Object metadata does not update if a key is removed

[KeithKeithDev]

Using version: 1.47.6

I create an object with the initial custom metadata:

{foo=bar, baz=qux}

When trying to update the object's metadata with the following map (e.g. the 'foo' entry is now removed)
{baz=qux}

using the following code (as per the google gcs documentation here):

val updated = blob.toBuilder.setMetadata(metadata.asJava).build().update()
println(s"Updated metadata ${updated.getMetadata.asScala}")

The following is logged and we can see that the foo entry is still there.
Updated metadata Map(baz -> qux, foo -> bar)

However, if I update the object by changing the mapping of a single entry, so I update with:
{baz=blah}

Then I can see that the object's metadata is now updated to have just the 1 key and the foo mapping is gone, as expected:
Updated metadata Map(baz -> blah)

Is this a bug?

[fsouza]

@KeithKeithDev thanks for reporting! This is definitely unexpected.

[KeithKeithDev]

@fsouza actually, I may have been making the wrong API call. To delete a key, you need to set a mapping to null for that key as per https://cloud.google.com/storage/docs/json_api#patch. So in reality, I should have called setMetadata with foo -> null.

However, I see another potential issue.

1. I create an object with initial metadata mapping "foo" -> "bar"
2. I run the curl command to see the object in fake-gcs-server: curl http://localhost:55007/storage/v1/b/my-bucket/o. I can see "metadata":{"foo":"bar"}
3. In my code, I call val updated = blob.toBuilder.setMetadata(metadata.asJava).build().update() with a new metadata mapping of "baz" -> "qux".
4. When I run the same curl command against fake-gcs-server again, to see the object's metadata, curl http://localhost:55007/storage/v1/b/my-bucket/o. I can see "metadata":{"baz":"qux"}

It looks like the original metadata is wiped. https://cloud.google.com/storage/docs/json_api#patch. Can you reproduce this and confirm if it's an issue?

[KeithKeithDev]

@fsouza - also, another potential issue.

When deleting a metadata item, it appears that the keys still exist, although the mapped value is "null". For example, if I call:

val toDelete: Map[String, String] = Map("foo" -> null)
val updated = blob.toBuilder.setMetadata(toDelete.asJava).build().update()

If I then call updated.getMetadata, I see: Map(foo -> ). If I do the same test against GCS, I can see it deletes the 'foo' metadata item.