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Adding Sign Up

Adding the Sign-Up feature

Now we will update our static SignUp.tsx to become dynamic and add the capability of submitting a user for sign up. The first step is to add state to store the new user and an error message:

We'll add a type to the types.ts file

export type NewUserType = {
fullName: string
email: string
password: string
const [errorMessage, setErrorMessage] = useState('')
const [newUser, setNewUser] = useState<NewUserType>({
fullName: '',
email: '',
password: '',

We can add a <p> tag to show the error message:

errorMessage ? <p>{errorMessage}</p> : null

then add useHistory so we can redirect the user after signing up:

const history = useHistory()

Define handlers for the fields

then we will add a function to handle the user's input in the fields:

function handleStringFieldChange(event) {
const value =
const fieldName =
const updatedUser = { ...newUser, [fieldName]: value }

Now use our two handling functions for the various <input> fields and the <form>

Update each <input> field to use this function as the onChange and add a value property to equal the appropriate attribute from newUser


Add a function to submit the new user:

async function submitNewUser(newUser: NewUserType) {
const response = await fetch('/api/Users', {
method: 'POST',
headers: { 'content-type': 'application/json' },
body: JSON.stringify(newUser),
if (response.ok) {
return response.json()
} else {
throw await response.json()

Define a mutation for creating the new user:

const createUserMutation = useMutation(
(newUser: NewUserType) => submitNewUser(newUser),
onSuccess: function () {
onError: function (error: APIError) {
setErrorMessage(Object.values(error.errors).join('. '))

Submit the form

Change the <form> element to use our new mutation:

onSubmit={(event) => {

We will also add a route in App.tsx

<Route path="/signup">
<SignUp />

And we will also add a button to our main navigation.

<Link to="/signup">Sign Up</Link>

And with this, we have the ability for users to sign up for our app!

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