React passing state to children with Navbar - reactjs

Question

I have a simple react Navbar from bootstrap and I want to pass a userid from the navbar to a child.
I can do that working but when so, the child component is shown twice, once above the navbar and the second time below.
This happens only when I insert this command:
<UserConfig userid={this.state.user.userid} />
Here is a part of my App.js with the navigation
I tried many places to paste it in, but nothing worked
render() {
console.log(this.state.user.userid);
return (
<div className="App container" >
<UserConfig userid={this.state.user.userid} />
<Navbar fluid collapseOnSelect>
<Navbar.Header>
<Navbar.Brand>
<Link to="/">Hallo {jwt_decode(authentication.getAccessToken()).given_name}!</Link>
</Navbar.Brand>
<Navbar.Toggle />
</Navbar.Header>
<Navbar.Collapse>
<Nav pullRight>
<LinkContainer to="/config">
<NavItem >Konfiguration</NavItem>
</LinkContainer>
<LinkContainer to="/logout">
<NavItem>Logout</NavItem>
</LinkContainer>
<LinkContainer to="/callback">
<NavItem>Callback</NavItem>
</LinkContainer>
</Nav>
</Navbar.Collapse>
</Navbar>
<Routes />
</div>
);
}
In my UserConfig.js I just use this.props.userid which shows the value only when the navbar is crashed.....
Could you please help me to get that working?
Actually I just want to pass down the userid from App.js to UserConfig.js WITHOUT destroying my navigation.
UserConfig
render() {
console.log(this.props.userid);
return (
<div className="Login">
<form onSubmit={this.handleSubmit}>
<FormGroup controlId="hersteller" >
<ControlLabel >Hersteller</ControlLabel>
<FormControl
autoFocus
type="text"
value={this.state.hersteller}
onChange={this.handleChange}
/>
</FormGroup>
......

Answer 1

What is the correct way to pass props to NavItem
From this question... try this:
<LinkContainer to="/config">
<NavItem data-userid={this.state.userid} >Konfiguration</NavItem>
</LinkContainer>
I am assuming that is config page you are trying to get the value too? You can then remove the UserConfig component above the navigation (which should remove the double render).