Cosmos Db - insert if not exists

Dear Cosmos fellow members,

I am creating Azure Function (Python) with CosmosTrigger that:

• reads data from source_collection
• writes data to target_collection (only if document does not exist)

To achieve "insert if not exists" functionality I configured target_collection with unique key "name".

Example:

1. write to target_collection {"name": "John", "id": "1"} => OK
2. write to target_collection [{"name": "John", "id": "2"}, {"name": "Mary", "id": "3"}] => System.Private.CoreLib: Exception while executing function: Functions.CosmosTrigger. Microsoft.Azure.DocumentDB.Core: Entity with the specified id already exists in the system.

Unique key "name": "John" already exists in target_collection. So outdocs: func.Out[func.Document], outdocs.set() returns conflict 409 and "Mary" never gets written to target_collection.

Important: when I upload json with array of items from Data Explorer to target_collection, all conflicts return an error, but all items get processed. When I try to write it from Azure function, first conflict raises an error and remaining items never make it to target_collection.

My questions:

1. Is there a way to ignore raised errors and process whole array of items with func.Out[func.Document].set() ?
2. Alternatively could you please advise me what would be the best way to implement bulk "insert if not exist" behaviour in Cosmos?

def main(docs: func.DocumentList, outdocs: func.Out[func.Document]) -> str:
  compl_docs = func.DocumentList()

    compl_docs_dict = {
      "name": "John",
      "id": "2"
    }

    compl_docs.append(func.Document.from_dict(compl_docs_dict))

    compl_docs_dict = {
      "name": "Mary",
      "id": "3"
    }

    compl_docs.append(func.Document.from_dict(compl_docs_dict))

  outdocs.set(compl_docs)