GCS Rust SDK Download Object API

Problem

When using the google-cloud-storage Rust crate to download objects, developers often look for a DownloadObjectRequest type in the download module, expecting it to mirror the upload pattern. This type doesn't exist, causing confusing compile errors.

Context / Trigger Conditions

• Using google-cloud-storage crate in Rust
• Trying to call client.download_object()
• Error: unresolved import google_cloud_storage::http::objects::download::DownloadObjectRequest
• Looking in http::objects::download module for request types

Solution

The download_object method uses GetObjectRequest from the get module, combined with Range from the download module:

use google_cloud_storage::http::objects::{
    download::Range as DownloadRange,
    get::GetObjectRequest,
};

// Download full object
let data = client.download_object(
    &GetObjectRequest {
        bucket: "my-bucket".to_string(),
        object: "path/to/object".to_string(),
        ..Default::default()
    },
    &DownloadRange::default(),
).await?;

// Download partial object (bytes 0-1023)
let partial = client.download_object(
    &GetObjectRequest {
        bucket: "my-bucket".to_string(),
        object: "path/to/object".to_string(),
        ..Default::default()
    },
    &DownloadRange::Bounded(0, 1023),
).await?;

Verification

Code compiles and download_object returns Vec<u8> with the object contents.

Example

use google_cloud_storage::{
    client::{Client as GcsClient, ClientConfig},
    http::objects::{
        download::Range as DownloadRange,
        get::GetObjectRequest,
        upload::{Media, UploadObjectRequest, UploadType},
    },
};

async fn download_from_gcs(client: &GcsClient, bucket: &str, key: &str) -> Result<Vec<u8>> {
    let data = client.download_object(
        &GetObjectRequest {
            bucket: bucket.to_string(),
            object: key.to_string(),
            ..Default::default()
        },
        &DownloadRange::default(),
    ).await?;

    Ok(data)
}

Notes

• The Range type is aliased as DownloadRange to avoid conflicts with std::ops::Range
• DownloadRange::default() downloads the entire object
• For checking if an object exists without downloading, use get_object with GetObjectRequest
• The Media.content_type field is Cow<'static, str>, use .into() for string conversion

References

• google-cloud-storage crate docs