File Uploads

This guide shows you how to implement file uploads in your Wasp application using Multer.

Setting up File Uploads

1. Install Multer

Install the Multer package and its types:

bash

npm install multer
npm install --save-dev @types/multer

2. Define the API endpoint in main.wasp.ts

Create an API namespace with middleware configuration and the upload endpoint:

import { api, apiNamespace, app, page, route } from "@wasp.sh/spec"
import { configureFileUploadMiddleware, uploadFile } from "./src/apis" with { type: "ref" }
import { MainPage } from "./src/MainPage" with { type: "ref" }

export default app({
  // ...
  spec: [
    route("RootRoute", "/", page(MainPage)),
    // highlight-start
    apiNamespace("/api/upload", { middlewareConfigFn: configureFileUploadMiddleware }),
    api("POST", "/api/upload", uploadFile),
    // highlight-end
  ],
})

3. Create the API handlers

Create the middleware configuration and upload handler:

import type { MiddlewareConfigFn } from "wasp/server";
import type { UploadFile } from "wasp/server/api";
import multer from "multer";

const upload = multer({ dest: "uploads/" });

export const configureFileUploadMiddleware: MiddlewareConfigFn = (config) => {
  config.set("multer", upload.single("file"));
  return config;
};

export const uploadFile: UploadFile = (req, res) => {
  console.log(req.body);
  console.log(req.file);
  const file = req.file!;
  return res.json({
    fileExists: !!file,
  });
};

4. Create the upload form

Create a form component to handle file uploads:

tsx

import { useState } from "react";
import { api } from "wasp/client/api";

export const MainPage = () => {
  const [name, setName] = useState("");
  const [file, setFile] = useState<File>();

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!file) return;
    const formData = new FormData();
    formData.append("name", name);
    formData.append("file", file);
    const data = await api
      .post("/api/upload", { body: formData })
      .json<{ fileExists: boolean }>();
    alert(JSON.stringify(data, null, 2));
  };

  return (
    <form onSubmit={handleSubmit}>
      <input
        type="text"
        placeholder="Name"
        value={name}
        onChange={(e) => setName(e.target.value)}
      />
      <input type="file" onChange={(e) => setFile(e.target.files?.[0])} />
      <button type="submit">Upload</button>
    </form>
  );
};

Customizing Upload Settings

Change upload destination

You can customize where files are stored:

const upload = multer({ dest: "my-custom-uploads/" });

Limit file size

Add file size limits:

const upload = multer({
  dest: "uploads/",
  limits: {
    fileSize: 5 * 1024 * 1024, // 5MB limit
  },
});

Filter file types

Only accept certain file types:

const upload = multer({
  dest: "uploads/",
  fileFilter: (req, file, cb) => {
    if (file.mimetype.startsWith("image/")) {
      cb(null, true);
    } else {
      cb(new Error("Only images are allowed"));
    }
  },
});

Handle multiple files

To handle multiple file uploads:

export const configureFileUploadMiddleware: MiddlewareConfigFn = (config) => {
  config.set("multer", upload.array("files", 10)); // Max 10 files
  return config;
};

For more options, see the Multer documentation.