Update MetadataFormatter

Several custom conversions (the s in {title!s}) have been created
u - str.upper()
l - str.casefold()
S - str.swapcase()
t - str.title()
c - str.Capitalize()

A new syntax has been added '{title+str}' and '{title-str}':
The + indicates an alternate value.
The - indicates a default value.

If the title of a comic is not set then
'{title-str}' will output 'str'
and
'{title+str} will output ''

If the title of a comic is 'hello' then
'{title+str}' will output 'str'
and
'{title-str}' will output 'hello'

comictaggerlib/filerenamer.py

@@ -79,12 +79,39 @@ class MetadataFormatter(string.Formatter):
             return ""
         return cast(str, super().format_field(value, format_spec))
 
+    def convert_field(self, value: Any, conversion: str) -> str:
+        if conversion == "u":
+            return str(value).upper()
+        if conversion == "l":
+            return str(value).casefold()
+        if conversion == "c":
+            return str(value).capitalize()
+        if conversion == "S":
+            return str(value).swapcase()
+        if conversion == "t":
+            return str(value).title()
+        return cast(str, super().convert_field(value, conversion))
+
     def handle_replacements(self, string: str, replacements: list[Replacement]) -> str:
         for find, replace, strict_only in replacements:
             if self.is_strict() or not strict_only:
                 string = string.replace(find, replace)
         return string
 
+    def none_replacement(self, value: Any, replacement: str, r: str) -> Any:
+        if r == "-" and value is None or value == "":
+            return replacement
+        if r == "+" and value is not None:
+            return replacement
+        return value
+
+    def split_replacement(self, field_name: str) -> tuple[str, str, str]:
+        if "-" in field_name:
+            return field_name.rpartition("-")
+        if "+" in field_name:
+            return field_name.rpartition("+")
+        return field_name, "", ""
+
     def is_strict(self) -> bool:
         return self.platform in [Platform.UNIVERSAL, Platform.WINDOWS]
 
@@ -124,6 +151,7 @@ class MetadataFormatter(string.Formatter):
             lstrip = False
             # if there's a field, output it
             if field_name is not None and field_name != "":
+                field_name, r, replacement = self.split_replacement(field_name)
                 field_name = field_name.casefold()
                 # this is some markup, find the object and do the formatting
 
@@ -136,6 +164,8 @@ class MetadataFormatter(string.Formatter):
                 obj, arg_used = self.get_field(field_name, args, kwargs)
                 used_args.add(arg_used)
 
+                obj = self.none_replacement(obj, replacement, r)
+
                 # do any conversion on the resulting object
                 obj = self.convert_field(obj, conversion)  # type: ignore
 

testing/filenames.py

@@ -750,6 +750,76 @@ fnames = [
 ]
 
 rnames = [
+    (
+        "{series!c} {price} {year}",  # Capitalize
+        False,
+        "universal",
+        "Cory doctorow's futuristic tales of the here and now 2007.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{series!t} {price} {year}",  # Title Case
+        False,
+        "universal",
+        "Cory Doctorow'S Futuristic Tales Of The Here And Now 2007.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{series!S} {price} {year}",  # Swap Case
+        False,
+        "universal",
+        "cORY dOCTOROW'S fUTURISTIC tALES OF THE hERE AND nOW 2007.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{title!l} {price} {year}",  # Lowercase
+        False,
+        "universal",
+        "anda's game 2007.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{title!u} {price} {year}",  # Upper Case
+        False,
+        "universal",
+        "ANDA'S GAME 2007.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{title} {price} {year+}",  # Empty alternate value
+        False,
+        "universal",
+        "Anda's Game.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{title} {price} {year+year!u}",  # Alternate value Upper Case
+        False,
+        "universal",
+        "Anda's Game YEAR.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{title} {price} {year+year}",  # Alternate Value
+        False,
+        "universal",
+        "Anda's Game year.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{title} {price-0} {year}",  # Default value
+        False,
+        "universal",
+        "Anda's Game 0 2007.cbz",
+        does_not_raise(),
+    ),
+    (
+        "{title} {price+0} {year}",  # Alternate Value
+        False,
+        "universal",
+        "Anda's Game 2007.cbz",
+        does_not_raise(),
+    ),
     (
         "{series} #{issue} - {title} ({year}) ({price})",  # price should be none
         False,