Add cookbook: Working with passwords (#783)

docs/cookbook/working_with_passwords.md

@@ -0,0 +1,48 @@
+It's a comment use-case that you have a model
+with a `Password` field which needs a custom behaviour.
+
+Let's say you have the following `User` model:
+
+```py
+class User(Base):
+    __tablename__ = "user"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str] = mapped_column(String(50))
+    hashed_password: Mapped[str] = mapped_column(String)
+```
+
+In this specific case we want the following features to be available in the Admin console:
+
+- We only want `hashed_password` when creating a new `User`, and we want to hide it when editing a `User`.
+- When a User is created, the password should be hashed and stored in the `hashed_password` column.
+
+So we define the following `UserAdmin` class for it:
+
+```py
+class UserAdmin(ModelView, model=User):
+    column_labels = {"hashed_password": "password"}
+    form_create_rules = ["name", "hashed_password"]
+    form_edit_rules = ["name"]
+
+    async def on_model_change(self, data, model, is_created, request) -> None:
+        if is_created:
+            # Hash the password before saving into DB !
+            data["hashed_password"] = data["hashed_password"] +  "_hashed"
+
+```
+
+So let's see what is happening.
+
+The `column_labels` is just saying to rename `hashed_password` to `password` when displaying or creating a form for the `User`.
+
+Next we have defined two extra attributes called `form_create_rules` and `form_edit_rules` which
+controls how the create and edit forms are created.
+
+In the `form_create_rules` declaration we specify we want `name` and `hashed_password` when creating a `User`.
+
+But in `form_edit_rules` we specifically excluded `hashed_password` so we only want to edit `name` of the `User`.
+
+And finally the last step is to hash the password before saving into the database.
+There could be a few options to do this, but in this case we are overriding `on_model_change` and only hashing the password
+when we are creating a `User`.

mkdocs.yml

@@ -27,6 +27,7 @@ nav:
       - Using a request object: "cookbook/using_request_object.md"
       - Multiple databases: "cookbook/multiple_databases.md"
       - Using rich text editor: "cookbook/using_wysiwyg.md"
+      - Working with Passwords: "cookbook/working_with_passwords.md"
   - API Reference:
       - Application: "api_reference/application.md"
       - ModelView: "api_reference/model_view.md"