Hash files

🤖/file/hash hashes files in Assemblies.

Usage example

{
  "steps": {
    "hashed": {
      "robot": "/file/hash",
      "use": ":original",
      "algorithm": "sha1"
    }
  }
}

Parameters

• output_meta

  Record<string, boolean> | boolean | Array<string>

  Allows you to specify a set of metadata that is more expensive on CPU power to calculate, and thus is disabled by default to keep your Assemblies processing fast.

  For images, you can add "has_transparency": true in this object to extract if the image contains transparent parts and "dominant_colors": true to extract an array of hexadecimal color codes from the image.

  For images, you can also add "blurhash": true to extract a BlurHash string — a compact representation of a placeholder for the image, useful for showing a blurred preview while the full image loads.

  For videos, you can add the "colorspace: true" parameter to extract the colorspace of the output video.

  For audio, you can add "mean_volume": true to get a single value representing the mean average volume of the audio file.

  You can also set this to false to skip metadata extraction and speed up transcoding.

• result

  boolean (default: false)

  Whether the results of this Step should be present in the Assembly Status JSON

• queue

  batch

  Setting the queue to 'batch', manually downgrades the priority of jobs for this step to avoid consuming Priority job slots for jobs that don't need zero queue waiting times

• force_accept

  boolean (default: false)

  Force a Robot to accept a file type it would have ignored.

  By default, Robots ignore files they are not familiar with. 🤖/video/encode, for example, will happily ignore input images.

  With the force_accept parameter set to true, you can force Robots to accept all files thrown at them. This will typically lead to errors and should only be used for debugging or combatting edge cases.

• ignore_errors

  boolean | Array<meta | execute> (default: [])

  Ignore errors during specific phases of processing.

  Setting this to ["meta"] will cause the Robot to ignore errors during metadata extraction.

  Setting this to ["execute"] will cause the Robot to ignore errors during the main execution phase.

  Setting this to true is equivalent to ["meta", "execute"] and will ignore errors in both phases.

• use

  string | Array<string> | Array<object> | object

  Specifies which Step(s) to use as input.

  • You can pick any names for Steps except ":original" (reserved for user uploads handled by Transloadit)
  • You can provide several Steps as input with arrays:
    

    {
      "use": [
        ":original",
        "encoded",
        "resized"
      ]
    }
    

  • You can also tag an input Step with as to pass semantic intent to robots:
  • You can also tag input Steps with as to pass semantic intent to robots:
    

    {
      "use": [
        {
          "name": ":original",
          "as": "image"
        },
        {
          "name": ":original",
          "as": "mask"
        }
      ]
    }
    

  Tip

  That's likely all you need to know about use, but you can view Advanced use cases.

• algorithm

  b2 | md5 | sha1 | sha224 | sha256 | sha384 | sha512 (default: "sha256")

  The hashing algorithm to use.

  The file hash is exported as file.meta.hash.

• partial

  full | first | last | both (default: "full")

  Specifies which portion of the file to hash. This is useful for fast fingerprinting of large files.

  • "full" (default): Hash the entire file.
  • "first": Hash only the first N bytes (specified by partial_size).
  • "last": Hash only the last N bytes (specified by partial_size).
  • "both": Hash the first N bytes concatenated with the last N bytes.

  When using partial hashing, file.meta.hash_partial indicates the mode used, and file.meta.hash_partial_size indicates the number of bytes hashed from each portion.

• partial_size

  string | number (default: 1048576)

  The number of bytes to hash when using partial hashing. Defaults to 1048576 (1 MB).

  This parameter is only used when partial is set to "first", "last", or "both".

Related blog posts