title: Change input value through click on button
body: <p>I currently struggle with the button "Auto generate link". Once clicked, the Field "link" should be filled with the data "<a href="http://predefinedlink.com" rel="nofollow noreferrer">http://predefinedlink.com</a>"</p>
  
  <p>Due to the combination of Formik + Material UI used here, I struggle to achieve that.</p>
  
  <pre><code>const useStyles = makeStyles((theme) =&gt; ({[...]}));
  
  const EventStream = ({ onSubmit, eventStream }) =&gt; {
    const classes = useStyles();
  
    return (
      &lt;Formik
        initialValues={{
          link: maybe(() =&gt; eventStream.link, "") || "",
        }}
        onSubmit={onSubmit}
        validateOnBlur={false}
        validateOnChange={false}
        enableReinitialize
      &gt;
        {({ handleSubmit, isSubmitting, dirty }) =&gt; (
          &lt;FormikForm autoComplete="off" noValidate&gt;
            &lt;Card&gt;
              &lt;CardContent&gt;
                &lt;Grid container spacing={3}&gt;
                  &lt;Grid xs={12} item&gt;
                    &lt;Field name="link" label="Link" component={TextField} /&gt;
                    &lt;button
                      onClick={console.log("Fill TextField 'link' with new data")}
                    &gt;
                      Auto generate link &amp;raquo;
                    &lt;/button&gt;
                  &lt;/Grid&gt;
                &lt;/Grid&gt;
              &lt;/CardContent&gt;
              &lt;CardActions className={classes.cardActions}&gt;
                &lt;Button
                  variant="contained"
                  color="primary"
                  classes={{
                    root: clsx(classes.saveButton, {
                      [classes.saveButtonDirty]: !dirty,
                    }),
                    disabled: isSubmitting &amp;&amp; classes.saveButtonDisabled,
                  }}
                  disabled={isSubmitting || !dirty}
                  onClick={handleSubmit}
                &gt;
                  Save
                  {isSubmitting &amp;&amp; (
                    &lt;CircularProgress
                      size={20}
                      thickness={5}
                      color="inherit"
                      className={classes.saveButtonProgress}
                    /&gt;
                  )}
                &lt;/Button&gt;
              &lt;/CardActions&gt;
            &lt;/Card&gt;
          &lt;/FormikForm&gt;
        )}
      &lt;/Formik&gt;
    );
  };
  
  export default EventStream;
  </code></pre>