Issue in validation in react autocomplete in multiple select using formik - reactjs

Question

I am trying to validate the autocomplete multiple select using the formik. First time it is working on button click but when I remove the selected value then it is not validation.
import React from "react";
import ReactDOM from "react-dom";
import { Formik, Form } from "formik";
import TextField from "#material-ui/core/TextField";
import Autocomplete from "#material-ui/lab/Autocomplete";
import Button from "#material-ui/core/Button";
import * as Yup from 'yup';
const cities = [{
state: "Illinois",
name: "Chicago",
id: 3,
}, {
state: "Texas",
name: "Houston",
id: 2
}, {
state: "California",
name: "Los Angeles",
id: 1
}, {
state: "New York",
name: "New York City",
id: 4
}];
const initialValues = {
city_id: '',
};
const submit = values => {
let city=JSON.parse(values.city_id);
};
const SignupForm = () => {
return (
<Formik initialValues={initialValues}
validationSchema = {
Yup.object().shape({
city_id: Yup.string().max(255).required('City is required')
})
}
onSubmit={submit}>
{({ handleChange,touched,errors, values, setFieldValue }) => (
<Form>
<Autocomplete
multiple
id="city_id"
name="city_id"
options={cities}
getOptionLabel={option => option.name}
style={{ width: 300 }}
onChange={(e, value) => {
console.log(value);
let val=JSON.stringify(value);
setFieldValue(
"city_id",
value !== null ? val : initialValues.city_id
);
}}
renderInput={params => (
<TextField
error={Boolean(touched.city_id && errors.city_id)}
helperText={touched.city_id && errors.city_id}
margin="normal"
label="Cities"
fullWidth
name="city_id"
{...params}
/>
)}
/>
<Button variant="contained" color="primary" type="submit">
Submit
</Button>
</Form>
)}
</Formik>
);
}
export default SignupForm;
Please provide better validation option if I have made mistake.

Answer 1

Validation will not run because value is never empty.
If you want to run validation, do:
setFieldValue(
"city_id",
value
);
above code will trigger validation because value will be "" when you remove.