How to properly use useField hook from Formik in typescript

Question

I followed everything from documentation and watched the tutorial by Ben Awad on YouTube. And still, I cannot get it to work.

const TextField = (props: FieldHookConfig<{}>) => {
    const [field] = useField(props);
        return (
            <div>
                <input {...field} {...props}/>
            </div>
        );
    };

I used the FieldHookConfig as the type for the props because the useField is expecting a string or the FieldHookConfig base on the Field.d.ts file. yet typescript is still not happy.

it complains right in this line <input {...field} {...props}/>

(property) JSX.IntrinsicElements.input: React.DetailedHTMLProps<React.InputHTMLAttributes<HTMLInputElement>, HTMLInputElement>
Type '{ ref?: string | ((instance: HTMLInputElement | null) => void) | RefObject<HTMLInputElement> | null | undefined; key?: string | number | undefined; ... 289 more ...; innerRef?: ((instance: any) => void) | undefined; } | { ...; } | { ...; }' is not assignable to type 'DetailedHTMLProps<InputHTMLAttributes<HTMLInputElement>, HTMLInputElement>'.
  Type '{ ref?: string | ((instance: HTMLSelectElement | null) => void) | RefObject<HTMLSelectElement> | null | undefined; key?: string | number | undefined; ... 269 more ...; checked?: boolean | undefined; }' is not assignable to type 'DetailedHTMLProps<InputHTMLAttributes<HTMLInputElement>, HTMLInputElement>'.
    Type '{ ref?: string | ((instance: HTMLSelectElement | null) => void) | RefObject<HTMLSelectElement> | null | undefined; key?: string | number | undefined; ... 269 more ...; checked?: boolean | undefined; }' is not assignable to type 'ClassAttributes<HTMLInputElement>'.
      Types of property 'ref' are incompatible.
        Type 'string | ((instance: HTMLSelectElement | null) => void) | RefObject<HTMLSelectElement> | null | undefined' is not assignable to type 'string | ((instance: HTMLInputElement | null) => void) | RefObject<HTMLInputElement> | null | undefined'.
          Type '(instance: HTMLSelectElement | null) => void' is not assignable to type 'string | ((instance: HTMLInputElement | null) => void) | RefObject<HTMLInputElement> | null | undefined'.
            Type '(instance: HTMLSelectElement | null) => void' is not assignable to type '(instance: HTMLInputElement | null) => void'.
              Types of parameters 'instance' and 'instance' are incompatible.
                Type 'HTMLInputElement | null' is not assignable to type 'HTMLSelectElement | null'.
                  Type 'HTMLInputElement' is missing the following properties from type 'HTMLSelectElement': length, options, selectedIndex, selectedOptions, and 4 more.ts(2322)

Answer 1

There are 2 problems, firstly, you cannot spread the props variable on the <input> element, due to the incompatible types (as specified in the error). Secondly, your generic type for FieldHookConfig shouldn't be {}, rather it should be string

So to fix it, suppose you are using your <TextField> element like so

<TextField
  name="firstName"
  type="text"
  placeholder="Jane"
/>

Then inside your TextField definition, you will write

const TextField = (props: FieldHookConfig<string>) => {
  const [field] = useField(props);
  return (
    <div>
      {/* no need to pass the name field because Formik will accept
      that prop internally and pass it to the field variable */}
      <input {...field} placeholder={props.placeholder} type={props.type} />
    </div>
    );
};