javascript - 在 Node js 中使用 Promise 时，函数无法正常工作

Question

我有这样的路线:

router.get('/:projectid/, (req, res) => {
    testCase.getTestCaseDetail(req.params.projectid, req.params.testcaseid, req.params.snapshotId).then(testcaseData => {
      res.render('testCaseService', {
        title: 'Page',
        testcase: testcaseData,
        layout: 'project_layout',
      });
    });
  });

在处理函数中，我有 getTestCaseDetail 函数:

function getTestCaseDetail(projectId, id, snapshotId) {
  let testCaseId = parseInt(id);
  return new Promise(((resolve, reject) => {
    return testCaseSchema.aggregate([
      { $match: { 'projectId': projectId, 'testCaseId': testCaseId } },
      {
        $lookup: {
          from: snapshotInfoSchema.collection.collectionName,
          localField: testCaseObj.SERVICE_ID,
          foreignField: 'artifacts.id',
          as: 'services',
        },
      },
      { $unwind: '$services' },
      {
        $match: {
          'services.snapshot.id': snapshotId,
        }
      }
    ]).then(testCaseResult => {
      resolve(addTestCasesV2(testCaseResult, snapshotId));
    })
      .catch(err => {
        reject(err);
      })
  }));
}

和addTestCasesV2函数

const addTestCasesV2 = function (testcases, snapshotId) {
  const result = [];
  let serviceTypeMapping;
  let serviceName;
  let testCase = {
    id: '',
    testCaseId: '',
    name: '',
    serviceName: '',
    serviceType: '',
    modifiedAt: '',
    testScripts: '',
    snapshotId: '',
    services: '',
    inputs: [],
    outputs: [],
  };
  let promiseInputResults, promiseOutputResults;
  const testcasesList = lodash.map(testcases, (tc) => {
    const artifacts = lodash.map(tc.services.artifacts, (art) => {
      if (art.id === tc.service_id) {
        serviceTypeMapping = art.processType.serviceTypeName;
        serviceName = art.name;
        if (!commonUtil.isUndefined(art.processParameters)) {
          if (!commonUtil.isUndefined(art.processParameters.input)) {
            promiseInputResults = lodash.map(art.processParameters.input, (ip) => {
              let classId = commonUtil.getArtifactId(ip.classId);
              return objectType.getObjectTypeByClassId(snapshotId, classId)
            });
          }

          if (!commonUtil.isUndefined(art.processParameters.output)) {
            promiseOutputResults = lodash.map(art.processParameters.output, (ip) => {
              let classId = commonUtil.getArtifactId(ip.classId);
              return objectType.getObjectTypeByClassId(snapshotId, classId)
            });
          }
        }
        testCase.id = tc.testCaseId;
        testCase.testCaseId = tc.testCaseId;
        testCase.name = tc.name;
        testCase.serviceName = serviceName;
        testCase.serviceType = serviceTypeMapping;
        testCase.modifiedAt = tc.modifiedAt;
        testCase.testScripts = tc.testScripts;
        testCase.snapshotId = snapshotId;
        testCase.services = tc.services;

        Promise.all(promiseInputResults).then(inputItems => {
          return testCase.inputs = inputItems;
        });

        Promise.all(promiseOutputResults).then(outputItems => {
          return testCase.outputs = outputItems;
        });

      }
    });
  });
  return testCase;
};

输入/输出是一个项目列表，如下所示:输入:[ { 名称:“测试1”， 类型:“字符串” }, { 名称:“测试2”， 类型:“数字” }, ]

我的 Promise 生命周期有问题，这是当前流程1. 路线2. 函数 getTestCaseDetail3. 解析(addTestCasesV2(testCaseResult, snapshotId));4. addTestCasesV2 ==> 返回 testCase 但不执行 2 个promise.all 函数5. 解析(addTestCasesV2(testCaseResult, snapshotId));6. 路线7. 返回2个promise.all函数8. 结束于 return testCase.outputs = outputItems;

请查看图片以了解更多详细流量(白色数字是当前流量，橙色数字是我期望的流量)

