calesthio/OpenMontage · error · ValueError

Candidate {candidate.clip_id} has no download_url

Error message

Candidate {candidate.clip_id} has no download_url

What it means

ValueError raised by the Archive.org adapter's download() when the Candidate object has a falsy download_url. Search results can reference items whose file list did not yield a direct downloadable URL; the adapter refuses to guess (Archive.org item pages are not direct media) and fails before opening the network stream.

Source

Thrown at tools/video/stock_sources/archive_org.py:191

            for doc in docs:
                cand = self._hydrate_candidate(doc, filters)
                if cand is not None:
                    out.append(cand)
            if out:
                return out

        return []

    def download(self, candidate: Candidate, out_path: Path) -> Path:
        """Stream the candidate's file to `out_path`.

        Same pattern as the Pexels adapter — no caching, corpus builder
        decides.
        """
        import requests  # lazy

        if not candidate.download_url:
            raise ValueError(
                f"Candidate {candidate.clip_id} has no download_url"
            )

        out_path = Path(out_path)
        out_path.parent.mkdir(parents=True, exist_ok=True)

        with requests.get(
            candidate.download_url, stream=True, timeout=300
        ) as r:
            r.raise_for_status()
            with open(out_path, "wb") as f:
                for chunk in r.iter_content(chunk_size=1 << 16):
                    if chunk:
                        f.write(chunk)
        return out_path

    # ------------------------------------------------------------------
    # Internals

View on GitHub (pinned to 95e1c3d0ab)

Solutions

  1. Re-run search to get fresh candidates with populated download_url instead of reusing stale ones.
  2. Filter candidates before download: skip any where not candidate.download_url.
  3. If building candidates manually, always set download_url from the Archive.org file metadata (e.g. the 'url' of an ident'd file).

Example fix

# before
for c in candidates:
    path = source.download(c, out)

# after
for c in candidates:
    if not c.download_url:
        continue
    path = source.download(c, out)
Defensive patterns

Strategy: validation

Validate before calling

candidates = [c for c in candidates if getattr(c, "download_url", None)]

Type guard

def is_downloadable(candidate) -> bool:
    return bool(getattr(candidate, "download_url", None))

Try / catch

try:
    path = source.download(candidate, out_path)
except ValueError as e:
    if "no download_url" in str(e):
        continue  # skip bad candidate in batch loop
    raise

Prevention

When it happens

Trigger: A candidate produced by search whose download_url was never populated (metadata lacking a playable file), candidates constructed manually in tests/scripts with only clip_id set, or stale candidates serialized before a schema change that renamed the URL field.

Common situations: Pipeline code that reuses candidates across sessions after pickling; deserialized candidates from an older schema; Archive.org items with restricted or derivative-only files.

Related errors

AI-assisted analysis of calesthio/OpenMontage@95e1c3d0ab (2026-08-15). Data as JSON: /api/errors/365764d6da129143. Report an issue: GitHub.