Routes

Request Body

Zeta automatically parses the request body into a useful type based on the Content-Type header.

Content Types

The Content-Type header is required on all requests with a body. If it is not present, ctx.body will always be undefined, even when a body was sent.

JSON

This is the most common content type, and Zeta uses your validation library to validate the body before it reaches the route's handler.

import { z } from "zod";

const app = createApp().post(
  "/auth/user",
  {
    body: z.object({
      username: z.string().min(2).max(100),
      email: z.email(),
      password: z.string().min(8).max(100),
    }),
  },
  ({ body }) => {
    console.log(body); // { username: "...", email: "...", password: "..." }
  },
);

Most of the time the body will be an object, but it can be any valid JSON value, like a number, string, array, boolean, etc.

WARNING

Devs forget to set the Content-Type header when using fetch directly with a JSON body. If you forget, the body will be undefined in the handler!

File

Zeta provides a util for parsing single file uploads: UploadFileBody. When used as the body schema, the body variable will be an instance of the File class.

import { UploadFileBody } from "@aklinker1/zeta/schemas";

const app = createApp().post(
  "/upload",
  {
    body: UploadFileBody,
  },
  ({ body }) => {
    console.log(body); // File { ... }
  },
);

On the client side, the body needs to be passed as a FormData object with a single key, file:

const formData = new FormData();
formData.append("file", file);

// No need to set the `Content-Type` header when using FormData
await fetch("/upload", {
  method: "POST",
  body: formData,
});

Or you can use Zeta's built-in client which will build the FormData for you.

Files

Similar to individual file uploads, Zeta provides a util for uploading FileLists: UploadFilesBody.

import { UploadFilesBody } from "@aklinker1/zeta/schemas";

const app = createApp().post(
  "/upload",
  {
    body: UploadFilesBody,
  },
  ({ body }) => {
    console.log(body); // File[]
  },
);

In the handler, instead of a FileList, you'll be provided a File[].

On the client side, the body is still FormData, but the key is files instead:

const formData = new FormData();
files.forEach((file) => {
  formData.append("files", file);
});

// No need to set the `Content-Type` header when using FormData
await fetch("/upload", {
  method: "POST",
  body: formData,
});

And once again, you can use Zeta's built-in client which will build the FormData for you based on an input FileList.

FormData

To upload a generic FormData object, you can use the FormDataBody util.

import { FormDataBody } from "@aklinker1/zeta/schemas";

const app = createApp().post(
  "/upload",
  {
    body: FormDataBody,
  },
  ({ body }) => {
    console.log(body); // FormData { ... }
  },
);

Other

If you need to upload another data type, like CSV, you can do so by adding the contentType metadata to your body schema:

import { z } from "zod";

const app = createApp().post(
  "/upload/csv",
  {
    body: z.string().meta({ contentType: "text/csv" }),
  },
  ({ body }) => {
    console.log(body); // "..."
  },
);

Zeta can deserialize the following content types:

• application/json → any
• multipart/form-data → FormData
• text/* → string
• application/x-www-form-urlencoded → FormData
• application/octet-stream → Buffer

If the content type is not supported, Zeta will throw an error.