请给我建议。非常感谢。

Answer 1

您的代码似乎不正确。如果 testcases 是一个包含多个项目的数组，则您的 lodash.map 回调将被调用 testcases.length 次。每次都会覆盖之前回调中分配的 testCase.id。

无论如何，我已经更正了您的代码部分，使其按照您想要的运行顺序。我已经在不同的地方记录了 ==step== 来寻求您的帮助。

第一个功能:

function getTestCaseDetail(projectId, id, snapshotId) {
    let testCaseId = parseInt(id);
    return new Promise(((resolve, reject) => {
        return testCaseSchema.aggregate([
            { $match: { 'projectId': projectId, 'testCaseId': testCaseId } },
            {
                $lookup: {
                    from: snapshotInfoSchema.collection.collectionName,
                    localField: testCaseObj.SERVICE_ID,
                    foreignField: 'artifacts.id',
                    as: 'services',
                },
            },
            { $unwind: '$services' },
            {
                $match: {
                    'services.snapshot.id': snapshotId,
                }
            }
        ]).then(testCaseResult => {
            console.log('=======STEP 1=======');
            resolve(addTestCasesV2(testCaseResult, snapshotId));//=======STEP 2=======
            console.log('=======STEP 5=======')

        })
            .catch(err => {
                reject(err);
            })
    }));
}

第二个函数

const addTestCasesV2 = function (testcases, snapshotId) {
    console.log('=======STEP 2=======')
    const result = [];
    let serviceTypeMapping;
    let serviceName;
    let testCase = {
        id: '',
        testCaseId: '',
        name: '',
        serviceName: '',
        serviceType: '',
        modifiedAt: '',
        testScripts: '',
        snapshotId: '',
        services: '',
        inputs: [],
        outputs: [],
    };
    let promiseInputResults, promiseOutputResults;

    return Promise.resolve()
        .then(()=>{
            console.log('=======STEP 3=======');
            const testcasesList = lodash.map(testcases, (tc) => {
                const artifacts = lodash.map(tc.services.artifacts, (art) => {
                    if (art.id === tc.service_id) {
                        serviceTypeMapping = art.processType.serviceTypeName;
                        serviceName = art.name;
                        if (!commonUtil.isUndefined(art.processParameters)) {
                            if (!commonUtil.isUndefined(art.processParameters.input)) {
                                promiseInputResults = lodash.map(art.processParameters.input, (ip) => {
                                    let classId = commonUtil.getArtifactId(ip.classId);
                                    return objectType.getObjectTypeByClassId(snapshotId, classId)
                                });
                            }

                            if (!commonUtil.isUndefined(art.processParameters.output)) {
                                promiseOutputResults = lodash.map(art.processParameters.output, (ip) => {
                                    let classId = commonUtil.getArtifactId(ip.classId);
                                    return objectType.getObjectTypeByClassId(snapshotId, classId)
                                });
                            }
                        }
                        testCase.id = tc.testCaseId;
                        testCase.testCaseId = tc.testCaseId;
                        testCase.name = tc.name;
                        testCase.serviceName = serviceName;
                        testCase.serviceType = serviceTypeMapping;
                        testCase.modifiedAt = tc.modifiedAt;
                        testCase.testScripts = tc.testScripts;
                        testCase.snapshotId = snapshotId;
                        testCase.services = tc.services;


                        /*=======FOLLOWING IS NOT REQUIRED=======*/
                        // Promise.all([promiseOutputResults]).then(outputItems => {
                        //     return testCase.outputs = outputItems;
                        // });

                    }
                });
            });
            return Promise.all([promiseInputResults,promiseOutputResults]);
        })
        .then(inputItems => {//array of resolved values
            console.log('=======STEP 4=======');
            testCase.inputs = inputItems[0];
            testCase.outputs = inputItems[1];
            return testCase;
        })
};

现在您可以使用以下命令从第一个函数中提取测试用例:

getTestCaseDetail(myProjectId, id, mySnapshotId)
    .then(testCase=>console.log(testCase))

JSfiddle供您理解。