调用钩子时出现意外错误:不可为null的字段缺少值

Question

我正试图按照这里的示例(具有更高性能的方法的示例(为Graph Protocol构建一个子图。在使用测试工具matchstick作为^0.5.0编译Graph协议项目的过程中，我得到了以下错误：

Igniting tests
nft-lottery
--------------------------------------------------
Enter the NFT Lottery:
thread 'main' panicked at '🆘 Unexpected error upon calling hook: Missing value for non-nullable field 'player' for an entity of type 'PlayerToLottery'.
wasm backtrace:
0: 0x331a - <unknown>!src/nft-lottery/handleNftLotteryEnter;
1: 0x3807 - <unknown>!start:tests/nft-lottery.test~anonymous|0~anonymous|0

有人能帮我吗？

这是我的/schema.graphql

type NftLottery @entity {
id: ID!
open: BigInt!
close: BigInt!
prize: BigInt!
players: [PlayerToLottery!]! @derivedFrom(field: "lottery")
requestId: BigInt
updatedAtTimestamp: BigInt
}
type Player @entity {
id: ID! # address
lotteries: [PlayerToLottery!]! @derivedFrom(field: "player")
}
type PlayerToLottery @entity {
id: ID! # Set playerAddress.toHexString() + lotteryId.toHexString()
player: Player!
lottery: NftLottery!
}
# events
type NftLotteryEnter @entity {
id: ID! # Set lotteryCounter + playerAddress
lotteryCounter: BigInt!
player: Bytes!
numberOfEntrances: [BigInt!]!
updatedAtTimestamp: BigInt
}

这是我的/src/mapping.ts

function getIdFromEventAddressInt(par2: Address, par1: BigInt): string {
return par1.toHexString() + par2.toHexString()
}
export function handleNftLotteryEnter(event: NftLotteryEnterEvent): void {
/* if a PlayerToLottery does not exists, create it */
const playerLotteryId = getIdFromEventAddressInt(event.params.player, event.params.lotteryCounter)
let playerToLottery = PlayerToLottery.load(playerLotteryId)
if (!playerToLottery) {
playerToLottery = new PlayerToLottery(playerLotteryId)
playerToLottery.save()
}
/* if a player does not exist, create them */
const playerId = event.params.player.toHexString()
let player = Player.load(playerId)
if (!player) {
player = new Player(playerId)
player.save()
}
/* if a lottery does not exist, create it */ 
const itemId = event.params.lotteryCounter.toHexString()
let nftLottery = NftLottery.load(itemId)
if (!nftLottery) {
nftLottery = new NftLottery(itemId)
nftLottery.open = event.block.timestamp
nftLottery.close = BigInt.fromString("000000000000")
nftLottery.prize = BigInt.fromString(event.params.entranceFee.toString())
nftLottery.players = new Array<string>()
}
// update lottery data
nftLottery.prize.plus(event.params.entranceFee)
// update players
let arrPlayers = nftLottery.players
arrPlayers.push(event.params.player.toHexString())
nftLottery.players = arrPlayers
nftLottery.updatedAtTimestamp = event.block.timestamp
nftLottery.save()
}

Answer 1

实体PlayerToLottery在保存之前需要分配值：

/* if a PlayerToLottery does not exists, create it */
const playerLotteryId = getIdFromEventAddressInt(event.params.player, event.params.lotteryCounter)
let playerToLottery = PlayerToLottery.load(playerLotteryId)
if (!playerToLottery) {
playerToLottery = new PlayerToLottery(playerLotteryId)
playerToLottery.player = event.params.player.toHexString()
playerToLottery.lottery = event.params.lotteryCounter.toHexString()
playerToLottery.save()
}

这要归功于图形不和谐单元测试中的Maks#3349。