Error on clusters.py when shards: null

[jfrancoa]

Trying to execute a test case, a bug in the weaviate/collections/classes/cluster.py file was found. Weaviate, when no shards exist for a specific node returns shards: null when that node does not have any active shard, however the code expects a list, not a null value:

curl "http://127.0.0.1:8080/v1/nodes?output=verbose" | jq
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   713  100   713    0     0  72926      0 --:--:-- --:--:-- --:--:-- 79222
{
  "nodes": [
    {
      "batchStats": {
        "queueLength": 0,
        "ratePerSecond": 0
      },
      "gitHash": "d58d616",
      "name": "weaviate-0",
      "shards": null,
      "stats": {
        "objectCount": 0,
        "shardCount": 0
      },
      "status": "HEALTHY",
      "version": "1.24.2"
    },
    {
      "batchStats": {
        "queueLength": 0,
        "ratePerSecond": 0
      },
      "gitHash": "d58d616",
      "name": "weaviate-1",
      "shards": [
        {
          "class": "Multitenant_ugw5eogq",
          "compressed": false,
          "loaded": true,
          "name": "tenant0",
          "objectCount": 0,
          "vectorIndexingStatus": "READY",
          "vectorQueueLength": 0
        }
      ],
      "stats": {
        "objectCount": 0,
        "shardCount": 1
      },
      "status": "HEALTHY",
      "version": "1.24.2"
    },
    {
      "batchStats": {
        "queueLength": 0,
        "ratePerSecond": 0
      },
      "gitHash": "d58d616",
      "name": "weaviate-2",
      "shards": null,
      "stats": {
        "objectCount": 0,
        "shardCount": 0
      },
      "status": "HEALTHY",
      "version": "1.24.2"
    }
  ]
}

When trying to obtain the verbose cluster's information, the python-client fails with:

    @pytest.mark.parametrize("number_of_tenants", [1, 100, 1000])
    def test_multitenant_creation(multitenant_class, number_of_tenants):
        collection, client = multitenant_class
        collection.tenants.create([Tenant(name=f"tenant{i}") for i in range(number_of_tenants)])
        count = 0
>       for node in client.cluster.nodes(collection.name, output="verbose"):

tests/core/multitenant_test.py:40: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
.venv/lib/python3.10/site-packages/weaviate/collections/cluster.py:83: in nodes
    return _ConvertFromREST.nodes_verbose(nodes)
.venv/lib/python3.10/site-packages/weaviate/collections/classes/cluster.py:45: in nodes_verbose
    return [
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

.0 = <list_iterator object at 0x10cbd3f40>

    return [
        Node(
            git_hash=node["gitHash"],
            name=node["name"],
            shards=(
>               [
                    Shard(
                        collection=shard["class"],
                        name=shard["name"],
                        node=node["name"],
                        object_count=shard["objectCount"],
                    )
                    for shard in cast(List[ShardREST], node["shards"])
                ]
                if "shards" in node
                else []
            ),
            stats=(
                Stats(
                    object_count=node["stats"]["objectCount"],
                    shard_count=node["stats"]["shardCount"],
                )
                if "stats" in node
                else []
            ),
            status=node["status"],
            version=node["version"],
        )
        for node in nodes
    ]
E   TypeError: 'NoneType' object is not iterable

A possible solution consists on adding a condition to the if, that if node["shards"] is None to also return []:

if "shards" in node and node["shards"] is not None
else []

I will submit a fix for the issue.