fe9156adb8aeb3add4a73a06c7ace15c2d246da8
chmalee
  Thu Apr 11 10:59:28 2019 -0700
Python api client is slightly more robust, and should correctly report error responses from the api, refs #18869

diff --git src/hg/hubApi/tests/pythonClient.py src/hg/hubApi/tests/pythonClient.py
index 7d30ac0..2822ed2 100755
--- src/hg/hubApi/tests/pythonClient.py
+++ src/hg/hubApi/tests/pythonClient.py
@@ -1,68 +1,115 @@
 #!/bin/env python
 
 """
 This code is heavily inspired by the Ensembl python client
 """
 import argparse
 import json
 import sys
 
 # support python2 and 3
 try:
     from urllib.parse import urlparse, urlencode
     from urllib.request import urlopen, Request
     from urllib.error import HTTPError
 except ImportError:
     from urlparse import urlparse
     from urllib import urlencode
     from urllib2 import urlopen, Request, HTTPError
 
 serverName = "https://api-test.gi.ucsc.edu"
-endpoints = ["list", "getData"]
-parameterList = ["hubUrl", "genome", "db", "track", "chrom", "start", "end", "maxItemsOutput", "trackLeavesOnly"]
+endpoints = ["/list/publicHubs", "/list/ucscGenomes", "/list/hubGenomes",
+    "/list/tracks", "/list/chromosomes", "/getData/sequence", "/getData/track"]
+parameterList = ["hubUrl", "genome", "db", "track", "chrom", "start", "end",
+    "maxItemsOutput", "trackLeavesOnly"]
 
 def parseCommandLine():
-    parser = argparse.ArgumentParser(formatter_class=argparse.RawDescriptionHelpFormatter, description="Test accessing UCSC Genome Browser API",
-        epilog="Example usage:\npythonClient.py \"/getData/track\" \"track=gold;db=hg38;chrom=chrM;maxItemsOutput=2\"")
-    parser.add_argument("endpoint", help="endpoint string like \"/list/tracks\" or \"/getData/track/\"", type=str)
-    parser.add_argument("parameters", help="semi-colon separated, required and/or optional endpoint argument(s) like \"db=hg38;chrom=chrM;maxItemsOutput=2\"",type=str)
-    parser.add_argument("-p", "--pretty-print", action="store_true", default=False)
-    if len(sys.argv) <= 2:
-        parser.print_help()
-        sys.exit(1)
-    else:
-        return parser.parse_args()
+    parser = argparse.ArgumentParser(formatter_class=argparse.RawDescriptionHelpFormatter,
+        description="Test accessing UCSC Genome Browser API",
+        epilog="Example usage:\npythonClient.py \"/getData/track\" "
+        "\"track=gold;db=hg38;chrom=chrM;maxItemsOutput=2\"")
+    parser.add_argument("endpoint", nargs='?',
+        help="Endpoint string like \"/list/tracks\" or \"/getData/track/\"", type=str)
+    parser.add_argument("parameters", nargs='?',
+        help="Parameters to endpoints. semi-colon separated key=value formatted string, "
+        "like \"db=hg38;chrom=chrM;maxItemsOutput=2\"",type=str)
+    parser.add_argument("-p", "--pretty-print", action="store_true", default=False,
+        help="Print json response with newlines")
+    parser.add_argument("--show-endpoints", action="store_true", default=False,
+        help="List the supported endpoints")
+    parser.add_argument("--show-arguments", action="store_true", default=False,
+        help="List the supported arguments")
+    parser.add_argument("--debug", action="store_true", default=False,
+        help="Print final URL of the request.")
+    return parser
 
 def main():
-    args = parseCommandLine()
+    cmd = parseCommandLine()
+    args = cmd.parse_args()
+    req =  serverName
+
+    if len(sys.argv) == 1:
+        cmd.print_help()
+        sys.exit(0)
+
+    # check for the show arguments first and exit early
+    if args.show_endpoints:
+        print("Currently supported endpoints:\n\t%s" % ("\n\t".join(endpoints)))
+        sys.exit(0)
+    if args.show_arguments:
+        print("Currently supported parameters to endpoint functions:\n\t%s" %
+            ("\n\t".join(parameterList)))
+        sys.exit(0)
 
     # check endpoints
-    if not args.endpoint.startswith("/list") and not args.endpoint.startswith("/getData"):
-        raise Exception("The only supported endpoints are '/list' and '/getData'\n")
+    if args.endpoint:
+        if args.endpoint not in endpoints:
+            sys.stderr.write("Error: Endpoint '%s' not supported.\n"
+                "Currently supported endpoints are:\n\t%s\n\n" %
+                (args.endpoint, "\n\t".join(endpoints)))
+            cmd.print_help()
+            sys.exit(1)
+        req += args.endpoint
 
-    #  check params formatted specifically
+    # check params formatted correctly
+    if args.parameters:
         params = args.parameters.split(";")
         for param in params:
             arg = param.split("=")[0]
             if arg == param or arg not in parameterList:
-            raise Exception("Unsupported parameter %s. Please format parameters as arg=val.\n" % arg)
+                sys.stderr.write("Unsupported parameter '%s'. "
+                    "Currently supported parameters to endpoints:\n\t%s\n"
+                    "Please format parameters as arg=val.\n\n" %
+                    (arg, "\n\t".join(parameterList)))
+                cmd.print_help()
+                sys.exit(1)
+        req += "?" + args.parameters
 
     # make http request and print the output
     data = None
-    req = serverName + args.endpoint + "?" + args.parameters
-    print("trying request: %s\n" % req)
+    if args.debug:
+        print("request URL: %s\n" % req)
     try:
         request = Request(req)
         response = urlopen(request)
         content = response.read()
         if content:
             data = json.loads(content)
     except HTTPError as e:
-        raise Exception("Request %s failed with HTTP status %s" % (req, e.code))
+        if e.code == 400: # does this work for other status codes?
+            data = json.loads(e.read())
+            sys.stderr.write("Error: %s\n" % data["error"])
+            sys.exit(1)
+        else:
+            sys.stderr.write("Request %s failed with HTTP status %s\nreason:%s\n" %
+                (req, e.code, e.reason))
+        sys.exit(1)
+
+    if data:
         if args.pretty_print:
             print(json.dumps(data, indent=4, separators=(",",":")))
         else:
             print(json.dumps(data))
 
 if __name__ == "__main__":
     main()