Add custom form fields

anchor/forms/__init__.py

@@ -0,0 +1 @@
+from . import fields, widgets  # noqa

anchor/forms/fields.py

@@ -0,0 +1,7 @@
+from django import forms
+
+from .widgets import ClearableBlobInput
+
+
+class BlobField(forms.FileField):
+    widget = ClearableBlobInput

anchor/forms/widgets.py

@@ -0,0 +1,10 @@
+from django.forms.widgets import ClearableFileInput
+
+
+class ClearableBlobInput(ClearableFileInput):
+    # make this widget work with the Django admin
+    choices = []
+
+
+class AdminBlobInput(ClearableBlobInput):
+    template_name = "anchor/widgets/admin_blob_input.html"

anchor/models/fields/single_attachment.py

@@ -5,6 +5,7 @@
 from django.db import models
 from django.db.models import Model
 from django.db.models.fields.related_descriptors import ReverseOneToOneDescriptor
+from django.utils.text import capfirst
 
 from anchor.models import Attachment, Blob
 
@@ -151,17 +152,17 @@ def contribute_to_class(self, cls: type[Model], name: str, **kwargs) -> None:
         )
 
     def formfield(self, **kwargs):
-        from django.forms import ClearableFileInput, FileField
+        from anchor.forms.fields import BlobField
 
+        super().formfield(**kwargs)
         defaults = {
             "required": not self.blank,
-            "widget": ClearableFileInput,
-            "label": self.verbose_name.title() if self.verbose_name else None,
+            "label": capfirst(self.verbose_name),
             "help_text": self.help_text,
         }
         defaults.update(kwargs)
 
-        return FileField(**defaults)
+        return BlobField(**defaults)
 
     def get_forward_related_filter(self, obj):
         return {

anchor/templates/anchor/widgets/admin_blob_input.html

@@ -0,0 +1,25 @@
+{% load anchor %}
+<div style="display: flex; flex-wrap: wrap; gap: 0.5rem">
+    <div>
+        {% if widget.is_initial %}
+        {% if widget.value.is_image %}
+        <img style="max-width: 200px; max-height: 200px; object-fit: contain;"
+            src="{% variant_url widget.value resize_to_fit='200x200' %}">
+        {% else %}
+        {{ widget.initial_text }}: <a href="{{ widget.value.url }}">{{ widget.value }}</a>
+        {% endif %}
+        {% endif %}
+    </div>
+    <div>
+        {% if not widget.required and widget.is_initial %}
+        <div>
+            <div style="display: flex; align-items: center; gap: 0.25em">
+                <input type="checkbox" {% if widget.attrs.disabled %} disabled{% endif %}
+                    name="{{ widget.checkbox_name }}" id="{{ widget.checkbox_id }}">
+                <label for="{{ widget.checkbox_id }}">{{ widget.clear_checkbox_label }}</label>
+            </div>
+        </div>
+        {% endif %}
+        <input type="{{ widget.type }}" name="{{ widget.name }}" {% include "django/forms/widgets/attrs.html" %}>
+    </div>
+</div>

demo/movies/admin.py

@@ -1,9 +1,18 @@
 from django.contrib import admin
 
+from anchor.forms.widgets import AdminBlobInput
+from anchor.models.fields import SingleAttachmentField
+
 from .models import Movie
 
 
 @admin.register(Movie)
 class MovieAdmin(admin.ModelAdmin):
     list_display = ["title"]
     search_fields = ["title"]
+
+    formfield_overrides = {
+        SingleAttachmentField: {
+            "widget": AdminBlobInput,
+        },
+    }