Rails/React App Signup throwing 500 internal server error - reactjs

Question

I'm trying to get user data to save to my Rails DB for user info through a sign up form on a React front end. I've got my route and controller written properly (at least I think) and the fetch request below but I keep getting a 500 internal error through on submit. Please let me know what I'm missing, any help would be greatly appreciated!
My route:
resources :users, only: [:show, :create]
My create action in UsersController:
def create
user = User.create!(user_params)
if user.valid?
session[:user_id] = user.id # remembering who our user is
render json: user, status: :ok
else
render json: {error: user.errors.messages}
end
end
and lastly my fetch request from the Signup.js component on the React frontend, where I'm getting the error on the line that has 'fetch'
fetch(`/users`,{
method:'POST',
headers:{'Content-Type': 'application/json'},
body:JSON.stringify(user)
})
.then(res => {
if(res.ok){
res.json().then(user => {
history.push(`/users/${user.id}`)
})

Answer 1

This might only be part of your problem, but first creating, then asking for validity is backwards.
Do something like this instead:
def create
user = User.new(user_params)
if user.save # <-- will return false if the save fails
user.reload
session[:user_id] = user.id # remembering who our user is
render json: user, status: :ok
else
render json: {error: user.errors.messages}
end
end
If you really want to check validity explicitly:
def create
user = User.new(user_params)
if user.valid? # <-- will check validity
user.save
user.reload
session[:user_id] = user.id # remembering who our user is
render json: user, status: :ok
else
render json: {error: user.errors.messages}
end
end
My guess is your error might be coming from the fact that your user variable doesn't actually have an ID yet. You need to save the record, then refresh it to get an ID.