Q:

Material-UI Select e.target.value is undefined

I'm using Material-UI's Select component in one of my React projects. I require the dropdown data to be shown in groups, hence I'm using <MenuItem> wrapped around <ListSubheader>. I'm having a hard time getting the value of my MenuItems. Please let me know if there's anything blatantly wrong with my code.
<FormControl>
    <InputLabel>Product type</InputLabel>
    <Select
    id="product-type"
    input={<Input id="grouped-select" />}
    value={this.state.productType}
    autoWidth={true}
    style={{ width: 200 }}
    onChange={(e, child) => {
        console.log(e.target.value); // undefined!
    }}
    >
    {this.state.productList.map((p, i) => {
        const list = p[1];

        let items = list.map((e, j) => {
        return (
            <MenuItem key={j} value={e.name}>
            {e.name}
            </MenuItem>
        );
        });

        return (
        <div>
            <ListSubheader key={i}>{p[0]}</ListSubheader>
            {items}
        </div>
        );
    })}
    </Select>
</FormControl>

A:

The reason e.target.value was returning undefined was, as others mentioned, due to the fact that MenuItem wasn't a direct child of Select. Since productList is dynamically being set into the dropdown, it has to be rendered in such a way:
ListSubheader0
   Item0
   Item1
ListSubheader1
   Item2
   Item3
   Item4
   ...
...

Instead of wrapping my ListSubheader and MenuItem in a div tag where reading the target.value was impossible, I returned an array.
return [
    <ListSubheader key={i}>
        {p[0]}
    </ListSubheader>, 
    items
];

