Formik and Material-UI

Question

I am trying to use Formik with Material-UI text field. Like so:

import TextField from '@material-ui/core/TextField';
import {
  Field,
  FieldProps,
  Form,
  Formik,
  FormikErrors,
  FormikProps
} from 'formik';
import React, { Component } from 'react';

interface IMyFormValues {
  firstName: string;
}

class CreateAgreementForm extends Component<{}> {
  public render() {
    return (
      <div>
        <h1>My Example</h1>
        <Formik
          initialValues={{ firstName: '' }}
          // tslint:disable-next-line:jsx-no-lambda
          onSubmit={(values: IMyFormValues) => alert(JSON.stringify(values))}
          // tslint:disable-next-line:jsx-no-lambda
          validate={(values: IMyFormValues) => {
            const errors: FormikErrors<IMyFormValues> = {};
            if (!values.firstName) {
              errors.firstName = 'Required';
            }
            return errors;
          }}
          // tslint:disable-next-line:jsx-no-lambda
          render={(formikBag: FormikProps<IMyFormValues>) => (
            <Form>
              <Field
                name="firstName"
                render={({ field, form }: FieldProps<IMyFormValues>) => (
                  <TextField
                    error={Boolean(
                      form.errors.firstName && form.touched.firstName
                    )}
                    helperText={
                      form.errors.firstName &&
                      form.touched.firstName &&
                      String(form.errors.firstName)
                    }
                  />
                )}
              />
            </Form>
          )}
        />
      </div>
    );
  }
}

export default CreateAgreementForm;

I want Formik to be responsible for validation and Material-UI for looks. I want to pass errors.firstName to TextField component but the error doesn't display correctly. How can I fix it so it still will be clear to read? I don't want to write my own TextField component.

Answer 1

I don't think you need another library or even create your own wrapper, I think you need to tweek your code a bit.

One problem you have is that you don't pass an onChange function in the Material TextField so the form value of firstName is always null and so you always get the error, even if you have entered a name. Try adding a name or id on your TextField and an onChange function like so:

<Field
    validateOnBlur
    validateOnChange
    name="firstName"
    render={({ field, form }) => (
    <TextField
        name={"firstName"}
        error={
            Boolean(form.errors.firstName && form.touched.firstName)
        }
        onChange={formikBag.handleChange}
        onBlur={formikBag.handleBlur}
        helperText={
            form.errors.firstName &&
            form.touched.firstName &&
            String(form.errors.firstName)
        }
    />
    )}
/>