docs: updated README

Author: trbtm

README.md

@@ -16,7 +16,7 @@ pip install casbin-postgresql-watcher
 ```
 
 ## Basic Usage Example
-### With Flask-authz
+
 ```python
 from flask_authz import CasbinEnforcer
 from postgresql_watcher import PostgresqlWatcher
@@ -25,23 +25,51 @@ from casbin.persist.adapters import FileAdapter
 
 casbin_enforcer = CasbinEnforcer(app, adapter)
 watcher = PostgresqlWatcher(host=HOST, port=PORT, user=USER, password=PASSWORD, dbname=DBNAME)
-watcher.set_update_callback(casbin_enforcer.e.load_policy)
+watcher.set_update_callback(casbin_enforcer.adapter.load_policy)
 casbin_enforcer.set_watcher(watcher)
-```
 
-## Basic Usage Example With SSL Enabled
+# Call should_reload before every call of enforce to make sure
+# the policy is update to date
+watcher.should_reload()
+if casbin_enforcer.enforce("alice", "data1", "read"):
+    # permit alice to read data1
+    pass
+else:
+    # deny the request, show an error
+    pass
+```
 
-See [PostgresQL documentation](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWORDS) for full details of SSL parameters.
+alternatively, if you need more control
 
-### With Flask-authz
 ```python
 from flask_authz import CasbinEnforcer
 from postgresql_watcher import PostgresqlWatcher
 from flask import Flask
 from casbin.persist.adapters import FileAdapter
 
 casbin_enforcer = CasbinEnforcer(app, adapter)
-watcher = PostgresqlWatcher(host=HOST, port=PORT, user=USER, password=PASSWORD, dbname=DBNAME, sslmode="verify_full", sslcert=SSLCERT, sslrootcert=SSLROOTCERT, sslkey=SSLKEY)
-watcher.set_update_callback(casbin_enforcer.e.load_policy)
+watcher = PostgresqlWatcher(host=HOST, port=PORT, user=USER, password=PASSWORD, dbname=DBNAME)
 casbin_enforcer.set_watcher(watcher)
+
+# Call should_reload before every call of enforce to make sure
+# the policy is update to date
+if watcher.should_reload():
+    adapter.load_policy()
+
+if casbin_enforcer.enforce("alice", "data1", "read"):
+    # permit alice to read data1
+    pass
+else:
+    # deny the request, show an error
+    pass
+```
+
+## Basic Usage Example With SSL Enabled
+
+See [PostgresQL documentation](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWORDS) for full details of SSL parameters.
+
+```python
+...
+watcher = PostgresqlWatcher(host=HOST, port=PORT, user=USER, password=PASSWORD, dbname=DBNAME, sslmode="verify_full", sslcert=SSLCERT, sslrootcert=SSLROOTCERT, sslkey=SSLKEY)
+...
 ```