Upsert of a document (a dictionary) with null values doesn't insert those null values.

[rogerk-unifysquare]

When writing a dictionary through the Update (with the document as Upsert; see below), all the values in the dictionary are not serialized and therefore not stored/updated on the document.

Consider:

Dictionary<string, string> test = new Dictionary<string, string>() {
{ "abc", null },
{ "def", "ghi" },
};

IUpdateResponse resp = client.Update<Dictionary<string, string>>(
ud => ud
.Type(DocumentType)
.Id("test")
.Doc(test)
.DocAsUpsert(true));

This results in the following request body:
{
"doc_as_upsert": true,
"doc": {
"def": "ghi"
}
}

i.e. the abc=null entry is missing. Also, setting the NullValueHandling property of the JsonSerializerSettings (through the SetJsonSerializerSettingsModifier method of the ConnectionSettings) doesn't fix this problem since it appears that the settings are only applied to the high-level request envelope, but not to the document. This basically seems to make it impossible to clear properties which were previsouly set without using scripts ...

[gmarz]

Hey @rogerk-unifysquare

While I was able to reproduce this and agree that the serialization of null values on dictionaries should behave the same as they do on object, I just want to clarify your expectations here. Are you trying to remove the field from the document or replace their values with null? There's no way to remove fields using a partial doc in Elasticsearch- a script is the only way to accomplish this.

[rogerk-unifysquare]

Yes, I am just trying to replace the field's value with null.

[gmarz]

@rogerk-unifysquare I just pushed the above fix. Thanks for reporting this!