react newforms, throw error on server response

Question

I am using react newforms for react form handling. I find it really good but couldn't figure out how to trigger an error on a given input field if the server responses with an error.

For example you got a login form and you decide not to show an alert box under the form but throw a custom error that newforms catches and displays an error message Username does not exist right below the input field. (like it does on clientside validation)

Answer 1

You can use form.addError() for this:

form.addError('username', 'Username does not exist.')

If there isn't another state change happening associated with the server response, you may need to force your component to re-render.

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It also supports async validation, so it's possible to do the server call inside a custom validation method and get the form to add the error for you (suitability depends on when the server call needs to happen).

http://newforms.readthedocs.org/en/latest/validation.html#asynchronous-validation