Feature custom sidecar zero length (#1138)

* Added skip_zero option to --sidecar-template

* Added missing test file

osxphotos/cli/export.py

@@ -348,7 +348,15 @@ from .verbose import get_verbose_console, verbose_print
         [
             click.Path(dir_okay=False, file_okay=True, exists=True),
             TemplateString(),
-            CSVOptions(["write_skipped", "strip_whitespace", "strip_lines", "none"])
+            CSVOptions(
+                [
+                    "write_skipped",
+                    "strip_whitespace",
+                    "strip_lines",
+                    "skip_zero",
+                    "none",
+                ]
+            ),
         ]
     ),
     help="Create a custom sidecar file for each photo exported with user provided Mako template (MAKO_TEMPLATE_FILE). "
@@ -361,11 +369,12 @@ from .verbose import get_verbose_console, verbose_print
     "The `{filepath}` template variable may be used in the SIDECAR_FILENAME_TEMPLATE to refer to the filename of the "
     "photo being exported. "
     "OPTIONS is a comma-separated list of strings providing additional options to the template. "
-    "Valid options are: write_skipped, strip_whitespace, strip_lines, none. "
+    "Valid options are: write_skipped, strip_whitespace, strip_lines, skip_zero, none. "
     "write_skipped will cause the sidecar file to be written even if the photo is skipped during export. "
     "If write_skipped is not passed as an option, the sidecar file will not be written if the photo is skipped during export. "
     "strip_whitespace and strip_lines indicate whether or not to strip whitespace and blank lines, respectively, "
     "from the resulting sidecar file. "
+    "skip_zero causes the sidecar file to be skipped if the rendered template is zero-length. "
     "For example, to create a sidecar file with extension .xmp using a template file named 'sidecar.mako' "
     "and write a sidecar for skipped photos and strip blank lines but not whitespace: "
     "`--sidecar-template sidecar.mako '{filepath}.xmp' write_skipped,strip_lines`. "

osxphotos/cli/sidecar.py

@@ -53,6 +53,7 @@ def generate_user_sidecar(
         strip_whitespace = "strip_whitespace" in options
         strip_lines = "strip_lines" in options
         write_skipped = "write_skipped" in options
+        skip_zero = "skip_zero" in options
 
         if not write_skipped:
             # skip writing sidecar if photo not exported
@@ -97,6 +98,8 @@ def generate_user_sidecar(
                 filepath=filepath,
                 strip_whitespace=strip_whitespace,
                 strip_lines=strip_lines,
+                skip_zero=skip_zero,
+                verbose=verbose,
                 dry_run=dry_run,
             )
             sidecar_results.sidecar_user_written.append(template_filename)
@@ -129,6 +132,8 @@ def _render_sidecar_and_write_data(
     filepath: str,
     strip_whitespace: bool,
     strip_lines: bool,
+    skip_zero: bool,
+    verbose: Callable[..., None],
     dry_run: bool,
 ):
     """Render sidecar template and write data to file"""
@@ -149,5 +154,8 @@ def _render_sidecar_and_write_data(
         )
     if not dry_run:
         # write sidecar file
+        if skip_zero and not sidecar_data:
+            verbose(f"Skipping empty sidecar file [filepath]{template_filename}[/]")
+            return
         with open(template_filename, "w") as f:
             f.write(sidecar_data)

tests/custom_sidecar_zero.mako

@@ -0,0 +1,3 @@
+<%doc> custom mako sidecar template that renders to zero length for some photos; use with options
+    "strip_whitespace,strip_lines,skip_zero" </%doc>
+${",".join(photo.keywords)}

tests/test_cli_export_sidecar_template.py

@@ -33,6 +33,9 @@ Sidecar: wedding.jpg.sidecar
     Rating: ★★★★★
 """
 
+PHOTO_UUID_NO_KEYWORD = "4D521201-92AC-43E5-8F7C-59BC41C37A96"  # IMG_1997.CR2
+SIDECAR_FILENAME_NO_KEYWORD = "IMG_1997.CR2.txt"
+
 
 def test_export_sidecar_template_1():
     """test basic export with --sidecar-template"""
@@ -61,6 +64,7 @@ def test_export_sidecar_template_1():
         sidecar_data = sidecar_file.read_text()
         assert sidecar_data == SIDECAR_DATA
 
+
 def test_export_sidecar_template_option_case():
     """test basic export with --sidecar-template and option case insensitivity"""
     runner = CliRunner()
@@ -89,7 +93,6 @@ def test_export_sidecar_template_option_case():
         assert sidecar_data == SIDECAR_DATA
 
 
-
 def test_export_sidecar_template_strip_whitespace():
     """test basic export with --sidecar-template and STRIP_WHITESPACE = True"""
     runner = CliRunner()
@@ -182,6 +185,7 @@ def test_export_sidecar_template_strip_lines_strip_whitespace():
         )
         assert sidecar_data == sidecar_expected
 
+
 def test_export_sidecar_template_strip_lines_strip_whitespace_option_space():
     """test basic export with --sidecar-template and STRIP_LINES = True and STRIP_WHITESPACE = True with space in option"""
     runner = CliRunner()
@@ -212,6 +216,7 @@ def test_export_sidecar_template_strip_lines_strip_whitespace_option_space():
         )
         assert sidecar_data == sidecar_expected
 
+
 def test_export_sidecar_template_update_no():
     """test basic export with --sidecar-template and WRITE_SKIPPED = False, also test --cleanup"""
     runner = CliRunner()
@@ -505,3 +510,37 @@ def test_export_sidecar_template_full_library():
             ],
         )
         assert result.exit_code == 0
+
+
+def test_export_sidecar_template_skip_zero():
+    """test basic export with --sidecar-template with skip_zero option"""
+    runner = CliRunner()
+    cwd = os.getcwd()
+    # pylint: disable=not-context-manager
+    with runner.isolated_filesystem():
+        result = runner.invoke(
+            export,
+            [
+                "--library",
+                os.path.join(cwd, PHOTOS_DB),
+                ".",
+                "-V",
+                "--uuid",
+                PHOTO_UUID,
+                "--uuid",
+                PHOTO_UUID_NO_KEYWORD,
+                "--sidecar-template",
+                os.path.join(cwd, "tests", "custom_sidecar_zero.mako"),
+                "{filepath}.txt",
+                "strip_whitespace,strip_lines,skip_zero",
+            ],
+        )
+        assert result.exit_code == 0
+
+        assert "Skipping empty sidecar file" in result.output
+
+        sidecar_file = pathlib.Path(SIDECAR_FILENAME)
+        assert sidecar_file.exists()
+
+        sidecar_file = pathlib.Path(SIDECAR_FILENAME_NO_KEYWORD)
+        assert not sidecar_file.exists()