Add better feedback for broken files

src/biokeen/cli_utils/bio_2_bel_utils.py

@@ -5,6 +5,7 @@
 import importlib
 import os
 import sys
+from typing import Optional
 
 import click
 import pkg_resources
@@ -42,7 +43,7 @@ def _import_bio2bel_module(package: str):
     return b_module
 
 
-def install_bio2bel_module(name, connection, rebuild):
+def install_bio2bel_module(name: str, connection: str, rebuild: bool) -> Optional[str]:
     """Install Bio2BEL module."""
     if name == 'compath':  # special case for compath
         module_name = 'compath_resources'
@@ -83,10 +84,15 @@ def install_bio2bel_module(name, connection, rebuild):
 
     click.secho(f'{EMOJI} generating BEL for {module_name}', bold=True)
     graph = manager.to_bel()
+
     click.echo(f'Summary: {graph.number_of_nodes()} nodes / {graph.number_of_edges()} edges')
     to_json_path(graph, json_path, indent=2)
+
     click.secho(f'{EMOJI} generating PyKEEN TSV for {module_name}', bold=True)
-    to_pykeen_file(graph, pykeen_df_path)
-    click.secho(f'{EMOJI} wrote PyKEEN TSV to {pykeen_df_path}', bold=True)
+    success = to_pykeen_file(graph, pykeen_df_path)
+
+    if success:
+        click.secho(f'{EMOJI} wrote PyKEEN TSV to {pykeen_df_path}', bold=True)
+        return pykeen_df_path
 
-    return pykeen_df_path
+    click.secho(f'{EMOJI} no statements generated', bold=True, fg='red')

src/biokeen/convert/io.py

@@ -27,10 +27,15 @@
 logger = logging.getLogger(__name__)
 
 
-def to_pykeen_file(graph: BELGraph, file: Union[str, Path, TextIO]) -> None:
+def to_pykeen_file(graph: BELGraph, file: Union[str, Path, TextIO]) -> bool:
     """Write the relationships in the BEL graph to a KEEN TSV file."""
     df = to_pykeen_df(graph)
+
+    if len(df.index) == 0:
+        return False
+
     df.to_csv(file, sep='\t', index=None, header=None)
+    return True
 
 
 def to_pykeen_df(graph: BELGraph) -> pd.DataFrame: