Question

我有两个模式：

const categorySchema = Schema({
slug: {
    type: String,
    index: true
},
tags: {
    type: [Schema.Types.ObjectId],
        ref: 'Tag'
    }
});

和

const tagSchema = Schema({
    title: String,
    type: {
        type: String,
        enum: ['bool', 'selectable', 'int']
    },
    categories: [{
        type: Schema.Types.ObjectId,
        ref: 'Category'
    }],
    possibleValues: [String]
});

现在问题就在于此。当我尝试使用标签填充我的类别实例时，整个字段变为空数组，而当没有.populate()语句时，那里有一些ObjectId。有什么问题？

更新：这是我的查询：

models.Category
            .findOne({_id: req.params.categoryId})
            .populate('tags')
            .then(category => {
                console.log(category);
                res.send(category.tags);
            });

Answer 1

我认为您需要将category.tags的架构定义更改为：

tags: [{ 
    type: Schema.Types.ObjectId,
    ref: 'Tag'
}]

Answer 2

类别架构：

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

var categorySchema = Schema({
slug: {type: String,index: true},
tags: { type: [Schema.Types.ObjectId],ref: 'Tag'}
},{
    collection:'categories'
 });

var Category = mongoose.model('Category', categorySchema);

标记架构：

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


    var tagSchema = Schema({
    title: String,
    type: {
        type: String,
        enum: ['bool', 'selectable', 'int']
    },
    categories: [{
        type: Schema.Types.ObjectId,
        ref: 'Category'
    }],
    possibleValues: [String]
},{
    collection:'tags'
 });


var Tag = mongoose.model('Tag', tagSchema);

查询查询：

Category.
  findOne({_id: req.params.categoryId}).
  populate('tags').
  exec(function (err, categories) {
    return res.json(categories);
  });

mongoose populate使该字段为空

2 个答案: