node.js - 在嵌套数组中查找和删除文档

Question

我正在努力删除 mongoDB 中嵌套数组中的元素。

假设我有这个架构:

var question = new Schema({
  problem: {
    type: String,
    required: true
  },
  multipleChoices: [{
    type: String,
    required: true
  }],
  correctAnswer: {
    type: Number,
    required: true
  }
});

var testCategorySchema = new Schema({
  category: {
    type: String,
    required: true
  },
  tests: [{
    version: {
      type: String,
      required: true
    },
    questions: [question]
  }]
});

例如，我有这样一个模式的实例:

{
  category: "Math",
  tests: [
    {
      _id : ObjectId("580859310a0d4b40ac1c6034"),
      version: "1A",
      questions: [
         {
           problem: "blablabla",
           multiplechoices: [
            "bla bla", "blb blb", "blc blc"
          ],
           correctAnswer: 1
         },
         {
           problem: "blibliblibli",
           multiplechoices: [
            "bla bla", "blb blb", "blc blc"
          ]
           correctAnswer: 1
         }
      ]
    },
    {
      _id : ObjectId("580859310a0d4r40ax1c5034"),
      version: "1B",
      questions: [
         {
           problem: "auauauauau",
           multiplechoices: [
            "bla bla", "blb blb", "blc blc"
          ]
           correctAnswer: 1
         },
         {
           problem: "blibliblibli",
           multiplechoices: [
            "bla bla", "blb blb", "blc blc"
          ]
           correctAnswer: 1
         }
      ]
    }
  ]
}

例如，如何使用 mongooseJS 删除问题:类别数学和版本 1A 中的“blablabla”？

我已经使用此代码删除了数学类别和版本 1A 中的问题:

TestCategory
    .findOne(
      {
        category: req.params.testCategory,
        'tests.version': req.params.testVersion
      },
      {
        'tests.version.$': 1
      }
    )
    .then(function(testVersion) {
      res.send(testVersion);
    })
    .catch(function(err) {
      console.log(err);
      next(err);
    });

例如我搜索数学类别和版本 1A，该代码的结果是这样的:

_id: "580859190a0d4b40ac1c6033",
tests: [
    {
      _id : ObjectId("580859310a0d4b40ac1c6034"),
      version: "1A",
      questions: [
         {
           problem: "blablabla",
           multiplechoices: [
            "bla bla", "blb blb", "blc blc"
          ],
           correctAnswer: 1
         },
         {
           problem: "blibliblibli",
           multiplechoices: [
            "bla bla", "blb blb", "blc blc"
          ]
           correctAnswer: 1
         }
      ]
    }
]

结果已经过过滤，所以只显示版本1A(虽然仍显示categoryId)。现在我很困惑如何以正确和好的方式删除问题。

Answer 1

您需要将 update 与位置运算符 $ 一起使用为了更新正确的测试然后使用 $pull删除问题:

TestCategory.update(
    {
        category: 'Math',
        'tests.version': '1A'
    },
    {
        $pull: {
            'tests.$.questions': { problem: 'blablabla' }
        }
    }
)