Add example for querying metadata API (#895)

Author: vogelsgesang

samples/metadata_query.py

@@ -0,0 +1,64 @@
+####
+# This script demonstrates how to use the metadata API to query information on a published data source
+#
+# To run the script, you must have installed Python 3.5 or later.
+####
+
+import argparse
+import logging
+from pprint import pprint
+
+import tableauserverclient as TSC
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Use the metadata API to get information on a published data source.')
+    # Common options; please keep those in sync across all samples
+    parser.add_argument('--server', '-s', required=True, help='server address')
+    parser.add_argument('--site', '-S', help='site name')
+    parser.add_argument('--token-name', '-n', required=True,
+                        help='name of the personal access token used to sign into the server')
+    parser.add_argument('--token-value', '-v', required=True,
+                        help='value of the personal access token used to sign into the server')
+    parser.add_argument('--logging-level', '-l', choices=['debug', 'info', 'error'], default='error',
+                        help='desired logging level (set to error by default)')
+    # Options specific to this sample
+    parser.add_argument('datasource_name', nargs='?', help="The name of the published datasource. If not present, we query all data sources.")
+
+
+    args = parser.parse_args()
+
+    # Set logging level based on user input, or error by default
+    logging_level = getattr(logging, args.logging_level.upper())
+    logging.basicConfig(level=logging_level)
+
+    # Sign in to server
+    tableau_auth = TSC.PersonalAccessTokenAuth(args.token_name, args.token_value, site_id=args.site)
+    server = TSC.Server(args.server, use_server_version=True)
+    with server.auth.sign_in(tableau_auth):
+        # Execute the query
+        result = server.metadata.query("""
+            query useMetadataApiToQueryOrdersDatabases($name: String){
+                publishedDatasources (filter: {name: $name}) {
+                    luid
+                    name
+                    description
+                    projectName
+                    fields {
+                        name
+                    }
+                }
+            }""", {"name": args.datasource_name})
+
+        # Display warnings/errors (if any)
+        if result.get("errors"):
+            print("### Errors/Warnings:")
+            pprint(result["errors"])
+        
+        # Print the results
+        if result.get("data"):
+            print("### Results:")
+            pprint(result["data"]["publishedDatasources"])
+
+if __name__ == '__main__':
+    main()