permission_name[attr_name] = getattr(
                        getattr(self, attr_name), "_permission_name"
                    )
                _permission_name = self.get_method_permission(attr_name)
                if is_add_base_permissions:
                    self.base_permissions.add(PERMISSION_PREFIX + _permission_name)
        self.base_permissions = list(self.base_permissions)

        if not self.extra_args:
            self.extra_args = dict()
        self._apis = dict()
        for attr_name in dir(self):
            if hasattr(getattr(self, attr_name), "_extra"):
                _extra = getattr(getattr(self, attr_name), "_extra")
                for key in _extra:
                    self._apis[key] = _extra[key]

    def create_blueprint(self, appbuilder, endpoint=None, static_folder=None):
        """
            Create Flask blueprint. You will generally not use it

            :param appbuilder:
               the AppBuilder object
            :param endpoint:
               endpoint override for this blueprint,
               will assume class name if not provided
            :param static_folder:
               the relative override for static folder,
               if omitted application will use the appbuilder static
        """
        # Store appbuilder instance
        self.appbuilder = appbuilder

        # If endpoint name is not provided, get it from the class name
        self.endpoint = endpoint or self.__class__.__name__

        if self.route_base is None:
            self.route_base = "/" + self.__class__.__name__.lower()

        self.static_folder = static_folder
        if not static_folder:
            # Create blueprint and register rules
            self.blueprint = Blueprint(
                self.endpoint,
                __name__,
                url_prefix=self.route_base,
                template_folder=self.template_folder,
            )
        else:
            self.blueprint = Blueprint(
                self.endpoint,
                __name__,
                url_prefix=self.route_base,
                template_folder=self.template_folder,
                static_folder=static_folder,
            )
        self._register_urls()
        return self.blueprint

    def _register_urls(self):
        for attr_name in dir(self):
            attr = getattr(self, attr_name)
            if hasattr(attr, "_urls"):
                for url, methods in attr._urls:
                    log.info(
                        f"Registering route {self.blueprint.url_prefix}{url} {methods}"
                    )
                    self.blueprint.add_url_rule(url, attr_name, attr, methods=methods)

    def render_template(self, template, **kwargs):
        """
            Use this method on your own endpoints, will pass the extra_args
            to the templates.

            :param template: The template relative path
            :param kwargs: arguments to be passed to the template
        """
        kwargs["base_template"] = self.appbuilder.base_template
        kwargs["appbuilder"] = self.appbuilder
        return render_template(
            template, **dict(list(kwargs.items()) + list(self.extra_args.items()))
        )

    def _prettify_name(self, name):
        """
            Prettify pythonic variable name.

            For example, 'HelloWorld' will be converted to 'Hello World'

            :param name:
                Name to prettify.
        """
        return re.sub(r"(?<=.)([A-Z])", r" \1", name)

    def _prettify_column(self, name):
        """
            Prettify pythonic variable name.

            For example, 'hello_world' will be converted to 'Hello World'

            :param name:
                Name to prettify.
        """
        return re.sub("[._]", " ", name).title()

    def update_redirect(self):
        """
            Call it on your own endpoint's to update the back history navigation.
            If you bypass it, the next submit or back will go over it.
        """
        page_history = Stack(session.get("page_history", []))
        page_history.push(request.url)
        session["page_history"] = page_history.to_json()

    def get_redirect(self):
        """
            Returns the previous url.
        """
        index_url = self.appbuilder.get_url_for_index
        page_history = Stack(session.get("page_history", []))

        if page_history.pop() is None:
            return index_url
        session["page_history"] = page_history.to_json()
        url = page_history.pop() or index_url
        return url

