#Files handling

10 messages · Page 1 of 1 (latest)

muted peak Oct 26, 2024, 2:25 PM

I want the ability for users to upload files (txt) I want to store it in convex and then in an action get the file contents and for each line inside the text add it to an array (split lines) then call and API inside that action

main garnetBOT Oct 26, 2024, 2:25 PM

Hi @muted peak. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:

Certainly! Convex provides file storage capabilities that allow users to upload files, store them, and then process them in actions. Here's how you can achieve what you're looking for:

File Upload:
Users can upload files to Convex using generated upload URLs. This process involves three steps:

a) Generate an upload URL using a mutation that calls storage.generateUploadUrl().
b) Send a POST request with the file contents to the upload URL.
c) Save the returned storage ID in your database.

Here's an example of how to implement file upload from a web page:

import { FormEvent, useRef, useState } from "react";
import { useMutation } from "convex/react";
import { api } from "../convex/_generated/api";

export default function App() {
  const generateUploadUrl = useMutation(api.messages.generateUploadUrl);
  const sendFile = useMutation(api.messages.sendFile);

  const fileInput = useRef<HTMLInputElement>(null);
  const [selectedFile, setSelectedFile] = useState<File | null>(null);

  async function handleSendFile(event: FormEvent) {
    event.preventDefault();

    // Step 1: Get a short-lived upload URL
    const postUrl = await generateUploadUrl();
    // Step 2: POST the file to the URL
    const result = await fetch(postUrl, {
      method: "POST",
      headers: { "Content-Type": selectedFile!.type },
      body: selectedFile,
    });
    const { storageId } = await result.json();
    // Step 3: Save the newly allocated storage id to the database
    await sendFile({ storageId, fileName: selectedFile!.name });

    setSelectedFile(null);
    fileInput.current!.value = "";
  }

return (
<form onSubmit={handleSendFile}>
<input
type="file"
accept=".txt"
ref={fileInput}
onChange={(event) => setSelectedFile(event.target.files![0])}
disabled={selectedFile !== null}
/>
<input
type="submit"
value="Send File"
disabled={selectedFile === null}
/>
</form>
);
}


**File-storage > Uploading and Storing Files > Uploading files via upload URLs > Calling the upload APIs from a web page** (<https://docs.convex.dev/file-storage/upload-files#calling-the-upload-apis-from-a-web-page>)

2. Processing the File in an Action:
Once the file is uploaded and stored in Convex, you can create an action to process its contents. Here's an outline of how you can implement this:

```typescript
import { action } from "./_generated/server";
import { api } from "./_generated/api";

export const processFile = action(async (ctx, { storageId }) => {
  // Fetch the file contents
  const file = await ctx.storage.get(storageId);
  if (!file) {
    throw new Error("File not found");
  }

  // Convert the file to text
  const text = await file.text();

  // Split the text into lines
  const lines = text.split('\n');

  // Call your API here with the lines array
  // const apiResult = await callYourAPI(lines);

  // You can then store the result or perform further operations
  // await ctx.runMutation(api.yourTable.storeLinesResult, { result: apiResult });

  return lines.length; // or return whatever is appropriate
});

This action does the following:

Retrieves the file from Convex storage using the storageId.
Converts the file to text.
Splits the text into lines, creating an array.
You can then call your API with this array (you'll need to implement this part).
Finally, you can store the result or perform any other necessary operations.

Remember to handle potential errors, such as file not found or processing errors.

File Storage (https://docs.convex.dev/file-storage)
Storing Generated Files (https://docs.convex.dev/file-storage/store-files)

Note that file storage is currently a beta feature in Convex. If you encounter any issues or have feature requests, it's recommended to reach out to the Convex community for support.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@muted peak Kapa.ai is still learning and improving, please let me know how I did by reacting below.

muted peak Oct 26, 2024, 2:29 PM

@main garnet
Now let’s say I have already a function with a downloadUrl in a variable already set (from external resource) I want to download it directly to convex storage and get storage id?

main garnetBOT Oct 26, 2024, 2:29 PM

Let me check the knowledge base for you again. One moment! :books:

Certainly! You can download a file from an external URL and store it directly in Convex storage using an action. Here's how you can do it:

import { action, internalMutation } from "./_generated/server";
import { internal } from "./_generated/api";
import { v } from "convex/values";
import { Id } from "./_generated/dataModel";

export const downloadAndStore = action({
  args: { downloadUrl: v.string() },
  handler: async (ctx, args) => {
    // Download the file
    const response = await fetch(args.downloadUrl);
    const file = await response.blob();

    // Store the file in Convex
    const storageId: Id<"_storage"> = await ctx.storage.store(file);

    // Optionally, save the storageId to your database
    await ctx.runMutation(internal.files.saveFileInfo, {
      storageId,
      originalUrl: args.downloadUrl,
    });

    return storageId;
  },
});

// Optional: Save file info to your database
export const saveFileInfo = internalMutation({
  args: {
    storageId: v.id("_storage"),
    originalUrl: v.string(),
  },
  handler: async (ctx, args) => {
    await ctx.db.insert("files", {
      storageId: args.storageId,
      originalUrl: args.originalUrl,
    });
  },
});

This code does the following:

We define an action called downloadAndStore that takes a downloadUrl as an argument.
Inside the action, we use fetch to download the file from the provided URL.
We convert the downloaded file to a Blob object.
We use ctx.storage.store() to store the file in Convex storage and get a storageId.
Optionally, we save the storageId and original URL to our database using an internal mutation.

You can call this action from your client code like this:

const downloadAndStore = useMutation(api.files.downloadAndStore);

// ...

const storageId = await downloadAndStore({ downloadUrl: "https://example.com/file.txt" });


This approach allows you to download a file from an external URL and store it directly in Convex storage, getting the `storageId` in return. You can then use this `storageId` to access the file later or perform further operations.

**File-storage > Storing Generated Files > Storing files in actions** (<https://docs.convex.dev/file-storage/store-files#storing-files-in-actions>)
**Stack >  > Using Dall-E from Convex > Using OpenAI in Convex > Downloading the image** (<https://stack.convex.dev/using-dall-e-from-convex#downloading-the-image>)

Remember that when working with external URLs, you should implement proper error handling and consider potential issues like large file sizes or network failures.
----------------------
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
----------------------