Remove a migration operation failing on Django 6.0 (safe)

ram/bookshelf/admin.py

@@ -2,17 +2,13 @@ import html
 
 from django.conf import settings
 from django.contrib import admin
-from django.utils.html import format_html, strip_tags
+from django.utils.html import format_html, format_html_join, strip_tags
 from adminsortable2.admin import SortableAdminBase, SortableInlineAdminMixin
 
 from ram.admin import publish, unpublish
 from ram.utils import generate_csv
 from portal.utils import get_site_conf
-from repository.models import (
+from repository.models import BookDocument, CatalogDocument
-    BookDocument,
-    CatalogDocument,
-    MagazineIssueDocument
-)
 from bookshelf.models import (
     BaseBookProperty,
     BaseBookImage,
@@ -20,8 +16,6 @@ from bookshelf.models import (
     Author,
     Publisher,
     Catalog,
-    Magazine,
-    MagazineIssue,
 )
 
 
@@ -54,10 +48,6 @@ class CatalogDocInline(BookDocInline):
     model = CatalogDocument
 
 
-class MagazineIssueDocInline(BookDocInline):
-    model = MagazineIssueDocument
-
-
 @admin.register(Book)
 class BookAdmin(SortableAdminBase, admin.ModelAdmin):
     inlines = (
@@ -133,13 +123,14 @@ class BookAdmin(SortableAdminBase, admin.ModelAdmin):
     @admin.display(description="Invoices")
     def invoices(self, obj):
         if obj.invoice.exists():
-            html = "<br>".join(
+            html = format_html_join(
-                "<a href=\"{}\" target=\"_blank\">{}</a>".format(
+                "<br>",
-                    i.file.url, i
+                "<a href=\"{}\" target=\"_blank\">{}</a>",
-                ) for i in obj.invoice.all())
+                ((i.file.url, i) for i in obj.invoice.all())
+            )
         else:
             html = "-"
-        return format_html(html)
+        return html
 
     @admin.display(description="Publisher")
     def get_publisher(self, obj):
@@ -217,7 +208,7 @@ class PublisherAdmin(admin.ModelAdmin):
     @admin.display(description="Country")
     def country_flag(self, obj):
         return format_html(
-            '<img src="{}" /> {}'.format(obj.country.flag, obj.country.name)
+            '<img src="{}" /> {}', obj.country.flag, obj.country.name
         )
 
 
@@ -295,13 +286,14 @@ class CatalogAdmin(SortableAdminBase, admin.ModelAdmin):
     @admin.display(description="Invoices")
     def invoices(self, obj):
         if obj.invoice.exists():
-            html = "<br>".join(
+            html = format_html_join(
-                "<a href=\"{}\" target=\"_blank\">{}</a>".format(
+                "<br>",
-                    i.file.url, i
+                "<a href=\"{}\" target=\"_blank\">{}</a>",
-                ) for i in obj.invoice.all())
+                ((i.file.url, i) for i in obj.invoice.all())
+            )
         else:
             html = "-"
-        return format_html(html)
+        return html
 
     def download_csv(modeladmin, request, queryset):
         header = [
@@ -354,47 +346,3 @@ class CatalogAdmin(SortableAdminBase, admin.ModelAdmin):
 
     download_csv.short_description = "Download selected items as CSV"
     actions = [publish, unpublish, download_csv]
-
-
-@admin.register(Issue)
-class MagazineIssueAdmin(admin.ModelAdmin):
-    inlines = (
-        BookPropertyInline,
-        BookImageInline,
-        MagazineIssueDocInline,
-    )
-    list_display = (
-        "__str__",
-        "issue_number",
-        "published",
-    )
-    # autocomplete_fields = ("publisher",)
-    # readonly_fields = ("creation_time", "updated_time")
-    # search_fields = ("title", "publisher__name")
-    # list_filter = ("publisher__name", "language")
-
-    def get_model_perms(self, request):
-        """
-        Return empty perms dict thus hiding the model from admin index.
-        """
-        return {}
-
-    actions = [publish, unpublish]
-
-
-@admin.register(Magazine)
-class MagazineAdmin(admin.ModelAdmin):
-    inlines = (
-        MagazineIssueInline,
-    )
-    list_display = (
-        "__str__",
-        "publisher",
-        "published",
-    )
-    autocomplete_fields = ("publisher",)
-    readonly_fields = ("creation_time", "updated_time")
-    search_fields = ("name", "publisher__name")
-    list_filter = ("publisher__name", "language")
-
-    actions = [publish, unpublish]

ram/bookshelf/migrations/0016_basebook_book_catalogue.py

@@ -101,10 +101,10 @@ class Migration(migrations.Migration):
             model_name="basebook",
             name="old_title",
         ),
-        migrations.RemoveField(
+        # migrations.RemoveField(
-            model_name="basebook",
+        #     model_name="basebook",
-            name="old_authors",
+        #     name="old_authors",
-        ),
+        # ),
         migrations.RemoveField(
             model_name="basebook",
             name="old_publisher",

ram/bookshelf/migrations/0024_alter_basebook_language.py

@@ -0,0 +1,123 @@
+# Generated by Django 6.0 on 2025-12-03 22:07
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("bookshelf", "0023_delete_basebookdocument"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="basebook",
+            name="language",
+            field=models.CharField(
+                choices=[
+                    ("af", "Afrikaans"),
+                    ("ar", "Arabic"),
+                    ("ar-dz", "Algerian Arabic"),
+                    ("ast", "Asturian"),
+                    ("az", "Azerbaijani"),
+                    ("bg", "Bulgarian"),
+                    ("be", "Belarusian"),
+                    ("bn", "Bengali"),
+                    ("br", "Breton"),
+                    ("bs", "Bosnian"),
+                    ("ca", "Catalan"),
+                    ("ckb", "Central Kurdish (Sorani)"),
+                    ("cs", "Czech"),
+                    ("cy", "Welsh"),
+                    ("da", "Danish"),
+                    ("de", "German"),
+                    ("dsb", "Lower Sorbian"),
+                    ("el", "Greek"),
+                    ("en", "English"),
+                    ("en-au", "Australian English"),
+                    ("en-gb", "British English"),
+                    ("eo", "Esperanto"),
+                    ("es", "Spanish"),
+                    ("es-ar", "Argentinian Spanish"),
+                    ("es-co", "Colombian Spanish"),
+                    ("es-mx", "Mexican Spanish"),
+                    ("es-ni", "Nicaraguan Spanish"),
+                    ("es-ve", "Venezuelan Spanish"),
+                    ("et", "Estonian"),
+                    ("eu", "Basque"),
+                    ("fa", "Persian"),
+                    ("fi", "Finnish"),
+                    ("fr", "French"),
+                    ("fy", "Frisian"),
+                    ("ga", "Irish"),
+                    ("gd", "Scottish Gaelic"),
+                    ("gl", "Galician"),
+                    ("he", "Hebrew"),
+                    ("hi", "Hindi"),
+                    ("hr", "Croatian"),
+                    ("hsb", "Upper Sorbian"),
+                    ("ht", "Haitian Creole"),
+                    ("hu", "Hungarian"),
+                    ("hy", "Armenian"),
+                    ("ia", "Interlingua"),
+                    ("id", "Indonesian"),
+                    ("ig", "Igbo"),
+                    ("io", "Ido"),
+                    ("is", "Icelandic"),
+                    ("it", "Italian"),
+                    ("ja", "Japanese"),
+                    ("ka", "Georgian"),
+                    ("kab", "Kabyle"),
+                    ("kk", "Kazakh"),
+                    ("km", "Khmer"),
+                    ("kn", "Kannada"),
+                    ("ko", "Korean"),
+                    ("ky", "Kyrgyz"),
+                    ("lb", "Luxembourgish"),
+                    ("lt", "Lithuanian"),
+                    ("lv", "Latvian"),
+                    ("mk", "Macedonian"),
+                    ("ml", "Malayalam"),
+                    ("mn", "Mongolian"),
+                    ("mr", "Marathi"),
+                    ("ms", "Malay"),
+                    ("my", "Burmese"),
+                    ("nb", "Norwegian Bokmål"),
+                    ("ne", "Nepali"),
+                    ("nl", "Dutch"),
+                    ("nn", "Norwegian Nynorsk"),
+                    ("os", "Ossetic"),
+                    ("pa", "Punjabi"),
+                    ("pl", "Polish"),
+                    ("pt", "Portuguese"),
+                    ("pt-br", "Brazilian Portuguese"),
+                    ("ro", "Romanian"),
+                    ("ru", "Russian"),
+                    ("sk", "Slovak"),
+                    ("sl", "Slovenian"),
+                    ("sq", "Albanian"),
+                    ("sr", "Serbian"),
+                    ("sr-latn", "Serbian Latin"),
+                    ("sv", "Swedish"),
+                    ("sw", "Swahili"),
+                    ("ta", "Tamil"),
+                    ("te", "Telugu"),
+                    ("tg", "Tajik"),
+                    ("th", "Thai"),
+                    ("tk", "Turkmen"),
+                    ("tr", "Turkish"),
+                    ("tt", "Tatar"),
+                    ("udm", "Udmurt"),
+                    ("ug", "Uyghur"),
+                    ("uk", "Ukrainian"),
+                    ("ur", "Urdu"),
+                    ("uz", "Uzbek"),
+                    ("vi", "Vietnamese"),
+                    ("zh-hans", "Simplified Chinese"),
+                    ("zh-hant", "Traditional Chinese"),
+                ],
+                default="en",
+                max_length=7,
+            ),
+        ),
+    ]