    @classmethod
    def get_default_url(cls, **kwargs):
        """
            Returns the url for this class default endpoint
        """
        return url_for(cls.__name__ + "." + cls.default_view, **kwargs)

    def get_uninit_inner_views(self):
        """
            Will return a list with views that need to be initialized.
            Normally related_views from ModelView
        """
        return []

    def get_init_inner_views(self, views):
        """
            Sets initialized inner views
        """
        pass

    def get_method_permission(self, method_name: str) -> str:
        """
            Returns the permission name for a method
        """
        permission = self.method_permission_name.get(method_name)
        if permission:
            return permission
        else:
            return getattr(
                getattr(self, method_name), "_permission_name")


class BaseFormView(BaseView):
    """
        Base class FormView's
    """

    form_template = "appbuilder/general/model/edit.html"

    edit_widget = FormWidget
    """ Form widget to override """
    form_title = ""
    """ The form title to be displayed """
    form_columns = None
    """ The form columns to include, if empty will include all"""
    form = None
    """ The WTF form to render """
    form_fieldsets = None
    """ Form field sets """
    default_view = "this_form_get"
    """ The form view default entry endpoint """

    def _init_vars(self):
        self.form_columns = self.form_columns or []
        self.form_fieldsets = self.form_fieldsets or []
        list_cols = [field.name for field in self.form.refresh()]
        if self.form_fieldsets:
            self.form_columns = []
            for fieldset_item in self.form_fieldsets:
                self.form_columns = self.form_columns + list(
                    fieldset_item[1].get("fields")
                )
        else:
            if not self.form_columns:
                self.form_columns = list_cols

    def form_get(self, form):
        """
            Override this method to implement your form processing
        """
        pass

    def form_post(self, form):
        """
            Override this method to implement your form processing

            :param form: WTForm form

            Return None or a flask response to render
            a custom template or redirect the user
        """
        pass

    def _get_edit_widget(self, form=None, exclude_cols=None, widgets=None):
        exclude_cols = exclude_cols or []
        widgets = widgets or {}
        widgets["edit"] = self.edit_widget(
            route_base=self.route_base,
            form=form,
            include_cols=self.form_columns,
            exclude_cols=exclude_cols,
            fieldsets=self.form_fieldsets,
        )
        return widgets


class BaseModelView(BaseView):
    """
        The base class of ModelView and ChartView, all properties are inherited
        Customize ModelView and ChartView overriding this properties

        This class supports all the basics for query
    """

    datamodel = None
    """
        Your sqla model you must initialize it like::

            class MyView(ModelView):
                datamodel = SQLAInterface(MyTable)
    """

    title = "Title"

    search_columns = None
    """
        List with allowed search columns, if not provided
        all possible search columns will be used
        If you want to limit the search (*filter*) columns possibilities,
        define it with a list of column names from your model::

            class MyView(ModelView):
                datamodel = SQLAInterface(MyTable)
                search_columns = ['name','address']

    """
    search_exclude_columns = None
    """
        List with columns to exclude from search.
        Search includes all possible columns by default
    """
    search_form_extra_fields = None
    """
        A dictionary containing column names and a WTForm
        Form fields to be added to the Add form, these fields do not
        exist on the model itself ex::

        search_form_extra_fields = {'some_col':BooleanField('Some Col', default=False)}

    """
    search_form_query_rel_fields = None
    """
        Add Customized query for related fields on search form.
        Assign a dictionary where the keys are the column names of
        the related models to filter, the value for each key, is a list of lists with the
        same format as base_filter
        {'relation col name':[['Related model col',FilterClass,'Filter Value'],...],...}
        Add a custom filter to form related fields::

            class ContactModelView(ModelView):
                datamodel = SQLAModel(Contact, db.session)
                search_form_query_rel_fields = [('group':[['name',FilterStartsWith,'W']]}

    """

    label_columns = None
    """
        Dictionary of labels for your columns,
        override this if you want different pretify labels

        example (will just override the label for name column)::

            class MyView(ModelView):
                datamodel = SQLAInterface(MyTable)
                label_columns = {'name':'My Name Label Override'}

    """
    search_form = None
    """ To implement your own add WTF form for Search """
    base_filters = None
    """
        Filter the view use: [['column_name',BaseFilter,'value'],]

        example::

            def get_user():
                return g.user

            class MyView(ModelView):
                datamodel = SQLAInterface(MyTable)
                base_filters = [['created_by', FilterEqualFunction, get_user],
                                ['name', FilterStartsWith, 'a']]

