Files (addressing something the app stores)

The platform stores a file two ways, and which one you hold decides how you address it. A PATH-keyed file lives at an address you chose and becomes a URL with `File.Url` (public) or `File.SignedUrl` (a time-limited grant to one caller). A `FileAsset` is a ROW with its own security and NO path at all — neither of those verbs can address one; you put it on a page with `Image(fileAsset: row.Photo.Id)` and the platform works the address out.

Summary#

There are two stores, and the first thing to know is which one you are holding.

what you have	how it is addressed	shown with
a path — `"public/logo.png"`, an upload result	`File.Url(path)` · `File.SignedUrl(path)`	`Image(src: File.Url(path))`
a `FileAsset` — a row, from `File.Create` or `Image.Thumbnail`, or a `FileAsset` field	it has no path; the platform addresses it	`Image(fileAsset: row.Photo.Id)` — see Showing a picture on a page

⚠ The verbs on this page take a path string. A FileAsset carries none, so File.Url(asset) and File.SignedUrl(asset) do not exist and the compiler refuses them — that is the commonest first-day mistake, and Showing a picture on a page is what you wanted.

Within the path store, a stored file is addressed by URL, and which URL you ask for is an access decision.

using Osysharp.Storage;

[Principal] entity User { [MaxLength(200)] string Email; }

entity Item { [Required, MaxLength(200)] string ImagePath; }

// Anyone may fetch this — it is an asset, served to whoever asks.
string PublicImage(Item item) { return File.Url(item.ImagePath); }

// This one belongs to somebody, so the URL carries its own expiring grant.
string PrivateReport(User user) { return File.SignedUrl("reports/" + user.Id + "/q3.pdf"); }

Description#

File.Url is pure sugar over the serving route — an app-relative path becomes /_osy/files/…, which means it works directly inside a render argument. It grants nothing: what it addresses is served to whoever asks, so it is right for assets and wrong for anything a person owns.

File.SignedUrl is the other case, and it is the one to reach for by default when the file belongs to somebody: the URL carries its own time-limited grant, so sharing it is a decision with an expiry rather than a permanent one.

Files (addressing something the app stores)

Summary#

Description#

See also#

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