File API - Elixir SDK Documentation

Overview

The File API provides endpoints for downloading and accessing files stored in collection records. It supports thumbnail generation for images, protected file access with tokens, and force download options.

Key Features:

Download files from collection records
Generate thumbnails for images (crop, fit, resize)
Protected file access with short-lived tokens
Force download option for any file type
Automatic content-type detection
Support for Range requests and caching

Backend Endpoints:

GET /api/files/{collection}/{recordId}/{filename} - Download/fetch file
POST /api/files/token - Generate protected file token

Download / Fetch File

Downloads a single file resource from a record.

Basic Usage

alias Bosbase.Client

pb = Client.new("http://127.0.0.1:8090")

# Get a record with a file field
{:ok, record} = Client.collection(pb, "posts")
  |> Bosbase.RecordService.get_one("RECORD_ID")

# Get the file URL
file_url = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"])

IO.puts("File URL: #{file_url}")

File URL Structure

The file URL follows this pattern:

/api/files/{collectionIdOrName}/{recordId}/{filename}

Example:

http://127.0.0.1:8090/api/files/posts/abc123/photo_xyz789.jpg

Thumbnails

Generate thumbnails for image files on-the-fly.

Thumbnail Formats

The following thumbnail formats are supported:

Format	Example	Description
`WxH`	`100x300`	Crop to WxH viewbox (from center)
`WxHt`	`100x300t`	Crop to WxH viewbox (from top)
`WxHb`	`100x300b`	Crop to WxH viewbox (from bottom)
`WxHf`	`100x300f`	Fit inside WxH viewbox (without cropping)
`0xH`	`0x300`	Resize to H height preserving aspect ratio
`Wx0`	`100x0`	Resize to W width preserving aspect ratio

Using Thumbnails

# Get thumbnail URL
thumb_url = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"], %{
    "thumb" => "100x100"
  })

# Different thumbnail sizes
small_thumb = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"], %{
    "thumb" => "50x50"
  })

medium_thumb = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"], %{
    "thumb" => "200x200"
  })

large_thumb = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"], %{
    "thumb" => "500x500"
  })

# Fit thumbnail (no cropping)
fit_thumb = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"], %{
    "thumb" => "200x200f"
  })

# Resize to specific width
width_thumb = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"], %{
    "thumb" => "300x0"
  })

# Resize to specific height
height_thumb = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["image"], %{
    "thumb" => "0x200"
  })

Thumbnail Behavior

Image Files Only: Thumbnails are only generated for image files (PNG, JPG, JPEG, GIF, WEBP)
Non-Image Files: For non-image files, the thumb parameter is ignored and the original file is returned
Caching: Thumbnails are cached and reused if already generated
Fallback: If thumbnail generation fails, the original file is returned
Field Configuration: Thumb sizes must be defined in the file field’s thumbs option or use default 100x100

Protected Files

Protected files require a special token for access, even if you’re authenticated.

Getting a File Token

# Must be authenticated first
{:ok, _auth} = Client.collection(pb, "users")
  |> Bosbase.RecordService.auth_with_password("user@example.com", "password")

# Get file token
{:ok, token_response} = Bosbase.files()
  |> Bosbase.FileService.get_token(pb)

token = token_response["token"]
IO.puts("Token: #{token}")  # Short-lived JWT token

Using Protected File Token

# Get protected file URL with token
protected_file_url = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["document"], %{
    "token" => token
  })

# Access the file (using HTTPoison or similar)
# {:ok, response} = HTTPoison.get(protected_file_url)

Protected File Example

def display_protected_image(pb, record_id) do
  # Authenticate
  {:ok, _auth} = Client.collection(pb, "users")
    |> Bosbase.RecordService.auth_with_password("user@example.com", "password")
  
  # Get record
  {:ok, record} = Client.collection(pb, "documents")
    |> Bosbase.RecordService.get_one(record_id)
  
  # Get file token
  {:ok, token_response} = Bosbase.files()
    |> Bosbase.FileService.get_token(pb)
  
  token = token_response["token"]
  
  # Get protected file URL
  image_url = Bosbase.files()
    |> Bosbase.FileService.get_url(pb, record, record["thumbnail"], %{
      "token" => token,
      "thumb" => "300x300"
    })
  
  IO.puts("Image URL: #{image_url}")
end

Token Lifetime

File tokens are short-lived (typically expires after a few minutes)
Tokens are associated with the authenticated user/superuser
Generate a new token if the previous one expires

Force Download

Force files to download instead of being displayed in the browser.