    """

    base_order = None
    """
        Use this property to set default ordering for lists ('col_name','asc|desc')::

            class MyView(ModelView):
                datamodel = SQLAInterface(MyTable)
                base_order = ('my_column_name','asc')

    """

    search_widget = SearchWidget
    """ Search widget you can override with your own """

    _base_filters = None
    """ Internal base Filter from class Filters will always filter view """
    _filters = None
    """ Filters object will calculate all possible filter types
    based on search_columns """

    def __init__(self, **kwargs):
        """
            Constructor
        """
        datamodel = kwargs.get("datamodel", None)
        if datamodel:
            self.datamodel = datamodel
        self._init_properties()
        self._init_forms()
        self._init_titles()
        super(BaseModelView, self).__init__(**kwargs)

    def _gen_labels_columns(self, list_columns):
        """
            Auto generates pretty label_columns from list of columns
        """
        for col in list_columns:
            if not self.label_columns.get(col):
                self.label_columns[col] = self._prettify_column(col)

    def _init_titles(self):
        pass

    def _init_properties(self):
        self.label_columns = self.label_columns or {}
        self.base_filters = self.base_filters or []
        self.search_exclude_columns = self.search_exclude_columns or []
        self.search_columns = self.search_columns or []

        self._base_filters = self.datamodel.get_filters().add_filter_list(
            self.base_filters
        )
        list_cols = self.datamodel.get_columns_list()
        search_columns = self.datamodel.get_search_columns_list()
        if not self.search_columns:
            self.search_columns = [
                x for x in search_columns if x not in self.search_exclude_columns
            ]

        self._gen_labels_columns(list_cols)
        self._filters = self.datamodel.get_filters(self.search_columns)

    def _init_forms(self):
        conv = GeneralModelConverter(self.datamodel)
        if not self.search_form:
            self.search_form = conv.create_form(
                self.label_columns,
                self.search_columns,
                extra_fields=self.search_form_extra_fields,
                filter_rel_fields=self.search_form_query_rel_fields,
            )

    def _get_search_widget(self, form=None, exclude_cols=None, widgets=None):
        exclude_cols = exclude_cols or []
        widgets = widgets or {}
        widgets["search"] = self.search_widget(
            route_base=self.route_base,
            form=form,
            include_cols=self.search_columns,
            exclude_cols=exclude_cols,
            filters=self._filters,
        )
        return widgets

    def _label_columns_json(self):
        """
            Prepares dict with labels to be JSON serializable
        """
        ret = {}
        for key, value in list(self.label_columns.items()):
            ret[key] = as_unicode(value.encode("UTF-8"))
        return ret


class BaseCRUDView(BaseModelView):
    """
        The base class for ModelView, all properties are inherited
        Customize ModelView overriding this properties
    """

    related_views = None
    """
        List with ModelView classes
        Will be displayed related with this one using relationship sqlalchemy property::

            class MyView(ModelView):
                datamodel = SQLAModel(Group, db.session)
                related_views = [MyOtherRelatedView]

    """
    _related_views = None
    """ internal list with ref to instantiated view classes """
    list_title = ""
    """ List Title, if not configured the default is 'List ' with pretty model name """
    show_title = ""
    """ Show Title , if not configured the default is 'Show ' with pretty model name """
    add_title = ""
    """ Add Title , if not configured the default is 'Add ' with pretty model name """
    edit_title = ""
    """ Edit Title , if not configured the default is 'Edit ' with pretty model name """

    list_columns = None
    """
        A list of columns (or model's methods) to be displayed on the list view.
        Use it to control the order of the display
    """
    show_columns = None
    """
        A list of columns (or model's methods) to be displayed on the show view.
        Use it to control the order of the display
    """
    add_columns = None
    """
        A list of columns (or model's methods) to be displayed on the add form view.
        Use it to control the order of the display
    """
    edit_columns = None
    """
        A list of columns (or model's methods) to be displayed on the edit form view.
        Use it to control the order of the display
    """
    show_exclude_columns = None
    """
       A list of columns to exclude from the show view.
       By default all columns are included.
    """
    add_exclude_columns = None
    """
       A list of columns to exclude from the add form.
       By default all columns are included.
    """
    edit_exclude_columns = None
    """
       A list of columns to exclude from the edit form.
        By default all columns are included.
    """
    order_columns = None
    """ Allowed order columns """
    page_size = 10
    """
        Use this property to change default page size
    """
    show_fieldsets = None
    """
        show fieldsets django style [(<'TITLE'|None>, {'fields':[<F1>,<F2>,...]}),....]

        ::

            class MyView(ModelView):
                datamodel = SQLAModel(MyTable, db.session)

                show_fieldsets = [
                    ('Summary', {
                        'fields': [
                            'name',
                            'address',
                            'group'
                            ]
                        }
                    ),
                    ('Personal Info', {
                        'fields': [
                            'birthday',
                            'personal_phone'
                            ],
                        'expanded':False
                        }
                    ),
                ]

    """
    add_fieldsets = None
    """
        add fieldsets django style (look at show_fieldsets for an example)
    """
    edit_fieldsets = None
    """
        edit fieldsets django style (look at show_fieldsets for an example)
    """

    description_columns = None
    """
        Dictionary with column descriptions that will be shown on the forms::

            class MyView(ModelView):
                datamodel = SQLAModel(MyTable, db.session)

                description_columns = {
                    'name': 'your models name column',
                    'address': 'the address column'
                }
    """
    validators_columns = None
    """ Dictionary to add your own validators for forms """
    formatters_columns = None
    """ Dictionary of formatter used to format the display of columns

        formatters_columns = {'some_date_col': lambda x: x.isoformat() }
    """
    add_form_extra_fields = None
    """
        A dictionary containing column names and a WTForm
        Form fields to be added to the Add form, these fields do not
        exist on the model itself ex::

        add_form_extra_fields = {'some_col':BooleanField('Some Col', default=False)}

    """
    edit_form_extra_fields = None
    """ Dictionary to add extra fields to the Edit form using this property """

    add_form_query_rel_fields = None
    """
        Add Customized query for related fields to add form.
        Assign a dictionary where the keys are the column names of
        the related models to filter, the value for each key, is a list of lists with the
        same format as base_filter
        {
            'relation col name':
                [['Related model col', FilterClass, 'Filter Value'],...],...
        }
        Add a custom filter to form related fields::

            class ContactModelView(ModelView):
                datamodel = SQLAModel(Contact, db.session)
                add_form_query_rel_fields = {'group': [['name', FilterStartsWith, 'W']]}

    """
    edit_form_query_rel_fields = None
    """
        Add Customized query for related fields to edit form.
        Assign a dictionary where the keys are the column names of
        the related models to filter, the value for each key, is a list of lists with the
        same format as base_filter
        {
            'relation col name':
                [['Related model col', FilterClass, 'Filter Value'],...],...
        }
        Add a custom filter to form related fields::

            class ContactModelView(ModelView):
                datamodel = SQLAModel(Contact, db.session)
                edit_form_query_rel_fields = {'group':[['name',FilterStartsWith,'W']]}

    """

    add_form = None
    """ To implement your own, assign WTF form for Add """
    edit_form = None
    """ To implement your own, assign WTF form for Edit """

    list_template = "appbuilder/general/model/list.html"
    """ Your own add jinja2 template for list """
    edit_template = "appbuilder/general/model/edit.html"
    """ Your own add jinja2 template for edit """
    add_template = "appbuilder/general/model/add.html"
    """ Your own add jinja2 template for add """
    show_template = "appbuilder/general/model/show.html"
    """ Your own add jinja2 template for show """

    list_widget = ListWidget
    """ List widget override """
    edit_widget = FormWidget
    """ Edit widget override """
    add_widget = FormWidget
    """ Add widget override """
    show_widget = ShowWidget
    """ Show widget override """

