如何在Mongoose模式中设置数组大小的限制

Question

您能否告诉我在创建Mongoose模式时是否有任何方法可以设置数组大小的限制。例如

 var peopleSchema = new Schema({
    name: {
        type: String,
        required: true,
        default: true
    },
   /* here I want to have limit: no more than 10 friends.
    Is it possible to define in schema?*/
    friends: [{
        type: Schema.Types.ObjectId,
        ref: 'peopleModel'
    }]
})

Answer 1

稍微调整一下架构设置，即可添加验证选项：

var peopleSchema = new Schema({
  name: {
    type: String,
    required: true,
    default: true
  },
  friends: {
    type: [{
      type: Schema.Types.ObjectId,
      ref: 'peopleModel'
    }],
    validate: [arrayLimit, '{PATH} exceeds the limit of 10']
  }
});

function arrayLimit(val) {
  return val.length <= 10;
}