Guides

Data mutation

This guide provides practical examples of using actions to mutate data in SolidStart.

Handling form submission

To handle <form> submissions with an action:

Ensure the action has a unique name. See the Action API reference for more information.
Pass the action to the <form> element using the action prop.
Ensure the <form> element uses the post method for submission.
Use the FormData object in the action to extract field data using the navite FormData methods.

import { action } from "@solidjs/router";

const addPost = action(async (formData: FormData) => {
  const title = formData.get("title") as string;
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

import { action } from "@solidjs/router";

const addPost = action(async (formData) => {
  const title = formData.get("title");
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

Passing additional arguments

To pass additional arguments to your action, use the with method:

import { action } from "@solidjs/router";

const addPost = action(async (userId: number, formData: FormData) => {
  const title = formData.get("title") as string;
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ userId, title }),
  });
}, "addPost");

export default function Page() {
  const userId = 1;
  return (
    <form action={addPost.with(userId)} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

import { action } from "@solidjs/router";

const addPost = action(async (userId, formData) => {
  const title = formData.get("title");
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ userId, title }),
  });
}, "addPost");

export default function Page() {
  const userId = 1;
  return (
    <form action={addPost.with(userId)} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

Showing pending UI

To display a pending UI during action execution:

Import useSubmission from @solidjs/router.
Call useSubmission with your action, and use the returned pending property to display pending UI.

import { action, useSubmission } from "@solidjs/router";

const addPost = action(async (formData: FormData) => {
  const title = formData.get("title") as string;
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const submission = useSubmission(addPost);
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button disabled={submission.pending}>
        {submission.pending ? "Adding..." : "Add Post"}
      </button>
    </form>
  );
}

import { action, useSubmission } from "@solidjs/router";

const addPost = action(async (formData) => {
  const title = formData.get("title");
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const submission = useSubmission(addPost);
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button disabled={submission.pending}>
        {submission.pending ? "Adding..." : "Add Post"}
      </button>
    </form>
  );
}

Handling errors

To handle errors that occur within an action:

Import useSubmission from @solidjs/router.
Call useSubmission with your action, and use the returned error property to handle the error.

import { Show } from "solid-js";
import { action, useSubmission } from "@solidjs/router";

const addPost = action(async (formData: FormData) => {
  const title = formData.get("title") as string;
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const submission = useSubmission(addPost);
  return (
    <form action={addPost} method="post">
      <Show when={submission.error}>
        <p>{submission.error.message}</p>
      </Show>
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

import { Show } from "solid-js";
import { action, useSubmission } from "@solidjs/router";

const addPost = action(async (formData) => {
  const title = formData.get("title");
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const submission = useSubmission(addPost);
  return (
    <form action={addPost} method="post">
      <Show when={submission.error}>
        <p>{submission.error.message}</p>
      </Show>
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

Validating form fields

To validate form fields in an action:

Add validation logic in your action and return validation errors if the data is invalid.
Import useSubmission from @solidjs/router.
Call useSubmission with your action, and use the returned result property to handle the errors.

import { Show } from "solid-js";
import { action, useSubmission } from "@solidjs/router";

const addPost = action(async (formData: FormData) => {
  const title = formData.get("title") as string;
  if (!title || title.length < 2) {
    return {
      error: "Title must be at least 2 characters",
    };
  }
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const submission = useSubmission(addPost);
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <Show when={submission.result?.error}>
        <p>{submission.result?.error}</p>
      </Show>
      <button>Add Post</button>
    </form>
  );
}

import { Show } from "solid-js";
import { action, useSubmission } from "@solidjs/router";

const addPost = action(async (formData) => {
  const title = formData.get("title");
  if (!title || title.length < 2) {
    return {
      error: "Title must be at least 2 characters",
    };
  }
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const submission = useSubmission(addPost);
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <Show when={submission.result?.error}>
        <p>{submission.result?.error}</p>
      </Show>
      <button>Add Post</button>
    </form>
  );
}

Showing optimistic UI

To update the UI before the server responds:

Import useSubmission from @solidjs/router.
Call useSubmission with your action, and use the returned pending and input properties to display optimistic UI.

import { For, Show } from "solid-js";
import { action, useSubmission, query, createAsync } from "@solidjs/router";

const getPosts = query(async () => {
  const posts = await fetch("https://my-api.com/blog");
  return await posts.json();
}, "posts");

const addPost = action(async (formData: FormData) => {
  const title = formData.get("title");
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const posts = createAsync(() => getPosts());
  const submission = useSubmission(addPost);
  return (
    <main>
      <form action={addPost} method="post">
        <input name="title" />
        <button>Add Post</button>
      </form>
      <ul>
        <For each={posts()}>{(post) => <li>{post.title}</li>}</For>
        <Show when={submission.pending}>
          {submission.input?.[0]?.get("title")?.toString()}
        </Show>
      </ul>
    </main>
  );
}

import { For, Show } from "solid-js";
import { action, useSubmission, query, createAsync } from "@solidjs/router";

const getPosts = query(async () => {
  const posts = await fetch("https://my-api.com/blog");
  return await posts.json();
}, "posts");

const addPost = action(async (formData) => {
  const title = formData.get("title");
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const posts = createAsync(() => getPosts());
  const submission = useSubmission(addPost);
  return (
    <main>
      <form action={addPost} method="post">
        <input name="title" />
        <button>Add Post</button>
      </form>
      <ul>
        <For each={posts()}>{(post) => <li>{post.title}</li>}</For>
        <Show when={submission.pending}>
          {submission.input?.[0]?.get("title")?.toString()}
        </Show>
      </ul>
    </main>
  );
}

Multiple Submissions

If you want to display optimistic UI for multiple concurrent submissions, you can use the useSubmissions primitive.

Redirecting

To redirect users to a different route within an action:

Import redirect from @solidjs/router.
Call redirect with the route you want to navigate to, and throw its response.

import { action, redirect } from "@solidjs/router";

const addPost = action(async (formData: FormData) => {
  const title = formData.get("title") as string;
  const response = await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
  const post = await response.json();
  throw redirect(`/posts/${post.id}`);
}, "addPost");

export default function Page() {
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

import { action, redirect } from "@solidjs/router";

const addPost = action(async (formData) => {
  const title = formData.get("title");
  const response = await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
  const post = await response.json();
  throw redirect(`/posts/${post.id}`);
}, "addPost");

export default function Page() {
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

Using a database or an ORM

To safely interact with your database or ORM in an action, ensure it's server-only by adding "use server" as the first line of your action:

import { action } from "@solidjs/router";
import { db } from "~/lib/db";

const addPost = action(async (formData: FormData) => {
  "use server";
  const title = formData.get("title") as string;
  await db.insert("posts").values({ title });
}, "addPost");

export default function Page() {
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

import { action } from "@solidjs/router";
import { db } from "~/lib/db";

const addPost = action(async (formData) => {
  "use server";
  const title = formData.get("title");
  await db.insert("posts").values({ title });
}, "addPost");

export default function Page() {
  return (
    <form action={addPost} method="post">
      <input name="title" />
      <button>Add Post</button>
    </form>
  );
}

Invoking an action programmatically

To programmatically invoke an action:

Import useAction from @solidjs/router.
Call useAction with your action, and use the returned function to invoke the action.

import { createSignal } from "solid-js";
import { action, useAction } from "@solidjs/router";

const addPost = action(async (title: string) => {
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const [title, setTitle] = createSignal("");
  const addPostAction = useAction(addPost);
  return (
    <div>
      <input value={title()} onInput={(e) => setTitle(e.target.value)} />
      <button onClick={() => addPostAction(title())}>Add Post</button>
    </div>
  );
}

import { createSignal } from "solid-js";
import { action, useAction } from "@solidjs/router";

const addPost = action(async (title) => {
  await fetch("https://my-api.com/posts", {
    method: "POST",
    body: JSON.stringify({ title }),
  });
}, "addPost");

export default function Page() {
  const [title, setTitle] = createSignal("");
  const addPostAction = useAction(addPost);
  return (
    <div>
      <input value={title()} onInput={(e) => setTitle(e.target.value)} />
      <button onClick={() => addPostAction(title())}>Add Post</button>
    </div>
  );
}

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