    actions = None

    def __init__(self, **kwargs):
        super(BaseCRUDView, self).__init__(**kwargs)
        # collect and setup actions
        self.actions = {}
        for attr_name in dir(self):
            func = getattr(self, attr_name)
            if hasattr(func, "_action"):
                action = ActionItem(*func._action, func=func)
                permission_name = action.name
                # Infer previous if not declared
                if self.method_permission_name.get(attr_name):
                    if not self.previous_method_permission_name.get(attr_name):
                        self.previous_method_permission_name[attr_name] = action.name
                    permission_name = \
                        PERMISSION_PREFIX + self.method_permission_name.get(attr_name)
                if permission_name not in self.base_permissions:
                    self.base_permissions.append(permission_name)
                self.actions[action.name] = action

    def _init_forms(self):
        """
            Init forms for Add and Edit
        """
        super(BaseCRUDView, self)._init_forms()
        conv = GeneralModelConverter(self.datamodel)
        if not self.add_form:
            self.add_form = conv.create_form(
                self.label_columns,
                self.add_columns,
                self.description_columns,
                self.validators_columns,
                self.add_form_extra_fields,
                self.add_form_query_rel_fields,
            )
        if not self.edit_form:
            self.edit_form = conv.create_form(
                self.label_columns,
                self.edit_columns,
                self.description_columns,
                self.validators_columns,
                self.edit_form_extra_fields,
                self.edit_form_query_rel_fields,
            )

    def _init_titles(self):
        """
            Init Titles if not defined
        """
        super(BaseCRUDView, self)._init_titles()
        class_name = self.datamodel.model_name
        if not self.list_title:
            self.list_title = "List " + self._prettify_name(class_name)
        if not self.add_title:
            self.add_title = "Add " + self._prettify_name(class_name)
        if not self.edit_title:
            self.edit_title = "Edit " + self._prettify_name(class_name)
        if not self.show_title:
            self.show_title = "Show " + self._prettify_name(class_name)
        self.title = self.list_title

    def _init_properties(self):
        """
            Init Properties
        """
        super(BaseCRUDView, self)._init_properties()
        # Reset init props
        self.related_views = self.related_views or []
        self._related_views = self._related_views or []
        self.description_columns = self.description_columns or {}
        self.validators_columns = self.validators_columns or {}
        self.formatters_columns = self.formatters_columns or {}
        self.add_form_extra_fields = self.add_form_extra_fields or {}
        self.edit_form_extra_fields = self.edit_form_extra_fields or {}
        self.show_exclude_columns = self.show_exclude_columns or []
        self.add_exclude_columns = self.add_exclude_columns or []
        self.edit_exclude_columns = self.edit_exclude_columns or []
        # Generate base props
        list_cols = self.datamodel.get_user_columns_list()
        self.list_columns = self.list_columns or [list_cols[0]]
        self._gen_labels_columns(self.list_columns)
        self.order_columns = (
            self.order_columns or
            self.datamodel.get_order_columns_list(list_columns=self.list_columns)
        )
        if self.show_fieldsets:
            self.show_columns = []
            for fieldset_item in self.show_fieldsets:
                self.show_columns = self.show_columns + list(
                    fieldset_item[1].get("fields")
                )
        else:
            if not self.show_columns:
                self.show_columns = [
                    x for x in list_cols if x not in self.show_exclude_columns
                ]
        if self.add_fieldsets:
            self.add_columns = []
            for fieldset_item in self.add_fieldsets:
                self.add_columns = self.add_columns + list(
                    fieldset_item[1].get("fields")
                )
        else:
            if not self.add_columns:
                self.add_columns = [
                    x for x in list_cols if x not in self.add_exclude_columns
                ]
        if self.edit_fieldsets:
            self.edit_columns = []
            for fieldset_item in self.edit_fieldsets:
                self.edit_columns = self.edit_columns + list(
                    fieldset_item[1].get("fields")
                )
        else:
            if not self.edit_columns:
                self.edit_columns = [
                    x for x in list_cols if x not in self.edit_exclude_columns
                ]

