Question

假设我有一个猫鼬模型和一个基于偶然性的值

const findUser = async (username, email) => {
  let foo = null
 
  if (Math.random() > 0.5) foo = "hi" // `foo` now has a chance of turning from null to "hi"

  UserModel.find({ "username": username, "email": email, "winner": foo === null ? 'EXCLUDE THIS SEARCH VALUE' : foo
}

^ This is some real code, in combination with some pseudo code ^

我可以这样实现：

const findUser = async (username, email) => {
  let foo = null
 
  if (Math.random() > 0.5) foo = "hi" // `foo` now has a chance of turning from null to "hi"

  let result;
  if(foo === null)
    result = await UserModel.find({ "username": username, "email": email });
  else
    result = await UserModel.find({ "username": username, "email": email, "winner": foo });
  // ^^ Now I have to type the same thing all over again..
  // I'm wondering if there is a way to include it conditionally?
}

但是这里的问题是我必须再次输入相同的内容，只是要包含另一个字段。有没有一种方法可以在搜索中适当地包含一列？

Answer 1

可能有一种更简单/更好的方法来实现此目的，但是在这种情况下，我要做的就是构建一个像这样的对象。

const findUser = async (username, email) => {
  let foo = null

  let query = {
   username,
   email
  }
 
  if (Math.random() > 0.5) foo = "hi" // `foo` now has a chance of turning from null to "hi"

  if (foo != null) {
    query.winner = foo;
  }

  UserModel.find(query);
}

基本上，创建一个默认对象，该对象中将始终带有您的属性。然后检查您的foo值是否不为null。并且，如果它不为null，则将其添加到查询中，然后将该查询对象传递到查找中。

Answer 2

您可以将查询提取到变量中，然后根据foo的值进行操作。

const findUser = async (username, email) => {
   let foo = null

   if (Math.random() > 0.5) foo = "hi"

   const query = { username, email }

   if (foo) {
      query.winner = foo
   }

   const result = await UserModel.find(query)
}

猫鼬忽略查找中的列，如果该值为空

2 个答案: