同一架構中的引用字段

Question

我有一個架構

const mySchema = new Schema({
  limit: Number,
  currentlyAdded: Number
});

我希望currentlyAdded最多為limit 。
max似乎不接受函數，所以我不能做function() { return this.limit }

有沒有辦法以某種方式從currentlyAdded引用limit字段，所以我可以做類似的事情

const mySchema = new Schema({
  limit: Number,
  currentlyAdded: {
    type: Number,
    max: %reference_to_limit%
  }
});

Answer 1

您可以使用validate屬性通過調用函數來驗證限制條件，

const mySchema = new Schema({
  limit: Number,
  currentlyAdded: { 
    type: Number,
    validate: [checkLimit, "Exceeded the limit!"]
  }
});

// CHECK VALIDATION
function checkLimit(currentlyAdded) {
  return currentlyAdded <= this.limit;
}