    """
    -----------------------------------------------------
            GET WIDGETS SECTION
    -----------------------------------------------------
    """

    def _get_related_view_widget(
            self,
            item,
            related_view,
            order_column="",
            order_direction="",
            page=None,
            page_size=None,
    ):

        fk = related_view.datamodel.get_related_fk(self.datamodel.obj)
        filters = related_view.datamodel.get_filters()
        # Check if it's a many to one model relation
        if related_view.datamodel.is_relation_many_to_one(fk):
            filters.add_filter_related_view(
                fk,
                self.datamodel.FilterRelationOneToManyEqual,
                self.datamodel.get_pk_value(item),
            )
        # Check if it's a many to many model relation
        elif related_view.datamodel.is_relation_many_to_many(fk):
            filters.add_filter_related_view(
                fk,
                self.datamodel.FilterRelationManyToManyEqual,
                self.datamodel.get_pk_value(item),
            )
        else:
            if isclass(related_view) and issubclass(related_view, BaseView):
                name = related_view.__name__
            else:
                name = related_view.__class__.__name__
            log.error("Can't find relation on related view {0}".format(name))
            return None
        return related_view._get_view_widget(
            filters=filters,
            order_column=order_column,
            order_direction=order_direction,
            page=page,
            page_size=page_size,
        )

    def _get_related_views_widgets(
            self, item, orders=None, pages=None, page_sizes=None, widgets=None, **args
    ):
        """
            :return:
                Returns a dict with 'related_views' key with a list of
                Model View widgets
        """
        widgets = widgets or {}
        widgets["related_views"] = []
        for view in self._related_views:
            if orders.get(view.__class__.__name__):
                order_column, order_direction = orders.get(view.__class__.__name__)
            else:
                order_column, order_direction = "", ""
            widgets["related_views"].append(
                self._get_related_view_widget(
                    item,
                    view,
                    order_column,
                    order_direction,
                    page=pages.get(view.__class__.__name__),
                    page_size=page_sizes.get(view.__class__.__name__),
                )
            )
        return widgets

    def _get_view_widget(self, **kwargs):
        """
            :return:
                Returns a Model View widget
        """
        return self._get_list_widget(**kwargs).get("list")

    def _get_list_widget(
            self,
            filters,
            actions=None,
            order_column="",
            order_direction="",
            page=None,
            page_size=None,
            widgets=None,
            **args
    ):

        """ get joined base filter and current active filter for query """
        widgets = widgets or {}
        actions = actions or self.actions
        page_size = page_size or self.page_size
        if not order_column and self.base_order:
            order_column, order_direction = self.base_order
        joined_filters = filters.get_joined_filters(self._base_filters)
        count, lst = self.datamodel.query(
            joined_filters,
            order_column,
            order_direction,
            page=page,
            page_size=page_size,
        )
        pks = self.datamodel.get_keys(lst)

        # serialize composite pks
        pks = [self._serialize_pk_if_composite(pk) for pk in pks]

        widgets["list"] = self.list_widget(
            label_columns=self.label_columns,
            include_columns=self.list_columns,
            value_columns=self.datamodel.get_values(lst, self.list_columns),
            order_columns=self.order_columns,
            formatters_columns=self.formatters_columns,
            page=page,
            page_size=page_size,
            count=count,
            pks=pks,
            actions=actions,
            filters=filters,
            modelview_name=self.__class__.__name__,
        )
        return widgets

    def _get_show_widget(
            self, pk, item, widgets=None, actions=None, show_fieldsets=None
    ):
        widgets = widgets or {}
        actions = actions or self.actions
        show_fieldsets = show_fieldsets or self.show_fieldsets
        widgets["show"] = self.show_widget(
            pk=pk,
            label_columns=self.label_columns,
            include_columns=self.show_columns,
            value_columns=self.datamodel.get_values_item(item, self.show_columns),
            formatters_columns=self.formatters_columns,
            actions=actions,
            fieldsets=show_fieldsets,
            modelview_name=self.__class__.__name__,
        )
        return widgets

    def _get_add_widget(self, form, exclude_cols=None, widgets=None):
        exclude_cols = exclude_cols or []
        widgets = widgets or {}
        widgets["add"] = self.add_widget(
            form=form,
            include_cols=self.add_columns,
            exclude_cols=exclude_cols,
            fieldsets=self.add_fieldsets,
        )
        return widgets

    def _get_edit_widget(self, form, exclude_cols=None, widgets=None):
        exclude_cols = exclude_cols or []
        widgets = widgets or {}
        widgets["edit"] = self.edit_widget(
            form=form,
            include_cols=self.edit_columns,
            exclude_cols=exclude_cols,
            fieldsets=self.edit_fieldsets,
        )
        return widgets

    def get_uninit_inner_views(self):
        """
            Will return a list with views that need to be initialized.
            Normally related_views from ModelView
        """
        return self.related_views

    def get_init_inner_views(self):
        """
            Get the list of related ModelViews after they have been initialized
        """
        return self._related_views

