cad-blob-uploader

Register BlobServiceClient as a singleton in DI, then in the controller accept an IFormFile, call file.OpenReadStream(), and pass the stream to blob.UploadAsync with BlobHttpHeaders for the content type. Streaming avoids loading the whole file into memory.

A SAS (Shared Access Signature) URL is a blob URL with cryptographically signed query parameters granting one permission, such as read, for a limited time. The client downloads directly from Azure, so the API never streams the file bytes itself.

BlobServiceClient should be registered as a singleton because it is thread-safe and expensive to create, holding HTTP connection pools. This contrasts with EF Core DbContext, which is scoped because it is not thread-safe.

Yes, Azurite is a free local emulator that runs in Docker or as a VS Code extension and exposes the same API surface as real Blob Storage. The connection string UseDevelopmentStorage=true points the SDK at it on port 10000.

Storing files in the database inflates row sizes, balloons backups, and slows queries on the most expensive storage you own. The database should hold only the blob name and content type as a reference, while the bytes live in object storage.

The endpoint is likely missing the [Consumes("multipart/form-data")] attribute, so ASP.NET Core rejects form-data requests. Adding it also enables Swagger UI to render a file upload widget for testing.