diff options
| -rw-r--r-- | doc/build/changelog/unreleased_13/4392.rst | 7 | ||||
| -rw-r--r-- | lib/sqlalchemy/dialects/postgresql/psycopg2.py | 31 | ||||
| -rw-r--r-- | test/dialect/postgresql/test_dialect.py | 19 |
3 files changed, 57 insertions, 0 deletions
diff --git a/doc/build/changelog/unreleased_13/4392.rst b/doc/build/changelog/unreleased_13/4392.rst new file mode 100644 index 000000000..ecb10ca25 --- /dev/null +++ b/doc/build/changelog/unreleased_13/4392.rst @@ -0,0 +1,7 @@ +.. change:: + :tags: engine, postgresql, usecase + :tickets: 4392 + + A :class:`.URL` connection now supports multiple hosts for PostgreSQL. Any + query that contains multiple hosts will now group the hosts as a string + instead of a tuple of strings. Pull request courtesy Ramon Williams. diff --git a/lib/sqlalchemy/dialects/postgresql/psycopg2.py b/lib/sqlalchemy/dialects/postgresql/psycopg2.py index 91576c4d2..3c9ef72c4 100644 --- a/lib/sqlalchemy/dialects/postgresql/psycopg2.py +++ b/lib/sqlalchemy/dialects/postgresql/psycopg2.py @@ -71,6 +71,28 @@ using ``host`` as an additional keyword argument:: `PQconnectdbParams \ <http://www.postgresql.org/docs/9.1/static/libpq-connect.html#LIBPQ-PQCONNECTDBPARAMS>`_ +Multiple Hosts in Connection String +------------------------ +psycopg2 supports multiple connection points in the connection string. +When the ``host`` parameter is used multiple times in the query section of +the URL, SQLAlchemy will create a single string of the host and port +information provided to make the connections:: + + create_engine( + "postgresql+psycopg2://user:password@/dbname?host=HostA:port1&host=HostB&host=HostC" + ) + +A connection to each host is then attempted until either a connection is successful +or all connections are unsuccessful in which case an error is raised. + +.. versionadded:: 1.3.20 Support for multiple hosts in PostgreSQL connection + string. + +.. seealso:: + + `PQConnString \ + <https://www.postgresql.org/docs/10/libpq-connect.html#LIBPQ-CONNSTRING>`_ + Empty DSN Connections / Environment Variable Connections --------------------------------------------------------- @@ -929,16 +951,25 @@ class PGDialect_psycopg2(PGDialect): def create_connect_args(self, url): opts = url.translate_connect_args(username="user") + + is_multihost = False + if "host" in url.query: + is_multihost = isinstance(url.query["host"], (list, tuple)) + if opts: if "port" in opts: opts["port"] = int(opts["port"]) opts.update(url.query) + if is_multihost: + opts["host"] = ",".join(url.query["host"]) # send individual dbname, user, password, host, port # parameters to psycopg2.connect() return ([], opts) elif url.query: # any other connection arguments, pass directly opts.update(url.query) + if is_multihost: + opts["host"] = ",".join(url.query["host"]) return ([], opts) else: # no connection arguments whatsoever; psycopg2.connect() diff --git a/test/dialect/postgresql/test_dialect.py b/test/dialect/postgresql/test_dialect.py index 43c5aea21..8ee5a6e2f 100644 --- a/test/dialect/postgresql/test_dialect.py +++ b/test/dialect/postgresql/test_dialect.py @@ -159,6 +159,25 @@ class DialectTest(fixtures.TestBase): eq_(cargs, []) eq_(cparams, {"host": "somehost", "any_random_thing": "yes"}) + def test_psycopg2_nonempty_connection_string_w_query_two(self): + dialect = psycopg2_dialect.dialect() + url_string = "postgresql://USER:PASS@/DB?host=hostA" + u = url.make_url(url_string) + cargs, cparams = dialect.create_connect_args(u) + eq_(cargs, []) + eq_(cparams["host"], "hostA") + + def test_psycopg2_nonempty_connection_string_w_query_three(self): + dialect = psycopg2_dialect.dialect() + url_string = ( + "postgresql://USER:PASS@/DB" + "?host=hostA:portA&host=hostB&host=hostC" + ) + u = url.make_url(url_string) + cargs, cparams = dialect.create_connect_args(u) + eq_(cargs, []) + eq_(cparams["host"], "hostA:portA,hostB,hostC") + class ExecuteManyMode(object): __only_on__ = "postgresql+psycopg2" |