Add exist_ok argument to add_feed().

CHANGES.rst

@@ -40,6 +40,8 @@ Unreleased
 
 * Add the ``missing_ok`` argument to :meth:`~Reader.delete_feed`
   and :meth:`~Reader.delete_entry`.
+* Add the ``exist_ok`` argument to :meth:`~Reader.add_feed`.
+
 * In the web application, show maxrss when debug is enabled. (:issue:`269`)
 * In the web application, decrease memory usage of the entries page
   when there are a lot of entries

docs/tutorial.rst

@@ -35,17 +35,14 @@ Adding and updating feeds
 
 Create a ``podcast.py`` file::
 
-    from reader import make_reader, FeedExistsError
+    from reader import make_reader
 
     feed_url = "http://www.hellointernet.fm/podcast?format=rss"
 
     reader = make_reader("db.sqlite")
 
     def add_and_update_feed():
-        try:
-            reader.add_feed(feed_url)
-        except FeedExistsError:
-            pass
+        reader.add_feed(feed_url, exist_ok=True)
         reader.update_feeds()
 
     add_and_update_feed()

examples/podcast.py

@@ -12,7 +12,7 @@
 
 import requests
 
-from reader import make_reader, FeedExistsError
+from reader import make_reader
 
 
 feed_url = "http://www.hellointernet.fm/podcast?format=rss"
@@ -22,10 +22,7 @@
 
 
 def add_and_update_feed():
-    try:
-        reader.add_feed(feed_url)
-    except FeedExistsError:
-        pass
+    reader.add_feed(feed_url, exist_ok=True)
     reader.update_feeds()
 
 

src/reader/core.py

@@ -43,6 +43,7 @@
 from ._utils import MapType
 from ._utils import zero_or_one
 from .exceptions import EntryNotFoundError
+from .exceptions import FeedExistsError
 from .exceptions import FeedMetadataNotFoundError
 from .exceptions import FeedNotFoundError
 from .exceptions import InvalidPluginError
@@ -408,7 +409,13 @@ def close(self) -> None:
         """
         self._storage.close()
 
-    def add_feed(self, feed: FeedInput, *, allow_invalid_url: bool = False) -> None:
+    def add_feed(
+        self,
+        feed: FeedInput,
+        exist_ok: bool = False,
+        *,
+        allow_invalid_url: bool = False,
+    ) -> None:
         """Add a new feed.
 
         Feed updates are enabled by default.
@@ -419,9 +426,12 @@ def add_feed(self, feed: FeedInput, *, allow_invalid_url: bool = False) -> None:
                 Add feed even if the current Reader configuration
                 does not know how to handle the feed URL
                 (and updates for it would fail).
+            exist_ok (bool):
+                If true, don't raise :exc:`FeedExistsError`
+                if the feed already exists.
 
         Raises:
-            FeedExistsError
+            FeedExistsError: If the feed already exists, and `exist_ok` is false.
             StorageError
             InvalidFeedURLError: If ``feed`` is invalid and ``allow_invalid_url`` is false.
 
@@ -433,18 +443,28 @@ def add_feed(self, feed: FeedInput, *, allow_invalid_url: bool = False) -> None:
             To get the previous behavior (no validation),
             use ``allow_invalid_url=True``.
 
+        .. versionadded:: 2.8
+            The ``exist_ok`` argument.
+
         """
         url = _feed_argument(feed)
         if not allow_invalid_url:
             self._parser.validate_url(url)
         now = self._now()
-        self._storage.add_feed(url, now)
+        try:
+            self._storage.add_feed(url, now)
+        except FeedExistsError:
+            if not exist_ok:
+                raise
 
     def delete_feed(self, feed: FeedInput, missing_ok: bool = False) -> None:
         """Delete a feed and all of its entries, metadata, and tags.
 
         Args:
             feed (str or Feed): The feed URL.
+            missing_ok (bool):
+                If true, don't raise :exc:`FeedNotFoundError`
+                if the feed does not exist.
 
         Raises:
             FeedNotFoundError: If the feed does not exist, and `missing_ok` is false.
@@ -1526,6 +1546,9 @@ def delete_entry(self, entry: EntryInput, missing_ok: bool = False) -> None:
 
         Args:
             entry (tuple(str, str) or Entry): (feed URL, entry id) tuple.
+            missing_ok (bool):
+                If true, don't raise :exc:`EntryNotFoundError`
+                if the entry does not exist.
 
         Raises:
             EntryNotFoundError: If the entry does not exist, and `missing_ok` is false.
@@ -2094,6 +2117,9 @@ def delete_tag(
         Args:
             resource (str or Feed): The resource.
             key (str): The key of the tag to delete.
+            missing_ok (bool):
+                If true, don't raise :exc:`TagNotFoundError`
+                if the tag does not exist.
 
         Raises:
             TagNotFoundError: If the tag does not exist, and `missing_ok` is false.

tests/test_reader.py

@@ -1542,6 +1542,9 @@ def test_add_remove_get_feeds(reader, feed_arg):
     assert excinfo.value.url == one.url
     assert 'feed exists' in excinfo.value.message
 
+    # no exception
+    reader.add_feed(feed_arg(one), True)
+
     reader._now = lambda: naive_datetime(2010, 1, 2)
     reader.update_feeds()