adding example option for cli

json_explorer/cli.py

@@ -5,7 +5,7 @@
 import webbrowser
 from http.server import BaseHTTPRequestHandler, HTTPServer
 
-from .explore import TripleCounter
+from .explore import THIS_DIR, TripleCounter
 
 
 def start_browser(server_ready_event, url):
@@ -21,19 +21,43 @@ def jsonl_iterator(filename):
 
 def main():
     parser = argparse.ArgumentParser(
-        prog="ProgramName",
-        description="What the program does",
-        epilog="Text at the bottom of help",
+        description="visualize the structure and type of a group of JSONs",
     )
     parser.add_argument(
         "filename",
         help="filename of a file in JSON Lines format",
+        nargs="?",
+        default=None,
+    )
+    parser.add_argument(
+        "--example",
+        help="run with test data",
+        action="store_true",
+    )
+    parser.add_argument(
+        "-p",
+        "--port",
+        default=8001,
+        type=int,
+        help="port for server (default 8001)",
+    )
+    parser.add_argument(
+        "-n",
+        "--no-serve",
+        help="write HTML to stdout instead of opening browser",
+        action="store_true",
     )
-    parser.add_argument("-p", "--port", default=8001, type=int, help="port for server (default 8001)")
-    parser.add_argument("-n", "--no-serve", help="write HTML to stdout instead of serving", action="store_true")
     args = parser.parse_args()
 
-    counter = TripleCounter.from_objects(jsonl_iterator(args.filename))
+    filename = args.filename
+    if not args.example and not args.filename:
+        parser.error("filename is required (unless --example is given)")
+    elif args.example and args.filename:
+        parser.error("can't pass both filename and --example")
+    elif args.example:
+        filename = THIS_DIR / "example1.jsonl"
+
+    counter = TripleCounter.from_objects(jsonl_iterator(filename))
     response_text = counter.html()
 
     if args.no_serve: