title: How to trigger validation in formik after rendering?
body: <p>I have one question with formik. Basically, I will have a table which list all the Id of the forms which have errors. When user click on the Id of a form, it will show up the form itself. The requirement is the errors should be showing also when the form is rendered. Does anyone know how to do that with Formik ? Also, if user edit the field the field validation should works as normal. </p>
  
  <p>I put the codesandbox link here. <a href="https://codesandbox.io/s/pensive-brattain-yyls2" rel="noreferrer">https://codesandbox.io/s/pensive-brattain-yyls2</a>. Basically I want that when the form show up I should see the errors, not just when user move away from the field or changing it. Thank you.</p>
  
  <pre><code>import { Formik, Field, Form } from "formik";
  import { TextField } from "formik-material-ui";
  
  class Post0 extends React.Component {
     validateEmptyName(value) {
        if (!value) {
          return "Invalid Name";
        }
     }
  
   render() {
    return (
    &lt;div&gt;
      &lt;Formik
        initialValues={{
          email: "",
          animal: ""
        }}
        onSubmit={values =&gt; {
          this.props.nextStep(values);
        }}
        render={({ values, isSubmitting }) =&gt; (
          &lt;Form&gt;
            &lt;Field
              name="email"
              type="email"
              value={values.email}
              component={TextField}
              variant="outlined"
              validate={this.validateEmptyName}
            /&gt;
            &lt;Field
              name="animal"
              value={values.animal}
              component={TextField}
              variant="outlined"
            /&gt;
  
            &lt;button type="submit"&gt;Submit&lt;/button&gt;
          &lt;/Form&gt;
        )}
      /&gt;
    &lt;/div&gt;
  );
  </code></pre>
  
  <p>}
  }</p>