Documentation for the App Store Connect API is poor, especially in comparison to the good documentation for the now-defunct XML-based "transporter" API. In the hope that it will be useful to others trying to do this in the future, here is how I was able to do a bulk update of my in-app purchases' prices using the API.
Step 1: get the IDs for the IAPs, if you don't already know them:
GET v1/apps/$app/inAppPurchasesV2
If you have a lot of IAPs, follow any links/next URL to get subsequent pages.
The ids are in data/id .
Step 2: get the current prices, if you don't already know them.
I believe you need to do a separate request for each IAP (right?).
GET v1/inAppPurchasePriceSchedules/$iap/manualPrices?include=inAppPurchasePricePoint,territory
The price and currency are in included/attributes/customerPrice and included/attributes/currency (I generally only have one "manual" price).
Step 3: look up the available price points:
GET v2/inAppPurchases/$iap/pricePoints?filter[territory]=$territory
The prices and IDs are in data/attributes/customerPrice and data/id.
Note this query takes the specific IAP ID. I don't know why. Are the price points specific to the IAPs? Can I reuse a price point ID that I've looked up for one IAP with another IAP for the same app?
Step 4: choose your new prices.
Step 5: Submit the new prices:
POST v1/inAppPurchasePriceSchedules
{
"data" : {
"relationships" : {
"baseTerritory" : {
"data" : {
"id" : "$territory",
"type" : "territories"
}
},
"inAppPurchase" : {
"data" : {
"id" : "$iap",
"type" : "inAppPurchases"
}
},
"manualPrices" : {
"data" : [
{
"id" : "$random_id",
"type" : "inAppPurchasePrices"
}
]
}
},
"type" : "inAppPurchasePriceSchedules"
},
"included" : [
{
"attributes" : {
"startDate" : null,
"endDate" : null
},
"id" : "$random_id",
"relationships" : {
"inAppPurchasePricePoint" : {
"data" : {
"id" : "$price_point_id",
"type" : "inAppPurchasePricePoints"
}
},
"inAppPurchaseV2" : {
"data" : {
"id" : "$iap",
"type" : "inAppPurchases"
}
}
},
"type" : "inAppPurchasePrices"
}
]
}
In that, $iap is the IAP ID from step 1, $territory is probably a three-letter string like GBR, $random_id is a random identifier that you generate (using the same value in the two places) (I'm not sure what the scope of this is; do I have to check that I don't accidentally send the same value in the future, or does it only exist while this submission is processed?), and $price_point_id is the ID for the price point from step 3.
I believe it is necessary to send a separate submission for each IAP (right?)
That example makes the change immediately (start and end dates are both null). Note that if you want to schedule a future change, you need to include both the current period and price and the future period and price in the submission.
I would like to thank @Efun whose posts in this thread: https://developer.apple.com/forums/thread/727159 helped a lot with understanding this.
