Azure CosmosDB - Partial Document Update (Patch) on Complex Structures

Question

I'm trying to use the Partial Document Update (Patch API) to update a child object in my document, but I'm running into trouble. I found this Stack Overflow question which is the same question that I have. However, the accepted answer resolves the problem by referring to an object in an array by index. I don't believe that I have the luxury of being able to do that. So, to use the same example document as the other question...

{
    "id": "SalesOrder2",
    "ponumber": "PO15428132599",
    "OrderDate": "2005-07-01T00:00:00",
    "DueDate": "2005-07-13T00:00:00",
    "ShippedDate": "2005-07-08T00:00:00",
    "AccountNumber": "Account2",
    "SubTotal": 6107.082,
    "TaxAmt": 586.1203,
    "Freight": 183.1626,
    "TotalDue": 4893.3929,
    "DiscountAmt": 1982.872,
    "Items": [
        {
            "Id": 1,
            "OrderQty": 3,
            "ProductCode": "A-123",
            "ProductName": "Product 1",
            "CurrencySymbol": "$",
            "CurrencyCode": "USD",
            "UnitPrice": 17.1,
            "LineTotal": 5.7
        },
        {
            "Id": 2,
            "OrderQty": 2,
            "ProductCode": "A-456",
            "ProductName": "Product 2",
            "CurrencySymbol": "$",
            "CurrencyCode": "USD",
            "UnitPrice": 10,
            "LineTotal": 20
        }
    ],    
    "_rid": "BsMkAMc43s4CAAAAAAAAAA==",
    "_self": "dbs/BsMkAA==/colls/BsMkAMc43s4=/docs/BsMkAMc43s4CAAAAAAAAAA==/",
    "_etag": "\"00000000-0000-0000-e136-0dbec04601d7\"",
    "_attachments": "attachments/",
    "_ts": 1637760030
}

I have no guarantee that the item in the Items array with an Id of 1 would be in position 0 of the array. Similarly, the item with an Id of 2 is not guaranteed to be in position 1. Therefore I believe that I need to use the FilterPredicate parameter of the Patch API to filter my results. But when I attempt to do that, I keep getting the following exception:

Microsoft.Azure.Cosmos.CosmosException : Response status code does not indicate success: PreconditionFailed (412); Substatus: 1110; ActivityId: dbd258ae-0a0a-4a9b-8c25-1d36e137b7c5; Reason: ();

Any assistance you could provide on how to accomplish this would be appreciated.

Oecology

Answer 1

As i answered in the attached link, Patch requires the user to pass the specific index of the object needs to be updated. We are working on enabling this particular feature in the coming months, However as an alternative, you should look at Conditional Patch

Code will be something like this,

response = patch(operation, Condition(check if item exists))

if(response == fail/precondition failed)
{
PatchOperation operation = PatchOperation.Add("/Items", [{"Id" : "P-1", "Description" : "My Product"}]);
}

Gastrocnemius

Thank you for the response. I actually did try the filterPredicate. In fact, my error message in the question shows "precondition failed" from one of my attempts to filter the results that way. What I've concluded is that the filterPredicate does not filter the document in any way, instead it simple checks to see if the filter condition is met and either allows the patch operation to continue or not. – Oecology

@Sajeetharan, any news on this yet? – Danialdaniala