GROQ query for Mux video asset returning only _ref instead of full data

The issue you're encountering is a common one when working with Mux videos in Sanity! You're getting just a _ref because you need to use the dereference operator (->) in your GROQ query to expand the reference and get the full asset data.

The blog post example you're following uses Mux video inside a Portable Text field (that's what the text[] part is about), but it sounds like you have a direct video field on your document instead.

For a direct video field on your document type, your GROQ query should look like this:

*[_type == "video"]{
  ...,
  'video': video.asset->
}

This will dereference the asset and give you all the Mux asset data including playbackId, status, data, and other metadata that the sanity-mux-player component needs.

If you want to be more explicit about what data you're fetching, you can also write it like:

*[_type == "video"]{
  ...,
  video {
    asset-> {
      playbackId,
      status,
      data
    }
  }
}

The key is that -> operator after asset - that tells GROQ to follow the reference and return the actual asset document instead of just the reference object with _ref.

Once you have the playbackId in your query results, you can pass the asset data directly to the sanity-mux-player component's assetDocument prop, and it should handle the rest! The player component expects the full asset document with all the Mux metadata, which is why dereferencing is essential here.