oarepo-previewer

OARepo module delivering contrib previewers to invenio-previewer for custom file extensions.

Installation

pip install oarepo-previewer

The Flask app extension (registered via the invenio_base.apps entry point) inserts the previewers listed in OAREPO_PREVIEWER_ENABLED at the front of invenio-previewer's PREVIEWER_PREFERENCE.

Shipped previewers

Molecular Viewer (mol)

A unified molecular structure previewer powered by Molstar, supporting a wide range of molecular and crystallographic file formats:

The previewer leverages Molstar's native support for these formats, providing 3D visualization directly in the browser. Configuration is handled via the template which loads Molstar and initializes the viewer with the file URI.

Configuration

# invenio.cfg
OAREPO_PREVIEWER_ENABLED = ["mol"]  # default
OAREPO_PREVIEWER_MOL_MAX_FILE_SIZE_BYTES = 200 * 1024 * 1024

Set OAREPO_PREVIEWER_ENABLED = [] to manage PREVIEWER_PREFERENCE manually.

Content Security Policy (Molstar)

Molstar may issue fetch calls to external databases when a previewed file (e.g. an .mvsj/.mvsx MolViewSpec description) contains URLs pointing to remote resources. If your app sets APP_DEFAULT_SECURE_HEADERS, the default Content Security Policy will block these requests, so the policy needs to be relaxed for the molecular viewer to work.

invenio.cfg settings could be for instance:

# invenio.cfg
APP_DEFAULT_SECURE_HEADERS = {
    "content_security_policy": {
        "default-src": [
            "'self'",
            "fonts.googleapis.com",
            "*.gstatic.com",
            "data:",
            "'unsafe-inline'",
            "blob:",
            "http://127.0.0.1:9000/",  # Development S3 server
            "https://licensebuttons.net/",
        ],
        "script-src": [
            "'self'",
            "blob:",
            "'wasm-unsafe-eval'",
        ],
        "connect-src": [
            "'self'",
            "http://127.0.0.1:9000",  # Development S3 server
            "https://*.rcsb.org",  # RCSB PDB (Protein Data Bank)
            "https://*.ebi.ac.uk",  # EBI (European Bioinformatics Institute)
            "https://*.pdbj.org",  # PDBj (Protein Data Bank Japan)
            "https://modelarchive.org",  # ModelArchive
            "https://*.expasy.org",  # ExPASy
            "https://pubchem.ncbi.nlm.nih.gov",  # PubChem
        ],
    }
}

The connect-src database entries are actually only needed if previewed files reference remote resources — Molstar fetches them from the databases above. If your records never contain such references, you can omit them (or add more if needed). Keep the development S3 entries (127.0.0.1:9000) out of production deployments and replace them with your actual file storage origin.

Adding a contrib previewer

1. Create a module in oarepo_previewer/previewers/ exposing previewable_extensions (list of extensions without a dot) and the can_preview(file) / preview(file) functions — see (invenio_previewer/extensions/json_prismjs.py) for the contract. Templates go to oarepo_previewer/templates/semantic-ui/oarepo_previewer/.

2. Register it in pyproject.toml:

   [project.entry-points."invenio_previewer.previewers"]
   mol = "oarepo_previewer.previewers.mol "
   

3. Add its name to the default OAREPO_PREVIEWER_ENABLED in oarepo_previewer/config.py.

Development

./run.sh --help   # oarepo library runner (tests, linting, ...)
./run.sh tests

License

MIT — Copyright (C) 2026 CESNET z.s.p.o. See the LICENSE file.