ram/bookshelf/migrations/0024_issue_magazine_magazineissue.py

@@ -1,226 +0,0 @@
-# Generated by Django 5.2.8 on 2025-11-13 23:01
-
-import bookshelf.models
-import django.db.models.deletion
-import ram.utils
-import tinymce.models
-import uuid
-from django.db import migrations, models
-
-
-class Migration(migrations.Migration):
-
-    dependencies = [
-        ("bookshelf", "0023_delete_basebookdocument"),
-        ("metadata", "0025_alter_company_options_alter_manufacturer_options_and_more"),
-    ]
-
-    operations = [
-        migrations.CreateModel(
-            name="Issue",
-            fields=[
-                (
-                    "basebook_ptr",
-                    models.OneToOneField(
-                        auto_created=True,
-                        on_delete=django.db.models.deletion.CASCADE,
-                        parent_link=True,
-                        primary_key=True,
-                        serialize=False,
-                        to="bookshelf.basebook",
-                    ),
-                ),
-                ("issue_number", models.CharField(max_length=100)),
-            ],
-            options={
-                "abstract": False,
-            },
-            bases=("bookshelf.basebook",),
-        ),
-        migrations.CreateModel(
-            name="Magazine",
-            fields=[
-                (
-                    "uuid",
-                    models.UUIDField(
-                        default=uuid.uuid4,
-                        editable=False,
-                        primary_key=True,
-                        serialize=False,
-                    ),
-                ),
-                ("description", tinymce.models.HTMLField(blank=True)),
-                ("notes", tinymce.models.HTMLField(blank=True)),
-                ("creation_time", models.DateTimeField(auto_now_add=True)),
-                ("updated_time", models.DateTimeField(auto_now=True)),
-                ("published", models.BooleanField(default=True)),
-                ("name", models.CharField(max_length=200)),
-                (
-                    "image",
-                    models.ImageField(
-                        blank=True,
-                        storage=ram.utils.DeduplicatedStorage,
-                        upload_to=bookshelf.models.magazine_image_upload,
-                    ),
-                ),
-                (
-                    "language",
-                    models.CharField(
-                        choices=[
-                            ("af", "Afrikaans"),
-                            ("ar", "Arabic"),
-                            ("ar-dz", "Algerian Arabic"),
-                            ("ast", "Asturian"),
-                            ("az", "Azerbaijani"),
-                            ("bg", "Bulgarian"),
-                            ("be", "Belarusian"),
-                            ("bn", "Bengali"),
-                            ("br", "Breton"),
-                            ("bs", "Bosnian"),
-                            ("ca", "Catalan"),
-                            ("ckb", "Central Kurdish (Sorani)"),
-                            ("cs", "Czech"),
-                            ("cy", "Welsh"),
-                            ("da", "Danish"),
-                            ("de", "German"),
-                            ("dsb", "Lower Sorbian"),
-                            ("el", "Greek"),
-                            ("en", "English"),
-                            ("en-au", "Australian English"),
-                            ("en-gb", "British English"),
-                            ("eo", "Esperanto"),
-                            ("es", "Spanish"),
-                            ("es-ar", "Argentinian Spanish"),
-                            ("es-co", "Colombian Spanish"),
-                            ("es-mx", "Mexican Spanish"),
-                            ("es-ni", "Nicaraguan Spanish"),
-                            ("es-ve", "Venezuelan Spanish"),
-                            ("et", "Estonian"),
-                            ("eu", "Basque"),
-                            ("fa", "Persian"),
-                            ("fi", "Finnish"),
-                            ("fr", "French"),
-                            ("fy", "Frisian"),
-                            ("ga", "Irish"),
-                            ("gd", "Scottish Gaelic"),
-                            ("gl", "Galician"),
-                            ("he", "Hebrew"),
-                            ("hi", "Hindi"),
-                            ("hr", "Croatian"),
-                            ("hsb", "Upper Sorbian"),
-                            ("hu", "Hungarian"),
-                            ("hy", "Armenian"),
