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