Added {function} template, #419

osxphotos/_version.py

@@ -1,3 +1,3 @@
 """ version info """
 
-__version__ = "0.42.00"
+__version__ = "0.42.1"

osxphotos/phototemplate.md

@@ -60,7 +60,7 @@ e.g. If Photo is in `Album1` in `Folder1`:
 - `"{folder_album(>)}"` renders to `["Folder1>Album1"]`
 - `"{folder_album()}"` renders to `["Folder1Album1"]`
 
-`[find|replace]`: optional text replacement to perform on rendered template value.  For example, to replace "/" in an album name, you could use the template `"{album[/,-]}"`.  Multiple replacements can be made by appending "|" and adding another find|replace pair.  e.g. to replace both "/" and ":" in album name: `"{album[/,-|:,-]}"`.  find/replace pairs are not limited to single characters.  The "|" character cannot be used in a find/replace pair.
+`[find,replace]`: optional text replacement to perform on rendered template value.  For example, to replace "/" in an album name, you could use the template `"{album[/,-]}"`.  Multiple replacements can be made by appending "|" and adding another find|replace pair.  e.g. to replace both "/" and ":" in album name: `"{album[/,-|:,-]}"`.  find/replace pairs are not limited to single characters.  The "|" character cannot be used in a find/replace pair.
 
 `conditional`: optional conditional expression that is evaluated as boolean (True/False) for use with the `?bool_value` modifier.  Conditional expressions take the form '` not operator value`' where `not` is an optional modifier that negates the `operator`.  Note: the space before the conditional expression is required if you use a conditional expression.  Valid comparison operators are:
 

osxphotos/phototemplate.py

@@ -11,6 +11,7 @@ from ._constants import _UNKNOWN_PERSON
 from .datetime_formatter import DateTimeFormatter
 from .exiftool import ExifTool
 from .path_utils import sanitize_dirname, sanitize_filename, sanitize_pathpart
+from .utils import load_function
 
 # ensure locale set to user's locale
 locale.setlocale(locale.LC_ALL, "")
@@ -152,6 +153,10 @@ TEMPLATE_SUBSTITUTIONS_MULTI_VALUED = {
     + "For example: '{photo.favorite}' is the same as '{favorite}' and '{photo.place.name}' is the same as '{place.name}'. "
     + "'{photo}' provides access to properties that are not available as separate template fields but it assumes some knowledge of "
     + "the underlying PhotoInfo class.  See https://rhettbull.github.io/osxphotos/ for additional documentation on the PhotoInfo class.",
+    "{function}": "Execute a python function from an external file and use return value as template substitution. "
+    + "Use in format: {function:file.py::function_name} where 'file.py' is the name of the python file and 'function_name' is the name of the function to call. "
+    + "The function will be passed the PhotoInfo object for the photo. "
+    + "See https://github.com/RhetTbull/osxphotos/blob/master/examples/template_function.py for an example of how to implement a template function.",
 }
 
 FILTER_VALUES = {
@@ -463,6 +468,14 @@ class PhotoTemplate:
                 vals = self.get_template_value_exiftool(
                     subfield, filename=filename, dirname=dirname
                 )
+            elif field == "function":
+                if subfield is None:
+                    raise ValueError(
+                        "SyntaxError: filename and function must not be null with {function::filename.py:function_name}"
+                    )
+                vals = self.get_template_value_function(
+                    subfield, filename=filename, dirname=dirname
+                )
             elif field in MULTI_VALUE_SUBSTITUTIONS or field.startswith("photo"):
                 vals = self.get_template_value_multi(
                     field, path_sep=path_sep, filename=filename, dirname=dirname
@@ -1064,6 +1077,39 @@ class PhotoTemplate:
 
         return values
 
+    def get_template_value_function(self, subfield, filename=None, dirname=None):
+        """Get template value from external function """
+
+        if "::" not in subfield:
+            raise ValueError(
+                f"SyntaxError: could not parse function name from '{subfield}'"
+            )
+
+        filename, funcname = subfield.split("::")
+
+        print(filename, funcname)
+
+        if not pathlib.Path(filename).is_file():
+            raise ValueError(f"'{filename}' does not appear to be a file")
+
+        template_func = load_function(filename, funcname)
+        values = template_func(self.photo)
+
+        if not isinstance(values, (str, list)):
+            raise TypeError(
+                f"Invalid return type for function {funcname}: expected str or list"
+            )
+        if type(values) == str:
+            values = [values]
+
+        # sanitize directory names if needed
+        if filename:
+            values = [sanitize_pathpart(value) for value in values]
+        elif dirname:
+            values = [sanitize_dirname(value) for value in values]
+
+        return values
+
     def get_photo_video_type(self, default):
         """ return media type, e.g. photo or video """
         default_dict = parse_default_kv(default, PHOTO_VIDEO_TYPE_DEFAULTS)

osxphotos/phototemplate.tx

@@ -51,6 +51,10 @@ Field:
     FIELD_WORD+
 ;
 
+FIELD_WORD:
+    /[\.\w]+/
+;
+
 SubField:
     (
     ":"-
@@ -58,12 +62,8 @@ SubField:
     )?
 ;
 
-FIELD_WORD:
-    /[\.\w]+/
-;
-
 SUBFIELD_WORD:
-    /[\.\w:]+/
+    /[\.\w:\/]+/
 ;
 
 Filter:

osxphotos/utils.py

@@ -1,5 +1,8 @@
+""" Utility functions used in osxphotos """
+
 import fnmatch
 import glob
+import importlib
 import inspect
 import logging
 import os
@@ -13,6 +16,7 @@ import sys
 import unicodedata
 import urllib.parse
 from plistlib import load as plistload
+from typing import Callable
 
 import CoreFoundation
 import CoreServices
@@ -401,3 +405,28 @@ def increment_filename(filepath):
         count += 1
     dest = dest.parent / f"{dest_new}{dest.suffix}"
     return str(dest)
+
+
+def load_function(pyfile: str, function_name: str) -> Callable:
+    """ Load function_name from python file pyfile """
+    module_file = pathlib.Path(pyfile)
+    if not module_file.is_file():
+        raise FileNotFoundError(f"module {pyfile} does not appear to exist")
+
+    module_dir = module_file.parent or pathlib.Path(os.getcwd())
+    module_name = module_file.stem
+
+    # store old sys.path and ensure module_dir at beginning of path
+    syspath = sys.path
+    sys.path = [str(module_dir)] + syspath
+    module = importlib.import_module(module_name)
+
+    try:
+        func = getattr(module, function_name)
+    except AttributeError:
+        raise ValueError(f"'{function_name}' not found in module '{module_name}'")
+    finally:
+        # restore sys.path
+        sys.path = syspath
+
+    return func