@azure/storage-blob - containerClient.listBlobsFlat() metadata property is empty

[diberry]

• Package Name: containerClient.listBlobsFlat()
• Package Version: 12.3.0
• Operating system: windows 10 internal
• nodejs
  • version: v10.15.3
• browser
  • name/version: Chrome Version 86.0.4240.198 (Official Build) (64-bit)
• typescript
  • version:3.7.5
• Is the bug related to documentation in
  • README.md
  • [ x] source code documentation
  • SDK API docs on https://docs.microsoft.com

Describe the bug
Metadata set on blob isn't returned as part of blobInfo in ListBlobsFlat. The Metadata property is returned, it just doesn't have the data.

To Reproduce
Steps to reproduce the behavior:

1. Create blob in FrontEnd React (create-react-app) with blobClient.uploadBrowserData(file, options);
2. Read returned results for url property which is the url for the blob
3. Set metadata on blob with url - blobClient.setMetadata({ urlAtCreation: blobClient.url });
4. Verify blob has metadata set with local Azure Storage Explorer
5. List blobs in container with containerClient.listBlobsFlat() - metadata property returned but is empty

Expected behavior
I expect if I set the metadata for a blob, and I can see the metadata in the Storage Explorer for that blob, then it is the same metadata that is returned with listBlobsFlat. Not sure why metadata is a string when I expect an object.

Screenshots
2 screenshots from react app debugging issue where metadata is returned as a string. 1 screenshot of storage explorer with metadata property I expect to see in code.

Additional context
I didn't add any additional security that would indicate I don't want metadata returned in the list.

[ljian3377]

You need to set the options.includeMetadata to true for List Blob to return metadata.

[diberry]

@ljian3377 I see that in the docs - thank you - missed that.

[diberry]

@ljian3377 When I set the metadata with a property name with a capitalization, why is the property name lowercased when returned via containerclient.listBlobsFlat? I can't find the docs that indicate this casing change.

`
// set metadata
const setMetadataResults = await blobClient.setMetadata({urlAtCreation:'test'});

// get blobs - urlAtCreation is empty
for await (const blob of container.containerClient.listBlobsFlat(options)) {
  const simplifiedBlob: AppBlobInfo = {
    name: blob.name,
    createdOn: blob.properties.createdOn,
    lastModified: blob.properties.lastModified,
    etag: blob.properties.etag,
    contentLength: blob.properties.contentLength,
    contentType: blob.properties.contentType,
    blobType: blob.properties.blobType,
    url: blob.metadata['urlAtCreation']
  };

  returnedBlobUrls.push(simplifiedBlob);
}

`

[jeremymeng]

When I set the metadata with a property name with a capitalization, why is the property name lowercased

This is unfortunate because the metadata is passed to the service via http header keys, and our http client node-fetch forces all lower cases for header key names. See related issues #4966, #8117.

We have some warnings in getProperties() and should probably add similar notes to the doc of setMetadata().

https://github.com/Azure/azure-sdk-for-js/blob/master/sdk/storage/storage-blob/src/Clients.ts#L1481

[diberry]

@jeremymeng Could there be a more general statement made such as..."All modern (track 2) libraries which use node-fetch and sends data via header key names, such as Storage Blob metadata, will have lowercased property names due to a node-fetch restriction."

Or just all libraries that depend on node-fetch can assume property names of JSON will be lowercased?

[jeremymeng]

"All modern (track 2) libraries which use node-fetch and sends data via header key names, such as Storage Blob metadata, will have lowercased property names due to a node-fetch restriction."

This. Only data send via http header key names are affected. Http header key values are working fine. Although Storage Blob metadata is the only impacted feature that I know so far.

[ljian3377]

@diberry What is your suggested follow-up for this issue?

Maybe

We have some warnings in getProperties() and should probably add similar notes to the doc of setMetadata().

[diberry]

Any storage methods that set or get headers that are lowercased need to have additional text - @jeremymeng text is fine.

All modern (track 2) libraries which use node-fetch and sends data via header key names, such as Storage Blob metadata, will have lowercased property names due to a node-fetch restriction.

[github-actions]

Hi @diberry, we deeply appreciate your input into this project. Regrettably, this issue has remained inactive for over 2 years, leading us to the decision to close it. We've implemented this policy to maintain the relevance of our issue queue and facilitate easier navigation for new contributors. If you still believe this topic requires attention, please feel free to create a new issue, referencing this one. Thank you for your understanding and ongoing support.