add wynaut-export with CSV support

setup.py

@@ -40,7 +40,8 @@ setup(
     entry_points={
         'console_scripts': [
             'isso = isso:main',
-            'wynaut-import = wynaut.imprt:main'
+            'wynaut-import = wynaut.imprt:main',
+            'wynaut-export = wynaut.export:main'
         ],
     },
 )

wynaut/export.py

@@ -0,0 +1,77 @@
+# -*- encoding: utf-8 -*-
+
+from __future__ import unicode_literals
+
+import sys
+
+from io import StringIO
+from csv import writer as csv_writer
+
+from isso.db import SQLite3
+from isso.core import Config
+from isso.compat import PY2K, text_type as str
+
+from wynaut import get_parser
+
+if PY2K:
+    _StringIO = StringIO
+    class StringIO(_StringIO):
+
+        def write(self, data):
+            data = data.decode("utf-8")
+            return super(StringIO, self).write(data)
+
+
+def csv(db, threads=True, comments=False):
+    """
+    Print threads *or* comments formatted as CSV (Excel dialect).  Rows are
+    separated by comma and `None` is replaced with the empty string.
+
+    The first line is always a row containing the identifiers per column.
+    """
+
+    fp = StringIO()
+    writer = csv_writer(fp, dialect="excel")
+
+    fmt = lambda val: "" if val is None else val
+
+    if threads:
+        writer.writerow(["id", "uri", "title"])
+        query = db.execute("SELECT id, uri, title FROM threads").fetchall()
+    else:
+        fields = ["id", "parent", "created", "modified", "mode", "remote_addr",
+                  "author", "email", "website", "likes", "dislikes", "text"]
+        writer.writerow(fields)
+        query = db.execute("SELECT %s FROM comments" % ",".join(fields))
+
+    for row in query:
+        writer.writerow(map(lambda s: str(fmt(s)).encode("utf-8"), row))
+
+    fp.seek(0)
+    for line in fp:
+        sys.stdout.write(line.encode("utf-8"))
+
+
+def main():
+
+    parser = get_parser("export to various formats")
+    parser.add_argument("-t", "--to", dest="type", choices=["csv"],
+        help="export format")
+
+    group = parser.add_mutually_exclusive_group()
+    group.add_argument("--threads", action="store_true",
+        help="export threads (only for csv)")
+    group.add_argument("--comments", action="store_true",
+        help="export comments (only for csv)")
+
+    args = parser.parse_args()
+
+    conf = Config.load(args.conf)
+    db = SQLite3(conf.get("general", "dbpath"), conf)
+
+    if args.type == "csv":
+
+        if not any((args.threads, args.comments)):
+            raise SystemExit("CSV export needs either --comments or --threads")
+
+        csv(db, args.threads, args.comments)