Mob.Storage (mob v0.6.2)

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App-local file storage.

Provides a thin Elixir wrapper over the device filesystem using named locations instead of raw paths. Basic file operations (list, stat, delete, copy, move, read, write) are pure File.* calls — no NIF overhead except for the initial dir/1 path resolution.

Locations

  • :temp — ephemeral; may be purged by the OS at any time
  • :documents — persists across app sessions; user-visible on iOS
                 when `UIFileSharingEnabled` is set (see `mix mob.enable`)
  • :cache — persists until OS needs space; not user-visible
  • :app_support — persists, hidden from user, backed up on iOS

Platform-specific storage

See Mob.Storage.Apple and Mob.Storage.Android for saving to the native photo/media library and accessing platform-specific directories.

Results

Operations that can fail return {:ok, value} | {:error, posix}. dir/1 raises on an unknown location atom.

Summary

Functions

copy(src, dest)

Copy src to dest.

delete(path)

Delete a file.

dir(location)

Resolve a location atom to its absolute path on the current device.

extension(path)

Return the file extension including the leading dot, or "" if none.

list(location)

List all files in a location or an absolute path.

move(src, dest)

Move src to dest.

read(path)

Read a file's contents as a binary.

stat(path)

Return metadata for a file.

write(path, data)

Write data to path.

Functions

copy(src, dest)

@spec copy(String.t(), atom() | String.t()) :: {:ok, String.t()} | {:error, atom()}

Copy src to dest.

dest may be a location atom (file is placed there keeping its basename) or a full absolute path.

Returns {:ok, dest_path} on success.

delete(path)

@spec delete(String.t()) :: :ok | {:error, atom()}

Delete a file.

dir(location)

@spec dir(atom()) :: String.t()

Resolve a location atom to its absolute path on the current device.

extension(path)

@spec extension(String.t()) :: String.t()

Return the file extension including the leading dot, or "" if none.

No I/O — derived from the filename only.

Mob.Storage.extension("/tmp/clip.mp4")   #=> ".mp4"
Mob.Storage.extension("/tmp/notes")      #=> ""

list(location)

@spec list(atom() | String.t()) :: {:ok, [String.t()]} | {:error, atom()}

List all files in a location or an absolute path.

Returns full paths, not just names.

move(src, dest)

@spec move(String.t(), atom() | String.t()) :: {:ok, String.t()} | {:error, atom()}

Move src to dest.

dest may be a location atom or a full absolute path.

Returns {:ok, dest_path} on success.

read(path)

@spec read(String.t()) :: {:ok, binary()} | {:error, atom()}

Read a file's contents as a binary.

stat(path)

@spec stat(String.t()) :: {:ok, map()} | {:error, atom()}

Return metadata for a file.

%{name: "clip.mp4", path: "/…/clip.mp4", size: 204_800,
  modified_at: ~U[2026-04-24 10:00:00Z]}

write(path, data)

@spec write(String.t(), binary()) :: {:ok, String.t()} | {:error, atom()}

Write data to path.

Returns {:ok, path} on success.