-                            ("ia", "Interlingua"),
-                            ("id", "Indonesian"),
-                            ("ig", "Igbo"),
-                            ("io", "Ido"),
-                            ("is", "Icelandic"),
-                            ("it", "Italian"),
-                            ("ja", "Japanese"),
-                            ("ka", "Georgian"),
-                            ("kab", "Kabyle"),
-                            ("kk", "Kazakh"),
-                            ("km", "Khmer"),
-                            ("kn", "Kannada"),
-                            ("ko", "Korean"),
-                            ("ky", "Kyrgyz"),
-                            ("lb", "Luxembourgish"),
-                            ("lt", "Lithuanian"),
-                            ("lv", "Latvian"),
-                            ("mk", "Macedonian"),
-                            ("ml", "Malayalam"),
-                            ("mn", "Mongolian"),
-                            ("mr", "Marathi"),
-                            ("ms", "Malay"),
-                            ("my", "Burmese"),
-                            ("nb", "Norwegian Bokmål"),
-                            ("ne", "Nepali"),
-                            ("nl", "Dutch"),
-                            ("nn", "Norwegian Nynorsk"),
-                            ("os", "Ossetic"),
-                            ("pa", "Punjabi"),
-                            ("pl", "Polish"),
-                            ("pt", "Portuguese"),
-                            ("pt-br", "Brazilian Portuguese"),
-                            ("ro", "Romanian"),
-                            ("ru", "Russian"),
-                            ("sk", "Slovak"),
-                            ("sl", "Slovenian"),
-                            ("sq", "Albanian"),
-                            ("sr", "Serbian"),
-                            ("sr-latn", "Serbian Latin"),
-                            ("sv", "Swedish"),
-                            ("sw", "Swahili"),
-                            ("ta", "Tamil"),
-                            ("te", "Telugu"),
-                            ("tg", "Tajik"),
-                            ("th", "Thai"),
-                            ("tk", "Turkmen"),
-                            ("tr", "Turkish"),
-                            ("tt", "Tatar"),
-                            ("udm", "Udmurt"),
-                            ("ug", "Uyghur"),
-                            ("uk", "Ukrainian"),
-                            ("ur", "Urdu"),
-                            ("uz", "Uzbek"),
-                            ("vi", "Vietnamese"),
-                            ("zh-hans", "Simplified Chinese"),
-                            ("zh-hant", "Traditional Chinese"),
-                        ],
-                        default="en",
-                        max_length=7,
-                    ),
-                ),
-                (
-                    "publisher",
-                    models.ForeignKey(
-                        on_delete=django.db.models.deletion.CASCADE,
-                        to="bookshelf.publisher",
-                    ),
-                ),
-                (
-                    "tags",
-                    models.ManyToManyField(
-                        blank=True, related_name="magazine", to="metadata.tag"
-                    ),
-                ),
-            ],
-            options={
-                "ordering": ["name"],
-            },
-        ),
-        migrations.CreateModel(
-            name="MagazineIssue",
-            fields=[
-                (
-                    "id",
-                    models.BigAutoField(
-                        auto_created=True,
-                        primary_key=True,
-                        serialize=False,
-                        verbose_name="ID",
-                    ),
-                ),
-                (
-                    "issue",
-                    models.ForeignKey(
-                        on_delete=django.db.models.deletion.CASCADE,
-                        related_name="magazine_issue",
-                        to="bookshelf.issue",
-                    ),
-                ),
-                (
-                    "magazine",
-                    models.ForeignKey(
-                        on_delete=django.db.models.deletion.CASCADE,
-                        related_name="magazine_issue",
-                        to="bookshelf.magazine",
-                    ),
-                ),
-            ],
-            options={
-                "ordering": ["magazine", "issue"],
-                "unique_together": {("magazine", "issue")},
-            },
-        ),
-    ]

