uncontrolled forms

lessons/06-advance-react/C-uncontrolled-forms.md

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+We are now going to do a contact page for our site. As part of that, we will accept a name, email, and message from our users and submit it our backend. Like all good backends, ours will log it to the console and then ignore it.
+
+We are going to see two new concepts here: how to do a post with TanStack Query (which they call a mutation) and how to do uncontrolled forms with React. Let's start with our API query. In src/api, create a file called postContact.js and put this in there.
+
+```javascript
+export default async function postContact(name, email, message) {
+  const response = await fetch("/api/contact", {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({ name, email, message }),
+  });
+
+  if (!response.ok) {
+    throw new Error("Network response was not ok");
+  }
+
+  return response.json();
+}
+```
+
+Create a new link to our page in index.lazy.jsx
+
+```javascript
+// after past orders
+<li>
+  <Link to="/contact">Contact</Link>
+</li>
+```
+
+Create a new route called contact.lazy.jsx in src/routes
+
+```javascript
+import { createLazyFileRoute } from "@tanstack/react-router";
+import { useMutation } from "@tanstack/react-query";
+import postContact from "../api/postContact";
+
+export const Route = createLazyFileRoute("/contact")({
+  component: ContactRoute,
+});
+
+function ContactRoute() {
+  const mutation = useMutation({
+    mutationFn: function (e) {
+      e.preventDefault();
+      const formData = new FormData(e.target);
+      return postContact(
+        formData.get("name"),
+        formData.get("email"),
+        formData.get("message")
+      );
+    },
+  });
+
+  return (
+    <div className="contact">
+      <h2>Contact</h2>
+      {mutation.isSuccess ? (
+        <h3>Submitted!</h3>
+      ) : (
+        <form onSubmit={mutation.mutate}>
+          <input name="name" placeholder="Name" />
+          <input type="email" name="email" placeholder="Email" />
+          <textarea placeholder="Message" name="message"></textarea>
+          <button>Submit</button>
+        </form>
+      )}
+    </div>
+  );
+}
+```
+
+- We are using a mutation from TanStack React Query. Much it works very similar to normal gets except this one sends information to the API instead of gets it.
+- Notice we're using `isSuccess` to show or hide the form. Once the mutation has successfully been submitted, we just want to show them that and then hide the form.
+- Notice we're not using state or useState at all here. We're using an "uncontrolled" form which just means we're letting the DOM manage the state. Only on a submit event are we reading from the DOM using the FormData API. We use that to submit to our API the contact data.
+- There's also isError and isIdle, we just didn't use them from TanStack Query
+- Also notice in the dev tools for TanStack Query the mutations (it's in another tab.)
+
+Try it! You'll notice in the logs of where-ever your API is running that it logs out the contact info.
+
+> 🏁 [Click here to see the state of the project up until now: 13-uncontrolled-forms][step]
+
+[step]: https://github.com/btholt/citr-v9-project/tree/master/13-uncontrolled-forms