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Refresh Metadata

The refresh_metadata plugin allows you to re-extract metadata from an uploaded file.

plugin :refresh_metadata

It provides #refresh_metadata! method, which triggers metadata extraction (calls Shrine#extract_metadata) with the uploaded file opened for reading, and updates the existing metadata hash with the results. This can be done on the Shrine::Attacher or the Shrine::UploadedFile level.

Attacher​

Calling #refresh_metadata! on a Shrine::Attacher object will re-extract metadata of the attached file, and when used with a model, it will write new file data back into the attachment attribute.

attacher.refresh_metadata!
attacher.file.metadata    # re-extracted metadata
attacher.record.file_data #=> '{ ... data with updated metadata ... }'

The Attacher#context hash will be forwarded to metadata extraction, as well as any options that you pass in.

# via context
attacher.context[:foo] = "bar"
attacher.refresh_metadata! # passes `{ foo: "bar" }` options to metadata extraction

# via arguments
attacher.refresh_metadata!(foo: "bar") # passes `{ foo: "bar" }` options to metadata extraction

Uploaded File​

The #refresh_metadata! method can be called on a Shrine::UploadedFile object as well.

uploaded_file.refresh_metadata!
uploaded_file.metadata # re-extracted metadata

If the uploaded file is not open, it is opened before and closed after metadata extraction. For remote storage services this will make an HTTP request. However, only the portion of the file needed for extracting metadata will be downloaded.

If the uploaded file is already open, it is passed to metadata extraction as is.

uploaded_file.open do
  uploaded_file.refresh_metadata! # uses the already opened file
  # ...
end

Any options passed in will be forwarded to metadata extraction:

uploaded_file.refresh_metadata!(foo: "bar") # passes `{ foo: "bar" }` options to metadata extraction