CODEWITHSUNDEEP
javascriptreactjsaxiosreact-hooks
Eric Christensen
Eric Christensen

Reputation: 197

React hooks 'useState()' updater function with axios.post on form submits

Here is my issue: I am using react hooks functional components with the newer useState hook. The useState hook returns an updater function used to update that state. The updater function is the issue I am having and this is common knowledge of how React works. The state isn't updated until the dom re-renders. But I need to send form data onSubmit over axios (or fetch).

const App = () => {
    const [username, setUsername] = useState('')

    const handleSubmit = (e) => {
        e.preventDefault()
        setUsername(e.target.elements.form1.value)
        axios.post('http://localhost:3000/api', { name: username })
    }

    return (
        <div>
            <form onSubmit={handleSubmit}>
                <input type="text" name="form1" placeholder="Enter name:" />
                <button type="submit">Submit</button>
            </form>
        </div >
    )
}

In this code when the form is submitted with the onSubmit event on the form tag, the handleSubmit() function is called. Here the setUsername() updater function is going to update the sate and axios runs a post call to a backend server. But the axios.post will always only send the previous state value because the setUsername() function wont finish until the dom is re rendered. So the data coming into the backend always appears one step behind.

What is the best method to do this correctly? With my form inputs I don't really need them to be rendered to the dom, I just need the form info to be passed to the backend. Should I not even put this data in the state? And if so whats the best way to do this with a large form; say 10 inputs values?

I also have seen people use value={some state value} in the input form for two way binding; but that makes using more then one input in a form very difficult using hooks. Unless there is some magical way I missed.

I have just never seen the 'standard' way of performing axios or fetch calls in react with Hooks. I have searched the web a lot but there doesn't seem to be a lot of information on it.

Upvotes: 1

Views: 3855

Answers (1)

Dupocas
Dupocas

Reputation: 21297

State's updates are asynchronous (with hooks the value will only be updated in the next render).

But you already know what value looks like cause is inside your scope already. Just pass it to axios

const App = () => {
    const [username, setUsername] = useState('')

    const handleSubmit = (e) => {
        e.preventDefault()
        const { value } = e.target.elements.form1
        setUsername(value)
        axios.post('http://localhost:3000/api', { name: value })
    }

    return (
        <div>
            <form onSubmit={handleSubmit}>
                <input type="text" name="form1" placeholder="Enter name:" />
                <button type="submit">Submit</button>
            </form>
        </div >
    )
}

Upvotes: 10

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