# Force download
download_url = Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, record["document"], %{
    "download" => true
  })

IO.puts("Download URL: #{download_url}")

Download Parameter Values

# These all force download:
Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, filename, %{"download" => true})

Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, filename, %{"download" => 1})

# These allow inline display (default):
Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, filename, %{"download" => false})

Bosbase.files()
  |> Bosbase.FileService.get_url(pb, record, filename)  # No download parameter

Complete Examples

Example 1: Image Gallery

def display_image_gallery(pb, record_id) do
  {:ok, record} = Client.collection(pb, "posts")
    |> Bosbase.RecordService.get_one(record_id)
  
  images = if is_list(record["images"]), do: record["images"], else: [record["image"]]
  
  Enum.each(images, fn filename ->
    # Thumbnail for gallery
    thumb_url = Bosbase.files()
      |> Bosbase.FileService.get_url(pb, record, filename, %{
        "thumb" => "200x200"
      })
    
    # Full image URL
    full_url = Bosbase.files()
      |> Bosbase.FileService.get_url(pb, record, filename)
    
    IO.puts("Thumbnail: #{thumb_url}")
    IO.puts("Full: #{full_url}")
  end)
end

Example 2: File Download Handler

def download_file(pb, record_id, filename) do
  {:ok, record} = Client.collection(pb, "documents")
    |> Bosbase.RecordService.get_one(record_id)
  
  # Get download URL
  download_url = Bosbase.files()
    |> Bosbase.FileService.get_url(pb, record, filename, %{
      "download" => true
    })
  
  IO.puts("Download URL: #{download_url}")
  # Use HTTPoison or similar to download the file
end

Example 3: Protected File Viewer

def view_protected_file(pb, record_id) do
  # Authenticate
  {:ok, _auth} = Client.collection(pb, "users")
    |> Bosbase.RecordService.auth_with_password("user@example.com", "password")
  
  # Get record
  {:ok, record} = Client.collection(pb, "private_docs")
    |> Bosbase.RecordService.get_one(record_id)
  
  # Get token
  case Bosbase.files()
       |> Bosbase.FileService.get_token(pb) do
    {:ok, token_response} ->
      token = token_response["token"]
      
      # Get file URL
      file_url = Bosbase.files()
        |> Bosbase.FileService.get_url(pb, record, record["file"], %{
          "token" => token
        })
      
      IO.puts("File URL: #{file_url}")
    {:error, error} ->
      IO.puts("Failed to get file token: #{inspect(error)}")
  end
end

Error Handling

case Bosbase.files()
     |> Bosbase.FileService.get_url(pb, record, record["image"]) do
  url when is_binary(url) ->
    IO.puts("File URL: #{url}")
  {:error, error} ->
    IO.puts("File access error: #{inspect(error)}")
end

Protected File Token Error Handling

def get_protected_file_url(pb, record, filename) do
  case Bosbase.files()
       |> Bosbase.FileService.get_token(pb) do
    {:ok, token_response} ->
      token = token_response["token"]
      Bosbase.files()
        |> Bosbase.FileService.get_url(pb, record, filename, %{"token" => token})
    {:error, %{status: 401}} ->
      IO.puts("Not authenticated")
      nil
    {:error, %{status: 403}} ->
      IO.puts("No permission to access file")
      nil
    {:error, error} ->
      IO.puts("Failed to get file token: #{inspect(error)}")
      nil
  end
end

Best Practices

Use Thumbnails for Lists: Use thumbnails when displaying images in lists/grids to reduce bandwidth
Lazy Loading: Consider lazy loading for images below the fold
Cache Tokens: Store file tokens and reuse them until they expire
Error Handling: Always handle file loading errors gracefully
Content-Type: Let the server handle content-type detection automatically
Range Requests: The API supports Range requests for efficient video/audio streaming
Caching: Files are cached with a 30-day cache-control header
Security: Always use tokens for protected files, never expose them in client-side code

Thumbnail Size Guidelines

Use Case	Recommended Size
Profile picture	`100x100` or `150x150`
List thumbnails	`200x200` or `300x300`
Card images	`400x400` or `500x500`
Gallery previews	`300x300f` (fit) or `400x400f`
Hero images	Use original or `800x800f`
Avatar	`50x50` or `75x75`

Limitations

Thumbnails: Only work for image files (PNG, JPG, JPEG, GIF, WEBP)
Protected Files: Require authentication to get tokens
Token Expiry: File tokens expire after a short period (typically minutes)
File Size: Large files may take time to generate thumbnails on first request
Thumb Sizes: Must match sizes defined in field configuration or use default 100x100

Files Upload and Handling - Uploading and managing files
API Records - Working with records
Collections - Collection configuration