Warning: Each child in a list should have a unique "key" prop;

[AndriiPetrashchukEmpeek]

I got the error "Warning: Each child in a list should have a unique "key" prop;"
when I used the "SimpleList" component;

Example
<SimpleList
primaryText={record => record.email}
secondaryText={record => record.roleId}
tertiaryText={record => (record.isActive ? 'Active' : 'Inactive')}
linkType="edit"
/>

Environment

• React-admin version: ^3.12.2
• React version: ^17.0.1
• Browser: Google Chrome

[djhi]

Thanks for reporting this. Please provide a sample application showing the issue by forking the following CodeSandbox (https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple).

[fzaninotto]

I confirm that I can't reproduce the problem with the simple example (where PostList renders a SimpleList on small screens). Could it be that some of the records in your list share the same id?

[fzaninotto]

I managed to reproduce the problem by slowing down the dataProvider. The problem lies in the SimpleListLoading component.

[aenonGit]

what if the items do not have ids? This is my case and I get the same error in console

[slax57]

@aenonGit As stated in the docs:

React-admin requires that each resource has an id field to identify it. If your API uses a different name for the primary key, you have to map that name to id in your dataProvider.