javascript - 将默认值设置为 Node js中的mongoose数组

Question

在我的模型定义中，我有:

appFeatures: [{
        name: String,
        param : [{
            name : String,
            value : String
        }]
    }]

我想为 appFeatures 设置默认值，例如:名称:'功能'，参数:[{name:'param1',value:'1'},{name:'param2',value:'2'}]

我试过了

appFeatures : { type : Array , "default" : ... }

但是它不起作用，有什么想法吗？

谢谢

Answer 1

Mongoose 允许您“分离”模式定义。两者都是为了一般的“重用”和代码的清晰度。因此，更好的方法是:

// general imports
var mongoose = require('mongoose'),
    Schema = mongoose.Schema;

// schema for params
var paramSchema = new Schema({
    "name": { "type": String, "default": "something" },
    "value": { "type": String, "default": "something" }
});

// schema for features
var featureSchema = new Schema({
    "name": { "type": String, "default": "something" }
    "params": [paramSchema]
});

var appSchema = new Schema({
    "appFeatures": [featureSchema]
});

// Export something - or whatever you like
module.export.App = mongoose.model( "App", appSchema );

因此，如果您愿意将“Schema”定义作为单个模块的一部分并使用“require”系统根据需要导入，那么它就是“干净的”和“可重用的”。如果您不想“模块化”所有内容，您甚至可以从“模型”对象“内省(introspection)”模式定义。

但大多数情况下，它允许您为默认值明确指定“您想要什么”。

对于更复杂的默认设置，您可能希望改为在“预保存” Hook 中执行此操作。作为一个更完整的例子:

var async = require('async'),
    mongoose = require('mongoose'),
    Schema = mongoose.Schema;

var paramSchema = new Schema({
  "name": { "type": String, "default": "something" },
  "value": { "type": String, "default": "something" }
});

var featureSchema = new Schema({
  "name": { "type": String, "default": "something" },
  "params": [paramSchema]
});

var appSchema = new Schema({
  "appFeatures": [featureSchema]
});

appSchema.pre("save",function(next) {
  if ( !this.appFeatures || this.appFeatures.length == 0 ) {
    this.appFeatures = [];
    this.appFeatures.push({
      "name": "something",
      "params": []
    })
  }

  this.appFeatures.forEach(function(feature) {
    if ( !feature.params || feature.params.length == 0 ) {
      feature.params = [];
      feature.params.push(
       {  "name": "a", "value": "A" },
       {  "name": "b", "value": "B" }
      );
    }
  });
  next();
});


var App = mongoose.model( 'App', appSchema );

mongoose.connect('mongodb://localhost/test');


async.series(
  [
    function(callback) {
      App.remove({},function(err,res) {
        if (err) throw err;
        callback(err,res);
      });
    },
    function(callback) {
      var app = new App();
      app.save(function(err,doc) {
        if (err) throw err;
        console.log(
          JSON.stringify( doc, undefined, 4 )
        );
        callback()
      });
    },
    function(callback) {
      App.find({},function(err,docs) {
        if (err) throw err;
        console.log(
          JSON.stringify( docs, undefined, 4 )
        );
        callback();
      });
    }
  ],
  function(err) {
    if (err) throw err;
    console.log("done");
    mongoose.disconnect();
  }
);

您可以清理它并内省(introspection)架构路径以获取其他级别的默认值。但是您基本上想说，如果未定义该内部数组，那么您将按照编码填写默认值。