Allow to disable the UserMenu without rewriting the AppBar

[Luwangel]

Fixes #5419

Sometimes applications are not required to have any users.
For that purpose I think it would be a great idea to pass userMenu={false} as a prop in a custom AppBar component.

Using false without a true option may be confusing. So I use null instead.

Todo

• Allow to pass null to the userMenu prop of the <AppBar>
• Update TS type for the <AppBar>

Screenshot

// examples/simple/src/Layout.js line 42
const MyAppBar = props => <AppBar {...props} userMenu={null} />;

[djhi]

Using false without a true option may be confusing. So I use null instead.

We currently use false for things like this everywhere in react-admin. I think we should keep it consistant

[Luwangel]

Using false without a true option may be confusing. So I use null instead.

We currently use false for things like this everywhere in react-admin. I think we should keep it consistant

And if we put true, should we display the default <UserMenu>?

[djhi]

And if we put true, should we display the default ?

It should not accept a boolean but either false or an element (on the TS type). If true is provided, an error should probably be thrown. I'll try to find an example somewhere

[djhi]

See https://github.com/marmelab/react-admin/blob/master/packages/ra-ui-materialui/src/list/ListView.tsx#L72 (bulkActionsButtons) for example. Not saying I love the pattern btw 😛

[fzaninotto]

The default value is undefined, using null as something different will confuse users IMHO. So I'd prefer false, even though it sucks for TS stypes.

[djhi]

Suggested change

	userMenu?: JSX.Element | boolean;
	userMenu?: JSX.Element | false;

[djhi]

I think this should work

[Luwangel]

True is allowed because it will display the default user menu.