Adds conditional import handling for OMERO file source

Author: davelopez

lib/galaxy/files/sources/omero.py

@@ -6,9 +6,6 @@
     Union,
 )
 
-import omero.sys
-from omero.gateway import BlitzGateway
-
 from galaxy.exceptions import (
     AuthenticationFailed,
     ObjectNotFound,
@@ -27,6 +24,13 @@
 )
 from galaxy.util.config_templates import TemplateExpansion
 
+try:
+    import omero.sys
+    from omero.gateway import BlitzGateway
+except ImportError:
+    omero = None
+    BlitzGateway = None
+
 
 class OmeroFileSourceTemplateConfiguration(BaseFileSourceTemplateConfiguration):
     username: Union[str, TemplateExpansion]
@@ -47,20 +51,34 @@ class OmeroFileSource(BaseFilesSource[OmeroFileSourceTemplateConfiguration, Omer
     plugin_kind = PluginKind.rfs
     supports_pagination = True
     supports_search = True
+    required_module = BlitzGateway
+    required_package = "omero-py (requires manual Zeroc IcePy installation)"
 
     template_config_class = OmeroFileSourceTemplateConfiguration
     resolved_config_class = OmeroFileSourceConfiguration
 
     def __init__(self, template_config: OmeroFileSourceTemplateConfiguration):
+        if self.required_module is None:
+            raise self.required_package_exception
         super().__init__(template_config)
 
+    @property
+    def required_package_exception(self) -> Exception:
+        return Exception(
+            f"The Python package '{self.required_package}' is required to use this file source plugin. "
+            "Please see https://omero.readthedocs.io/en/stable/developers/Python.html for installation instructions."
+        )
+
     @contextmanager
     def _connection(self, context: FilesSourceRuntimeContext[OmeroFileSourceConfiguration]) -> Iterator[BlitzGateway]:
         """Context manager for OMERO connections with automatic cleanup.
 
         Establishes a connection to the OMERO server, enables keepalive for long-running
         operations, and ensures proper cleanup on exit.
         """
+        if BlitzGateway is None:
+            raise self.required_package_exception
+
         conn = BlitzGateway(
             username=context.config.username,
             passwd=context.config.password,