Passing value to hidden input from dropdown menu in react - reactjs

Question

I have react-select dropdown menu and hidden input which I pass to form when submiting...
using useState hook I created variable which tracks changes to react-select dropdown menu.
Hidden input has this variable as value also. I thought this would be enough.
But when I submit the form, console. log shows me that value of input is empty despite that variable that was selected from dropdown menu is actually updated.
I mean variable that I have chosen console logs some value, but hidden input thinks that it is still empty.
Does it means I have to rerender manually page each time I change that variable so input gets it's new value using useEffect ? Which is bad solution for me, I don't like it, thought it would be done automatically.
Or instead of useState I must create and use variable via Redux ? Which I also don't like, use redux for such small thing fills overcomplicated.
Isn't there any nice elegant solution ? :)
import { useForm } from 'react-hook-form';
const [someVar,setSomeVar]=useState('');
const {
register,
handleSubmit,
formState: { errors },
} = useForm({ mode: 'onBlur' });
const handleFormSubmit = (data) => {
console.error('success');
};
const handleErrors = (errors) => {
console.error(errors);
console.log(document.getElementsByName('hiddenInput')[0].value);
};
const options = {
hiddenInput: {
required: t('hiddenInput is required'),
},
};
.......
<form onSubmit={handleSubmit(handleFormSubmit, handleErrors)}>
<Select
options='...some options list'
onChange={(value) => setSomeVar(value)}
/>
<input
name='hiddenInput'
value={someVar}
{...register('hiddenInput', options.hiddenInput)}
/>
<button>submit</button>
</form>
UPDATED

Answer 1

Its because getElementsByName returns an array of elements.
You probably want
document.getElementsByName('hiddenInput')[0].value
I should add that really you should use a ref attached to the input and not access it via the base DOM API.
const hiddenRef = useRef(null)
// ...
cosnt handleSubmit =(e)=>{
console.log(hiddenRef.current.value);
}
// ...
<input
name='hiddenInput'
value={someVar}
ref={hiddenRef}
/>
However as you are using react-hook-form you need to be interacting with its state store so the library knows the value.
const {
register,
handleSubmit,
formState: { errors },
setValue
} = useForm({ mode: 'onBlur' });
// ...
<form onSubmit={handleSubmit(handleFormSubmit, handleErrors)}>
<Select
options='...some options list'
onChange={(value) => setValue('hiddenInput', value)}
/>
<input
name='hiddenInput'
{...register('hiddenInput', options.hiddenInput)}
/>
<button>submit</button>
</form>
You can remove const [someVar,setSomeVar]=useState('');
However, this hidden input is not really necessary as you mention in comments. You just need to bind the dropdown to react hook form.
// controller is imported from react hook form
<form onSubmit={handleSubmit(handleFormSubmit, handleErrors)}>
<Controller
control={control} // THIS IS FROM useForm return
name="yourDropdown"
rules={{required: true}}
render={({
field: { onChange, value, name, ref }
}) => (
<Select
options={options}
inputRef={ref}
value={options.find(c => c.value === value)}
onChange={val => onChange(val.value)}
/>
)}
/>
<button>submit</button>
</form>