React-admin: How to pass logged in user ID to API backend - reactjs

Question

I am using React-admin to make an application to manage articles and have many people logged in to write articles
I want to pass the USER_ID who is logged in to React-admin to CREATED_BY of API backend when posting a Article
Here is the code example for the add a Post function
export const PostCreate = (props) => {
return (
<Create {...props}>
<PostForm></PostForm>
</Create>)
};
const PostForm = (props ) => (
<FormWithRedirect
{...props}
render={(formProps) => (
// here starts the custom form layout
<form>
<Box p="1em">
<Box display="flex">
<Box flex={2} mr="1em">
<Typography variant="h6" gutterBottom>
Offer
</Typography>
<Box display="flex">
<TextInput source="title" fullWidth />
</Box>
<TextInput source="slug" fullWidth />
<ImageInput
source="pictures"
label="Related pictures"
accept="image/*"
fullWidth
>
<ImageField source="image" title="title" />
</ImageInput>
<TextInput multiline source="description" fullWidth />
<MarkdownInput source="content" fullWidth></MarkdownInput>
<Box mt="1em" />
<Typography variant="h6" gutterBottom>
Address
</Typography>
<Box display="flex">
<Box flex={1} mr="0.5em">
<BooleanInput label="Featured" source="featured" />
</Box>
<Box flex={1} mr="0.5em">
<BooleanInput label="Publish" source="published" />
</Box>
</Box>
</Box>
</Box>
</Box>
<Toolbar>
<Box display="flex" justifyContent="space-between" width="100%">
<SaveButton
saving={formProps.saving}
handleSubmitWithRedirect={formProps.handleSubmitWithRedirect}
redirect={
redirectEdit ? redirectEdit : `/posts/${formProps.record.id}`
}
/>
<DeleteButton
record={formProps.record}
redirect={`/posts/`}
/>
</Box>
</Toolbar>
</form>
)}
/>
)
I tried to get UserId from useGetIdentity
import { useGetIdentity } from "react-admin";
but don't know how to pass the value in
export const PostCreate = (props) => {
const { identity } = useGetIdentity();
return (
<Create {...props}>
<PostForm defaultValue={{ user_id: identity }}></PostForm>
</Create>)
};