unmarshal of imp.ext.{bidder} fails in dealTier flow after addition of tid field in impression

[AvinashKapre]

In the PR: #2412 a mandatory field tid was introduced at imp.ext due to which ReadDealTiersFromImp() function fails to unmarshal the ext for usecase imp.ext.{bidder}

i.e: This sample input fails to unmarshal into type impExt

"imp": [
    {
        "ext": {
            "appnexus": {
                "dealtier": {
                    "prefix": "apnx",
                    "mindealtier": 4
                }
            }
            "tid": "1234"
        }
    }
]

// for imp.ext.{bidder}
var impExt map[string]struct {
		DealTier *DealTier `json:"dealTier"`
}

Current behaviour: ReadDealTiersFromImp() returns without dealtier specified in the new location imp.ext.prebid.{bidder}.
Expected behaviour: As imp.ext.{bidder} is deprecated, we should ignore the unmarhal error for it and proceed to check for dealtier in the new location imp.ext.prebid.{bidder}.

Shall I go ahead and submit a fix for the same do we want to support the new field tid for deprecated field as well?. I'll update the code accordingly.

[bsardo]

Hi @AvinashKapre,

You're correct that there is a problem here as I was able to reproduce the issue. The deal tiers are not being captured from the request due to the presence of the tid field or any other primitive type in imp.ext.

I'll push up a fix that removes the logic that looks for deal tiers at imp.ext.BIDDER since all bidder information at imp.ext.BIDDER is migrated to imp.ext.prebid.bidder.BIDDER upstream during request validation in validateImpExt before ReadDealTiersFromImp is executed.