How to save the uploaded file to a folder?

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04-09-2024

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Saving Uploaded Files in Rust with async-graphql and actix-web

This article will guide you through saving uploaded files to a folder using Rust, specifically with the popular libraries async-graphql and actix-web. We'll build upon a Stack Overflow question found here to demonstrate the process.

Understanding the Code

The code snippet provided from Stack Overflow defines a function single_upload which is designed to receive an uploaded file via GraphQL using async-graphql. It does the following:

1. Retrieves the file: It uses file.value(ctx).unwrap() to access the uploaded file data.
2. Creates file information: It generates a FileInfo struct containing the file's ID, filename, and mime type.
3. Stores file information: It inserts the FileInfo into a FileStorage data structure, effectively registering the uploaded file.

Saving the File to a Folder

The code above only handles the information about the uploaded file, not the actual file contents. To save the file to a folder, we'll need to add the following steps:

1. Read the file data: Access the file's contents as a byte stream using the read method provided by the Upload type.
2. Create a file path: Construct the path to the desired folder and append the filename to create the complete path.
3. Write the data to the file: Use a library like std::fs or tokio::fs to write the file data to the specified path.

Example Implementation

use async_graphql::{Context, Upload};
use actix_web::web::Data;
use std::fs::File;
use std::io::{Read, Write};
use tokio::fs::File as AsyncFile;

#[derive(Debug, Clone)]
struct FileStorage {
    // ... (Implementation for storing file information)
}

#[derive(Debug, Clone, PartialEq)]
struct FileInfo {
    id: String,
    filename: String,
    mimetype: String,
}

async fn single_upload(&self, ctx: &Context<'_>, file: Upload) -> FileInfo {
    let mut storage = ctx.data_unchecked::<FileStorage>().lock().await;
    let upload = file.value(ctx).unwrap();
    let info = FileInfo {
        id: ... // Generate unique ID
        filename: upload.filename.clone(),
        mimetype: upload.content_type,
    };

    // Read file contents
    let mut file_data = Vec::new();
    upload.read(&mut file_data).unwrap();

    // Create file path
    let path = format!("./uploads/{}", info.filename);
    
    // Save the file to disk
    let mut f = AsyncFile::create(path).await.unwrap();
    f.write_all(&file_data).await.unwrap();

    storage.insert(info.clone());
    info
}

Explanation:

• File Data Retrieval: The code first retrieves the file data as a byte stream using upload.read(&mut file_data).
• File Path Construction: It then builds the desired file path using the specified folder ("./uploads/") and the file's name.
• File Writing: The code creates a file with the specified path and writes the file data into it.

Important Considerations:

• Error Handling: Always implement robust error handling to catch potential issues during file reading, path creation, or file writing.
• File Security: Implement measures to prevent malicious uploads and ensure proper file permissions.
• File Storage Management: Implement a robust strategy for managing uploaded files, including potentially deleting old files, enforcing size limits, and providing a mechanism to retrieve uploaded files.

Conclusion

This article provided a comprehensive guide on saving uploaded files to a folder using async-graphql and actix-web in Rust. Remember to incorporate appropriate error handling, security measures, and file management strategies to ensure a robust and secure solution.