Merge pull request #590 from oasisprotocol/pro-wh/bugfix/nftburn

runtime: add explicit PossibleNFT.Burned field

analyzer/queries/queries.go

@@ -722,8 +722,8 @@ var (
 
 	RuntimeEVMNFTUpdateTransfer = `
     UPDATE chain.evm_nfts SET
-      owner = $4,
-      num_transfers = num_transfers + $5
+      num_transfers = num_transfers + $4,
+      owner = $5
     WHERE
       runtime = $1 AND
       token_address = $2 AND

analyzer/runtime/extract.go

@@ -121,12 +121,14 @@ type NFTKey struct {
 }
 
 type PossibleNFT struct {
-	// NewOwner has the latest owner if .NumTransfers is more than zero. If
-	// the last transfer burned this NFT instance, then it's the empty string.
-	NewOwner apiTypes.Address
 	// NumTransfers is how many times we saw it transferred. If it's more than
-	// zero, the new owner is in .NewOwner.
+	// zero, Burned or NewOwner will be set.
 	NumTransfers int
+	// Burned is true if NumTransfers is more than zero and the NFT instance
+	// was burned.
+	Burned bool
+	// NewOwner has the latest owner if NumTransfers is more than zero.
+	NewOwner apiTypes.Address
 }
 
 type BlockData struct {
@@ -271,9 +273,10 @@ func registerNFTExist(nftChanges map[NFTKey]*PossibleNFT, contractAddr apiTypes.
 	findPossibleNFT(nftChanges, contractAddr, tokenID)
 }
 
-func registerNFTTransfer(nftChanges map[NFTKey]*PossibleNFT, contractAddr apiTypes.Address, tokenID *big.Int, newOwner apiTypes.Address) {
+func registerNFTTransfer(nftChanges map[NFTKey]*PossibleNFT, contractAddr apiTypes.Address, tokenID *big.Int, burned bool, newOwner apiTypes.Address) {
 	possibleNFT := findPossibleNFT(nftChanges, contractAddr, tokenID)
 	possibleNFT.NumTransfers++
+	possibleNFT.Burned = burned
 	possibleNFT.NewOwner = newOwner
 }
 
@@ -1006,7 +1009,7 @@ func extractEvents(blockData *BlockData, relatedAccountAddresses map[apiTypes.Ad
 					}
 					registerNFTExist(blockData.PossibleNFTs, eventAddr, tokenID)
 					// Mints, burns, and zero-value transfers all count as transfers.
-					registerNFTTransfer(blockData.PossibleNFTs, eventAddr, tokenID, toAddr)
+					registerNFTTransfer(blockData.PossibleNFTs, eventAddr, tokenID, toZero, toAddr)
 					eventData.EvmLogName = evmabi.ERC721.Events["Transfer"].Name
 					eventData.EvmLogSignature = ethCommon.BytesToHash(event.Topics[0])
 					eventData.EvmLogParams = []*apiTypes.EvmEventParam{

analyzer/runtime/runtime.go

@@ -404,16 +404,16 @@ func (m *processor) queueDbUpdates(batch *storage.QueryBatch, data *BlockData) {
 		)
 		if possibleNFT.NumTransfers > 0 {
 			var newOwner *apiTypes.Address
-			if possibleNFT.NewOwner != "" {
+			if !possibleNFT.Burned {
 				newOwner = &possibleNFT.NewOwner
 			}
 			batch.Queue(
 				queries.RuntimeEVMNFTUpdateTransfer,
 				m.runtime,
 				key.TokenAddress,
 				key.TokenID,
-				newOwner,
 				possibleNFT.NumTransfers,
+				newOwner,
 			)
 		}
 	}