In react-admin library, when I try to post an object via http-request with the schema in the backend (id, firstname, lastname, email) with the id is autogenerated, It shows the error message : 'Cannot read properties of undifined (reading 'id')"

this is the code of Create component:

const TeacherCreate = (props) => {
return (
<Create title="Teachers form" {...props}>
    <SimpleForm validate={validateUserCreation}>
        <TextInput source="firstname" />
        <TextInput source="lastname"/>
        <TextInput source="email" />
    </SimpleForm>
</Create>
)
}

export default TeacherCreate

How to solve it?