我不确定如何解决此问题

我不知道为什么在尝试以下操作时会出现此错误runserver：

Performing system checks...

System check identified no issues (0 silenced).
Unhandled exception in thread started by <function wrapper at 0x1085589b0>
Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/django/utils/autoreload.py", line 222, in wrapper
    fn(*args, **kwargs)
  File "/Library/Python/2.7/site-packages/django/core/management/commands/runserver.py", line 107, in inner_run
    self.check_migrations()
  File "/Library/Python/2.7/site-packages/django/core/management/commands/runserver.py", line 159, in check_migrations
    executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])
  File "/Library/Python/2.7/site-packages/django/db/migrations/executor.py", line 17, in __init__
    self.loader = MigrationLoader(self.connection)
  File "/Library/Python/2.7/site-packages/django/db/migrations/loader.py", line 49, in __init__
    self.build_graph()
  File "/Library/Python/2.7/site-packages/django/db/migrations/loader.py", line 184, in build_graph
    self.applied_migrations = recorder.applied_migrations()
  File "/Library/Python/2.7/site-packages/django/db/migrations/recorder.py", line 59, in applied_migrations
    self.ensure_schema()
  File "/Library/Python/2.7/site-packages/django/db/migrations/recorder.py", line 49, in ensure_schema
    if self.Migration._meta.db_table in self.connection.introspection.get_table_list(self.connection.cursor()):
  File "/Library/Python/2.7/site-packages/django/db/backends/__init__.py", line 165, in cursor
    cursor = self.make_debug_cursor(self._cursor())
  File "/Library/Python/2.7/site-packages/django/db/backends/__init__.py", line 138, in _cursor
    self.ensure_connection()
  File "/Library/Python/2.7/site-packages/django/db/backends/__init__.py", line 133, in ensure_connection
    self.connect()
  File "/Library/Python/2.7/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Library/Python/2.7/site-packages/django/db/backends/__init__.py", line 133, in ensure_connection
    self.connect()
  File "/Library/Python/2.7/site-packages/django/db/backends/__init__.py", line 122, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/Library/Python/2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 134, in get_new_connection
    return Database.connect(**conn_params)
  File "/Library/Python/2.7/site-packages/psycopg2/__init__.py", line 164, in connect
    conn = _connect(dsn, connection_factory=connection_factory, async=async)
django.db.utils.OperationalError: could not connect to server: Connection refused
        Is the server running on host "127.0.0.1" and accepting
        TCP/IP connections on port 5432?

当我尝试连接到postgres时：

psql: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
settings.py：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'beerad',
        'USER': 'bli1',
        'PASSWORD': '',
        'HOST': '127.0.0.1',
        'PORT': '5432',
    }
}