Can't Set Value to Null using Patch Operation

[brandonsmith86]

We are continuously addressing and improving the SDK, if possible, make sure the problem persist in the latest SDK version.

Describe the bug
When using PatchOperation.Replace, I am unable to set value to null. I have tried both null and new JProperty(propName, null).Value. The latter was attempted due to recommendation in #2931.

To Reproduce
This is the code used to create PatchOperation: PatchOperation.Replace($"/{cosmosPropName}", propValue ?? createNullValue(cosmosPropName)).

propValue is type object?. createNullValue() creates the JProperty mentioned in the description.

Expected behavior
I would expect the property to be set to null value. Below example assumes description property is being set to null:

{
 "id": "adfda-asdgasd-adsfasdf",
  "partition_key": "aigeqwg-iuiou-qryqer",
  "description": null
}

Actual behavior
Description property is unchanged.

Environment summary
SDK Version: 3.32.0
OS Version: Windows 10

Additional context
Nothing additional to add.

[aavasthy]

@brandonsmith86 I am able to replace the property value with null using the latest SDK version https://www.nuget.org/packages/Microsoft.Azure.Cosmos. You would need to explicitly specify the type argument for 'Replace' method.

Code example:

ItemResponse<Product> response = await container.PatchItemAsync<Product>(
           id: newItem.id,
           partitionKey: new PartitionKey(newItem.category),
           patchOperations: new[] { PatchOperation.Replace<string>($"/{cosmosPropName}", null) });

Please let me know if you run into any issues with this.

[brandonsmith86]

Hi @aavasthy. Thank you for spending the time to reproduce. Do you think my problem is version, or lack of generic type? With my current implementation, I would not be able to supply type as I'm using reflection to get the value, which returns object? type.

Edit: I suppose I can do something like this. I'll check tomorrow if this resolves it (in addition to updating to latest version).

patchOperations.Add(propValue == null // use generic version of PatchOperation.Replace if value is null
  ? PatchOperation.Replace<string?>($"/{cosmosPropName}", null)
  : PatchOperation.Replace($"/{cosmosPropName}", propValue));

[aavasthy]

@brandonsmith86 Please try with the latest version because I don't see SDK Version: 3.32.0 in here https://www.nuget.org/packages/Microsoft.Azure.Cosmos.
I was able to update the property name even with this code

string val = null;
ItemResponse<Product> response = await container.PatchItemAsync<Product>(
    id: newItem.id,
    partitionKey: new PartitionKey(newItem.category),
    patchOperations: new[] { PatchOperation.Replace($"/propertyName", val) });

[brandonsmith86]

@aavasthy Decided to give it a try today. The code that I posted above did not clear out the property. Very curious...

[brandonsmith86]

@aavasthy Found an issue in my logic. Updating versions does resolve it. Thank you!

[brandonsmith86]

Closing this issue since updating fixed my issue.