ram/bookshelf/models.py

@@ -3,7 +3,6 @@ import shutil
 from django.db import models
 from django.conf import settings
 from django.urls import reverse
-from django.utils.dates import MONTHS
 from django_countries.fields import CountryField
 
 from ram.utils import DeduplicatedStorage
@@ -154,62 +153,3 @@ class Catalog(BaseBook):
     def get_scales(self):
         return "/".join([s.scale for s in self.scales.all()])
     get_scales.short_description = "Scales"
-
-
-class Magazine(BaseModel):
-    name = models.CharField(max_length=200)
-    publisher = models.ForeignKey(Publisher, on_delete=models.CASCADE)
-    ISBN = models.CharField(max_length=17, blank=True)  # 13 + dashes
-    image = models.ImageField(
-        blank=True,
-        upload_to=book_image_upload,
-        storage=DeduplicatedStorage,
-    )
-    language = models.CharField(
-        max_length=7,
-        choices=settings.LANGUAGES,
-        default='en'
-    )
-    tags = models.ManyToManyField(
-        Tag, related_name="magazine", blank=True
-    )
-
-    def delete(self, *args, **kwargs):
-        shutil.rmtree(
-            os.path.join(
-                settings.MEDIA_ROOT, "images", "magazines", str(self.uuid)
-            ),
-            ignore_errors=True
-        )
-        super(Magazine, self).delete(*args, **kwargs)
-
-    class Meta:
-        ordering = ["name"]
-
-    def __str__(self):
-        return self.name
-
-    def get_absolute_url(self):
-        return reverse(
-            "bookshelf_item",
-            kwargs={"selector": "magazine", "uuid": self.uuid}
-        )
-
-
-class MagazineIssue(BaseBook):
-    magazine = models.ForeignKey(
-        Magazine, on_delete=models.CASCADE, related_name="issue"
-    )
-    issue_number = models.CharField(max_length=100)
-    publication_month = models.SmallIntegerField(
-        null=True,
-        blank=True,
-        choices=MONTHS.items()
-    )
-
-    class Meta:
-        unique_together = ("magazine", "issue_number")
-        ordering = ["magazine", "issue_number"]
-
-    def __str__(self):
-        return f"{self.magazine.name} - {self.issue.issue_number}"

ram/consist/admin.py

@@ -54,7 +54,7 @@ class ConsistAdmin(SortableAdminBase, admin.ModelAdmin):
     @admin.display(description="Country")
     def country_flag(self, obj):
         return format_html(
-            '<img src="{}" /> {}'.format(obj.country.flag, obj.country)
+            '<img src="{}" /> {}', obj.country.flag, obj.country
         )
 
     fieldsets = (

ram/metadata/admin.py

@@ -54,7 +54,7 @@ class CompanyAdmin(admin.ModelAdmin):
     @admin.display(description="Country")
     def country_flag(self, obj):
         return format_html(
-            '<img src="{}" /> {}'.format(obj.country.flag, obj.country.name)
+            '<img src="{}" /> {}', obj.country.flag, obj.country.name
         )
 
 
@@ -68,7 +68,7 @@ class ManufacturerAdmin(admin.ModelAdmin):
     @admin.display(description="Country")
     def country_flag(self, obj):
         return format_html(
-            '<img src="{}" /> {}'.format(obj.country.flag, obj.country.name)
+            '<img src="{}" /> {}', obj.country.flag, obj.country.name
         )
 
 

ram/portal/templatetags/dcc.py

@@ -1,36 +1,38 @@
 from django import template
 from django.utils.html import format_html
+from django.utils.safestring import mark_safe
 
 register = template.Library()
 
