切换到 graphql 15.5.1 后返回空数组导致“无法返回空值”错误

如何解决切换到 graphql 15.5.1 后返回空数组导致“无法返回空值”错误

编辑：您可以跳到最后查看代码和框错误的简化示例

我正在将我的 apollo 项目升级到新版本的 graphql，但出现了一个奇怪的错误。在 google 上找不到与此场景匹配的任何结果。当我尝试返回具有不可为空字段（包括天）的 ObjectTypes DrivingActivitiesDailySummaryType 的空数组时，它会抛出“无法为不可为空的字段 DrivingActivitiesDailySummaryType.day 返回空值。”。这在 14.7.0 版中按预期工作。这里发生了什么事？如何避免？我认为正常的行为是允许空数组，而我在更改日志中找不到任何表明此类更改的内容。

我的解析器目前只返回一个硬编码值用于测试：

@Query(() => DrivingActivityPayload)
    public async totalDrivingActivity(
        @Ctx("user") userContext: UserContext,@Args() input: DrivingActivitiesQueryInput
    ): Promise<DrivingActivityPayload> {
        return {
            totalSummary: { speed: 1,activities: 1,duration: 1,distance: 1 },dailySummaries: [],monthlySummaries: [],}
    }

我的负载定义：

@ObjectType()
export class DrivingActivityPayload {
    @Field(() => DrivingActivitiesTotalSummaryType)
    public totalSummary: DrivingActivitiesTotalSummaryType

    @Field(() => DrivingActivitiesDailySummaryType)
    public dailySummaries: DrivingActivitiesDailySummaryType[]

    @Field(() => DrivingActivitiesMonthlySummaryType)
    public monthlySummaries: DrivingActivitiesMonthlySummaryType[]

    constructor(
        totalSummary: DrivingActivitiesTotalSummaryType,dailySummaries: DrivingActivitiesDailySummaryType[],monthlySummaries: DrivingActivitiesMonthlySummaryType[]
    ) {
        this.totalSummary = new DrivingActivitiesTotalSummaryType(totalSummary)
        this.dailySummaries = dailySummaries.map(summary => new DrivingActivitiesDailySummaryType(summary))
        this.monthlySummaries = monthlySummaries.map(summary => new DrivingActivitiesMonthlySummaryType(summary))
    }
}

GraphQL 错误：

  "errors": [
    {
      "message": "Cannot return null for non-nullable field DrivingActivitiesDailySummaryType.day.","locations": [
        {
          "line": 18,"column": 7
        }
      ],"path": [
        "totalDrivingActivity","dailySummaries","day"
      ],"extensions": {
        "code": "INTERNAL_SERVER_ERROR","exception": {
          "stacktrace": [
            "Error: Cannot return null for non-nullable field DrivingActivitiesDailySummaryType.day.","    at completeValue ([PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:559:13)","    at resolveField ([PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:472:19)","    at executeFields ([PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:292:18)","    at collectAndExecuteSubfields ([PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:748:10)","    at completeObjectValue ([PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:738:10)","    at completeValue ([PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:590:12)","    at completeValue ([PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:556:21)","    at [PROJECT-FOLDER]/node_modules/graphql/execution/execute.js:469:16","    at processticksAndRejections (node:internal/process/task_queues:96:5)","    at async Promise.all (index 0)"
          ]
        }
      }
    }
  ],"data": null
}

DrivingActivitiesDailySummaryType 定义（尽管这无关紧要）：

@ObjectType()
export class DrivingActivitiesDailySummaryType {
    @Field(() => Date)
    public day: Date

    @Field()
    public distance: number

    @Field()
    public activities: number

    constructor(summary: DrivingActivitiesDailySummaryType) {
        this.day = summary.day
        this.activities = summary.activities
        this.distance = summary.distance
    }
}

编辑：这是一个带有重现错误的沙箱链接： https://codesandbox.io/s/heuristic-jepsen-5frr3?file=/package.json （我不知道如何更改默认终端行为，因此您必须打开一个带有“+”图标的新终端并运行“npm start”）当使用提供的 package.json（新版本）时，错误重现，当你用 package-old.json（旧版本的 graphql 和 type-graphql）切换 package.json 的内容时，没有错误。

EDIT2：您可能需要在代码和框链接中添加“/graphql”才能使其工作

解决方法

您应该将每日和每月摘要定义为数组：

@Field(() => [DrivingActivitiesDailySummaryType])
public dailySummaries: DrivingActivitiesDailySummaryType[]

@Field(() => [DrivingActivitiesMonthlySummaryType])
public monthlySummaries: DrivingActivitiesMonthlySummaryType[]