Closes #9416: Dashboard widgets (#11823)

* Replace masonry with gridstack

* Initial work on dashboard widgets

* Implement function to save dashboard layout

* Define a default dashboard

* Clean up widgets

* Implement widget configuration views & forms

* Permit merging dict value with existing dict in user config

* Add widget deletion view

* Enable HTMX for widget configuration

* Implement view to add dashboard widgets

* ObjectCountsWidget: Identify models by app_label & name

* Add color customization to dashboard widgets

* Introduce Dashboard model to store user dashboard layout & config

* Clean up utility functions

* Remove hard-coded API URL

* Use fixed grid cell height

* Add modal close button

* Clean up dashboard views

* Rebuild JS

netbox/extras/dashboard/widgets.py

@@ -0,0 +1,119 @@
+import uuid
+
+from django import forms
+from django.contrib.contenttypes.models import ContentType
+from django.template.loader import render_to_string
+from django.utils.translation import gettext as _
+
+from utilities.forms import BootstrapMixin
+from utilities.templatetags.builtins.filters import render_markdown
+from utilities.utils import content_type_identifier, content_type_name
+from .utils import register_widget
+
+__all__ = (
+    'ChangeLogWidget',
+    'DashboardWidget',
+    'NoteWidget',
+    'ObjectCountsWidget',
+)
+
+
+def get_content_type_labels():
+    return [
+        (content_type_identifier(ct), content_type_name(ct))
+        for ct in ContentType.objects.order_by('app_label', 'model')
+    ]
+
+
+class DashboardWidget:
+    default_title = None
+    description = None
+    width = 4
+    height = 3
+
+    class ConfigForm(forms.Form):
+        pass
+
+    def __init__(self, id=None, title=None, color=None, config=None, width=None, height=None, x=None, y=None):
+        self.id = id or str(uuid.uuid4())
+        self.config = config or {}
+        self.title = title or self.default_title
+        self.color = color
+        if width:
+            self.width = width
+        if height:
+            self.height = height
+        self.x, self.y = x, y
+
+    def __str__(self):
+        return self.title or self.__class__.__name__
+
+    def set_layout(self, grid_item):
+        self.width = grid_item['w']
+        self.height = grid_item['h']
+        self.x = grid_item.get('x')
+        self.y = grid_item.get('y')
+
+    def render(self, request):
+        raise NotImplementedError(f"{self.__class__} must define a render() method.")
+
+    @property
+    def name(self):
+        return f'{self.__class__.__module__.split(".")[0]}.{self.__class__.__name__}'
+
+    @property
+    def form_data(self):
+        return {
+            'title': self.title,
+            'color': self.color,
+            'config': self.config,
+        }
+
+
+@register_widget
+class NoteWidget(DashboardWidget):
+    description = _('Display some arbitrary custom content. Markdown is supported.')
+
+    class ConfigForm(BootstrapMixin, forms.Form):
+        content = forms.CharField(
+            widget=forms.Textarea()
+        )
+
+    def render(self, request):
+        return render_markdown(self.config.get('content'))
+
+
+@register_widget
+class ObjectCountsWidget(DashboardWidget):
+    default_title = _('Objects')
+    description = _('Display a set of NetBox models and the number of objects created for each type.')
+    template_name = 'extras/dashboard/widgets/objectcounts.html'
+
+    class ConfigForm(BootstrapMixin, forms.Form):
+        models = forms.MultipleChoiceField(
+            choices=get_content_type_labels
+        )
+
+    def render(self, request):
+        counts = []
+        for content_type_id in self.config['models']:
+            app_label, model_name = content_type_id.split('.')
+            model = ContentType.objects.get_by_natural_key(app_label, model_name).model_class()
+            object_count = model.objects.restrict(request.user, 'view').count
+            counts.append((model, object_count))
+
+        return render_to_string(self.template_name, {
+            'counts': counts,
+        })
+
+
+@register_widget
+class ChangeLogWidget(DashboardWidget):
+    default_title = _('Change Log')
+    description = _('Display the most recent records from the global change log.')
+    template_name = 'extras/dashboard/widgets/changelog.html'
+    width = 12
+    height = 4
+
+    def render(self, request):
+        return render_to_string(self.template_name, {})