 
 @register.simple_tag
 def dcc(object):
-    socket = (
+    socket = mark_safe(
         '<i class="bi bi-ban small"></i>'
     )
     decoder = ''
     if object.decoder_interface is not None:
-        socket = (
+        socket = mark_safe(
             f'<abbr title="{object.get_decoder_interface()}">'
             f'<i class="bi bi-dice-6"></i></abbr>'
         )
     if object.decoder:
         if object.decoder.sound:
-            decoder = (
+            decoder = mark_safe(
                 f'<abbr title="{object.decoder}">'
                 '<i class="bi bi-volume-up-fill"></i></abbr>'
             )
         else:
-            decoder = (
+            decoder = mark_safe(
                 f'<abbr title="{object.decoder}'
                 f'({object.get_decoder_interface()})">'
                 '<i class="bi bi-cpu-fill"></i></abbr>'
             )
-
     if decoder:
         return format_html(
-            f'{socket} <i class="bi bi-arrow-bar-left"></i>{decoder}'
+            '{} <i class="bi bi-arrow-bar-left"></i> {}',
+            socket,
+            decoder,
         )
 
-    return format_html(socket)
+    return socket

ram/ram/__init__.py

@@ -1,4 +1,4 @@
 from ram.utils import git_suffix
 
-__version__ = "0.17.14"
+__version__ = "0.17.15"
 __version__ += git_suffix(__file__)

ram/ram/utils.py

@@ -48,8 +48,9 @@ def git_suffix(fname):
 
 def get_image_preview(url, max_size=150):
     return format_html(
-        '<img src="{src}" style="max-width: {size}px; max-height: {size}px;'
+        '<img src="{src}" style="max-width: {size}px; max-height: {size}px; background-color: #eee;" />',  # noqa: E501
-        'background-color: #eee;" />'.format(src=url, size=max_size)
+        src=url,
+        size=max_size,
     )
 
 

ram/repository/models.py

@@ -1,11 +1,12 @@
 from django.db import models
+from django.core.exceptions import ValidationError
 
 from tinymce import models as tinymce
 
 from ram.models import PrivateDocument
 from metadata.models import Decoder, Shop, Tag
 from roster.models import RollingStock
-from bookshelf.models import Book, Catalog, Issue
+from bookshelf.models import Book, Catalog
 
 
 class GenericDocument(PrivateDocument):
@@ -76,20 +77,6 @@ class CatalogDocument(PrivateDocument):
         ]
 
 
-class MagazineIssueDocument(PrivateDocument):
-    issue = models.ForeignKey(
-        Issue, on_delete=models.CASCADE, related_name="document"
-    )
-
-    class Meta:
-        verbose_name_plural = "Magazines documents"
-        constraints = [
-            models.UniqueConstraint(
-                fields=["issue", "file"], name="unique_issue_file"
-            )
-        ]
-
-
 class RollingStockDocument(PrivateDocument):
     rolling_stock = models.ForeignKey(
         RollingStock, on_delete=models.CASCADE, related_name="document"

ram/roster/admin.py

@@ -2,7 +2,7 @@ import html
 
 from django.conf import settings
 from django.contrib import admin
-from django.utils.html import format_html, strip_tags
+from django.utils.html import format_html, format_html_join, strip_tags
 
 from adminsortable2.admin import SortableAdminBase, SortableInlineAdminMixin
 
@@ -44,7 +44,7 @@ class RollingClass(admin.ModelAdmin):
     @admin.display(description="Country")
     def country_flag(self, obj):
         return format_html(
-            '<img src="{}" /> {}'.format(obj.country.flag, obj.country)
+            '<img src="{}" /> {}', obj.country.flag, obj.country.name
         )
 
 
@@ -152,7 +152,7 @@ class RollingStockAdmin(SortableAdminBase, admin.ModelAdmin):
     @admin.display(description="Country")
     def country_flag(self, obj):
         return format_html(
-            '<img src="{}" /> {}'.format(obj.country.flag, obj.country)
+            '<img src="{}" /> {}', obj.country.flag, obj.country.name
         )
 
     fieldsets = (
@@ -222,13 +222,14 @@ class RollingStockAdmin(SortableAdminBase, admin.ModelAdmin):
     @admin.display(description="Invoices")
     def invoices(self, obj):
         if obj.invoice.exists():
-            html = "<br>".join(
+            html = format_html_join(
-                "<a href=\"{}\" target=\"_blank\">{}</a>".format(
+                "<br>",
-                    i.file.url, i
+                "<a href=\"{}\" target=\"_blank\">{}</a>",
-                ) for i in obj.invoice.all())
+                ((i.file.url, i) for i in obj.invoice.all())
+            )
         else:
             html = "-"
-        return format_html(html)
+        return html
 
     def download_csv(modeladmin, request, queryset):
         header = [