    """
    -----------------------------------------------------
            CRUD functions behaviour
    -----------------------------------------------------
    """

    def _list(self):
        """
            list function logic, override to implement different logic
            returns list and search widget
        """
        if get_order_args().get(self.__class__.__name__):
            order_column, order_direction = get_order_args().get(
                self.__class__.__name__
            )
        else:
            order_column, order_direction = "", ""
        page = get_page_args().get(self.__class__.__name__)
        page_size = get_page_size_args().get(self.__class__.__name__)
        get_filter_args(self._filters)
        widgets = self._get_list_widget(
            filters=self._filters,
            order_column=order_column,
            order_direction=order_direction,
            page=page,
            page_size=page_size,
        )
        form = self.search_form.refresh()
        self.update_redirect()
        return self._get_search_widget(form=form, widgets=widgets)

    def _show(self, pk):
        """
            show function logic, override to implement different logic
            returns show and related list widget
        """
        pages = get_page_args()
        page_sizes = get_page_size_args()
        orders = get_order_args()

        item = self.datamodel.get(pk, self._base_filters)
        if not item:
            abort(404)
        widgets = self._get_show_widget(pk, item)
        self.update_redirect()
        return self._get_related_views_widgets(
            item, orders=orders, pages=pages, page_sizes=page_sizes, widgets=widgets
        )

    def _add(self):
        """
            Add function logic, override to implement different logic
            returns add widget or None
        """
        is_valid_form = True
        get_filter_args(self._filters)
        exclude_cols = self._filters.get_relation_cols()
        form = self.add_form.refresh()

        if request.method == "POST":
            self._fill_form_exclude_cols(exclude_cols, form)
            if form.validate():
                self.process_form(form, True)
                item = self.datamodel.obj()

                try:
                    form.populate_obj(item)
                    self.pre_add(item)
                except Exception as e:
                    flash(str(e), "danger")
                else:
                    if self.datamodel.add(item):
                        self.post_add(item)
                    flash(*self.datamodel.message)
                finally:
                    return None
            else:
                is_valid_form = False
        if is_valid_form:
            self.update_redirect()
        return self._get_add_widget(form=form, exclude_cols=exclude_cols)

    def _edit(self, pk):
        """
            Edit function logic, override to implement different logic
            returns Edit widget and related list or None
        """
        is_valid_form = True
        pages = get_page_args()
        page_sizes = get_page_size_args()
        orders = get_order_args()
        get_filter_args(self._filters)
        exclude_cols = self._filters.get_relation_cols()

        item = self.datamodel.get(pk, self._base_filters)
        if not item:
            abort(404)
        # convert pk to correct type, if pk is non string type.
        pk = self.datamodel.get_pk_value(item)

        if request.method == "POST":
            form = self.edit_form.refresh(request.form)
            # fill the form with the suppressed cols, generated from exclude_cols
            self._fill_form_exclude_cols(exclude_cols, form)
            # trick to pass unique validation
            form._id = pk
            if form.validate():
                self.process_form(form, False)

                try:
                    form.populate_obj(item)
                    self.pre_update(item)
                except Exception as e:
                    flash(str(e), "danger")
                else:
                    if self.datamodel.edit(item):
                        self.post_update(item)
                    flash(*self.datamodel.message)
                finally:
                    return None
            else:
                is_valid_form = False
        else:
            # Only force form refresh for select cascade events
            form = self.edit_form.refresh(obj=item)
            # Perform additional actions to pre-fill the edit form.
            self.prefill_form(form, pk)

        widgets = self._get_edit_widget(form=form, exclude_cols=exclude_cols)
        widgets = self._get_related_views_widgets(
            item,
            filters={},
            orders=orders,
            pages=pages,
            page_sizes=page_sizes,
            widgets=widgets,
        )
        if is_valid_form:
            self.update_redirect()
        return widgets

    def _delete(self, pk):
        """
            Delete function logic, override to implement different logic
            deletes the record with primary_key = pk

            :param pk:
                record primary key to delete
        """
        item = self.datamodel.get(pk, self._base_filters)
        if not item:
            abort(404)
        try:
            self.pre_delete(item)
        except Exception as e:
            flash(str(e), "danger")
        else:
            if self.datamodel.delete(item):
                self.post_delete(item)
            flash(*self.datamodel.message)
            self.update_redirect()

    """
    ------------------------------------------------
                HELPER FUNCTIONS
    ------------------------------------------------
    """

    def _serialize_pk_if_composite(self, pk):
        def date_serializer(obj):
            if isinstance(obj, datetime):
                return {"_type": "datetime", "value": obj.isoformat()}
            elif isinstance(obj, date):
                return {"_type": "date", "value": obj.isoformat()}

        if self.datamodel.is_pk_composite():
            try:
                pk = json.dumps(pk, default=date_serializer)
            except Exception:
                pass
        return pk

    def _deserialize_pk_if_composite(self, pk):
        def date_deserializer(obj):
            if "_type" not in obj:
                return obj

            from dateutil import parser

            if obj["_type"] == "datetime":
                return parser.parse(obj["value"])
            elif obj["_type"] == "date":
                return parser.parse(obj["value"]).date()
            return obj

        if self.datamodel.is_pk_composite():
            try:
                pk = json.loads(pk, object_hook=date_deserializer)
            except Exception:
                pass
        return pk

    def _fill_form_exclude_cols(self, exclude_cols, form):
        """
            fill the form with the suppressed cols, generated from exclude_cols
        """
        for filter_key in exclude_cols:
            filter_value = self._filters.get_filter_value(filter_key)
            rel_obj = self.datamodel.get_related_obj(filter_key, filter_value)
            if hasattr(form, filter_key):
                field = getattr(form, filter_key)
                field.data = rel_obj

    def prefill_form(self, form, pk):
        """
            Override this, will be called only if the current action is rendering
            an edit form (a GET request), and is used to perform additional action to
            prefill the form.

            This is useful when you have added custom fields that depend on the
            database contents. Fields that were added by name of a normal column
            or relationship should work out of the box.

            example::

                def prefill_form(self, form, pk):
                    if form.email.data:
                        form.email_confirmation.data = form.email.data
        """
        pass

    def process_form(self, form, is_created):
        """
            Override this, will be called only if the current action is submitting
            a create/edit form (a POST request), and is used to perform additional
            action before the form is used to populate the item.

            By default does nothing.

            example::

                def process_form(self, form, is_created):
                    if not form.owner:
                        form.owner.data = 'n/a'
        """
        pass

    def pre_update(self, item):
        """
            Override this, this method is called before the update takes place.
            If an exception is raised by this method,
            the message is shown to the user and the update operation is
            aborted. Because of this behavior, it can be used as a way to
            implement more complex logic around updates. For instance
            allowing only the original creator of the object to update it.
        """
        pass

    def post_update(self, item):
        """
            Override this, will be called after update
        """
        pass

    def pre_add(self, item):
        """
            Override this, will be called before add.
            If an exception is raised by this method,
            the message is shown to the user and the add operation is aborted.
        """
        pass

    def post_add(self, item):
        """
            Override this, will be called after update
        """
        pass

    def pre_delete(self, item):
        """
            Override this, will be called before delete
            If an exception is raised by this method,
            the message is shown to the user and the delete operation is
            aborted. Because of this behavior, it can be used as a way to
            implement more complex logic around deletes. For instance
            allowing only the original creator of the object to delete it.
        """
        pass

    def post_delete(self, item):
        """
            Override this, will be called after delete
        """
        pass