Use {title} - {authors} as the default download template

This is Calibre's default. An empty template now restores the default.

README.md

@@ -447,10 +447,12 @@ downloaded before.
 
 ## File names of downloaded books
 
-"Download ePub" on a story page sends the book to your browser with a file name. Without a template,
-the name is the title, for example `The Book.epub`.
+"Download ePub" on a story page sends the book to your browser with a file name. A template gives
+the name. The default template is `{title} - {authors}`, as in Calibre. For "The Book" by Ann
+Writer, it gives `Book, The - Ann Writer.epub`.
 
-An admin can set a template for the name under "Book Downloads" in Settings. The template follows
+An admin can change the template under "Book Downloads" in Settings. To go back to the default,
+clear the field and save. The template follows
 the rules of [Calibre's templates](https://manual.calibre-ebook.com/template_lang.html) for file
 names, so a template from Calibre gives the same name in Bindery. Bindery adds `.epub`. For example,
 `{series:|| - }{series_index:0>2s|| - }{title} - {authors}` gives

bindery/filename_template.py

@@ -15,6 +15,8 @@ from typing import Any
 
 from bindery.ingest import sanitize_filename
 
+# Calibre's default template for a file that it sends to a device.
+DEFAULT_TEMPLATE = "{title} - {authors}"
 MAX_TEMPLATE_LENGTH = 1024
 # The most characters that a format can ask for, as a width or a precision.
 MAX_WIDTH = 255

bindery/orchestrator.py

@@ -380,7 +380,7 @@ def get_settings() -> dict[str, Any]:
         "linking_available": _linking_available(),
         "hold_new_links": bool(store.get_setting(None, "hold_new_links")),
         "personal_ini": ini.read_text(encoding="utf-8") if ini.exists() else "",
-        "download_template": store.get_setting(None, "download_template") or "",
+        "download_template": _download_template(),
         **job_list_settings(),
     }
 
@@ -648,20 +648,22 @@ def download_fields() -> dict[str, str]:
     return fields
 
 
+def _download_template() -> str:
+    return store.get_setting(None, "download_template") or filename_template.DEFAULT_TEMPLATE
+
+
 def _download_name(story: dict[str, Any]) -> str:
-    """The file name of a downloaded book. It comes from the download template. Without a template, or if the
-    template fails or gives no name for this book, it is the title."""
-    template = store.get_setting(None, "download_template")
-    name = ""
-    if template:
+    """The file name of a downloaded book, from the download template. If the template fails or gives no name for
+    this book, the name is the title."""
     meta = _book_metadata(story["site_values"], _epub_overrides(story["pinned"]))
     meta["title"] = meta.get("title") or story["title"]
     meta["authors"] = meta.get("authors") or [story["author"]]
     meta.update(publisher=story["site"], timestamp=story["created_at"], last_modified=story["last_changed"])
     # Without CWA, the saved CWA book IDs do not apply.
     book_id = story["calibre_id"] if config.CWA_ENABLED and story["calibre_id"] is not None else story["id"]
+    name = ""
     try:
-            name = filename_template.file_name(template, filename_template.prepare(meta, book_id))
+        name = filename_template.file_name(_download_template(), filename_template.prepare(meta, book_id))
     except filename_template.TemplateError as e:
         logger.warning(f"The download template fails for {story['url']}: {e}")
     return f"{name or sanitize_filename(story['title'])}.epub"

bindery/static/js/settings.js

@@ -162,7 +162,8 @@ export function settingsPage(main, _params, config) {
         'This template gives the file name of a book that you download from a story page. It follows the ',
         externalLink(TEMPLATE_DOCS, 'template rules of Calibre'),
         ' for file names. Bindery replaces each field in braces with the value of the book, and adds .epub. ' +
-          'A field with no value becomes empty text. Leave the template empty to name the file after the title. ' +
+          'A field with no value becomes empty text. To go back to the default, {title} - {authors}, clear the field ' +
+          'and save. ' +
           'For example, ',
         code('{series:|| - }{series_index:0>2s|| - }{title} - {authors}'),
         ' gives "Saga, The - 02 - Book, The - Ann Writer.epub".',

tests/test_api.py

@@ -472,7 +472,7 @@ def test_settings(client, monkeypatch, tmp_path):
         "pause_uploads": False,
         "ingest_available": True,
         "personal_ini": "[defaults]\nis_adult:true\n",
-        "download_template": "",
+        "download_template": "{title} - {authors}",
         "story_jobs_hours": 36,
         "story_jobs_count": 10,
         "main_jobs_hours": 6,

tests/test_api_flows.py

@@ -142,7 +142,7 @@ def test_download_builds_from_stored_chapters_without_changing_them(client, stor
     response = client.get(f"/api/stories/{sid}/epub")
     assert response.status_code == 200
     assert response.data.startswith(b"PK")
-    assert "filename=A_B.epub" in response.headers["Content-Disposition"]
+    assert 'filename="A_B - Writer.epub"' in response.headers["Content-Disposition"]
     assert o.store.revision_html(cid, 1) == original
     response.close()
 
@@ -166,11 +166,12 @@ def test_download_template_names_the_file(client, story):
     name = download_name(client, sid)
     assert 'filename="Cafe - 77.epub"' in name and "filename*=UTF-8''Caf%C3%A9%20-%2077.epub" in name
     # A template with folders gives the name of the file alone.
-    client.put("/api/settings", json={"download_template": "{author_sort}/{title} - {authors}"}, headers=H)
+    client.put("/api/settings", json={"download_template": "{author_sort}/{title}"}, headers=H)
+    assert "filename*=UTF-8''Caf%C3%A9.epub" in download_name(client, sid)
+    # An empty template restores the default.
+    saved = client.put("/api/settings", json={"download_template": " "}, headers=H).json
+    assert saved["download_template"] == "{title} - {authors}"
     assert "filename*=UTF-8''Caf%C3%A9%20-%20Ann%20Writer.epub" in download_name(client, sid)
-    # Without a template, the name is the title of the story, with its article in front.
-    assert client.put("/api/settings", json={"download_template": ""}, headers=H).json["download_template"] == ""
-    assert 'filename="The Book.epub"' in download_name(client, sid)
 
 
 def test_download_template_that_fails_gives_the_title(client, story, caplog):