Method UploadToS3

docs/test-csharp-snippets/Module.cs:243–294

Upload file to S3 and register in database

(
        ProcedureContext ctx,
        string filename,
        string contentType,
        List<byte> data,
        string s3Bucket,
        string s3Region)

    // Upload file to S3 and register in database
    [SpacetimeDB.Procedure]
    public static string UploadToS3(
        ProcedureContext ctx,
        string filename,
        string contentType,
        List<byte> data,
        string s3Bucket,
        string s3Region)
    {
        // Generate a unique S3 key
        var timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
        var s3Key = $"uploads/{timestamp}-{filename}";
        var url = $"https://{s3Bucket}.s3.{s3Region}.amazonaws.com/{s3Key}";

        // Build the S3 PUT request (simplified - add AWS4 signature in production)
        var request = new HttpRequest
        {
            Uri = url,
            Method = SpacetimeDB.HttpMethod.Put,
            Headers = new List<HttpHeader>
            {
                new HttpHeader("Content-Type", contentType),
                new HttpHeader("x-amz-content-sha256", "UNSIGNED-PAYLOAD"),
                // Add Authorization header with AWS4 signature
            },
            Body = new HttpBody(data.ToArray()),
        };

        // Upload to S3
        var response = ctx.Http.Send(request).UnwrapOrThrow();

        if (response.StatusCode != 200)
        {
            throw new Exception($"S3 upload failed with status: {response.StatusCode}");
        }

        // Store metadata in database
        ctx.WithTx(txCtx =>
        {
            txCtx.Db.Document.Insert(new Document
            {
                Id = 0,
                OwnerId = txCtx.Sender,
                Filename = filename,
                S3Key = s3Key,
                UploadedAt = txCtx.Timestamp,
            });
            return 0;
        });

        return s3Key;
    }

    // === Snippet 10: Pre-signed URL Flow ===
    [SpacetimeDB.Type]