Question

In order to build a simple article publishing system, all articles need to belong to one category. Ask for advice on how to design the database. One level is enough. The novice has just learned the database. .

//article model
 
 var mongoose  = require('mongoose');
 var Schema    = mongoose.Schema;
 var AticleSchema = new Schema({
 title: { type: String },
 author_id: { type: String},
 content:{type:String},
 create_at: { type: Date, default: Date.now },
 update_at: { type: Date, default: Date.now },
 
 });
 AticleSchema.index({title: 1}, {unique: true});
 mongoose.model('Aticle', AticleSchema);

Answer 1

The simplest and cruelest way is to establish two schema, one article and one article classification through table association.
1. schema of classified documents

var mongoose  = require('mongoose');
 var Schema    = mongoose.Schema;
 var ObjectId = Schema.Types.ObjectId;  //This is the relevant place
 var AticleCategorySchema = new Schema({
 Name: String, // sort name
 Aticle: [{type: objectid, ref:' aticle'}]//table association
 })

2. The schema of another article document is the same as that written by yourself, with only a few modifications.

var mongoose  = require('mongoose');
 var Schema    = mongoose.Schema;
 var ObjectId = Schema.Types.ObjectId;  //This is the relevant place
 
 var AticleSchema = new Schema({
 title: { type: String },
 author_id: { type: String},
 content:{type:String},
 create_at: { type: Date, default: Date.now },
 update_at: { type: Date, default: Date.now },
 AticleCategory:{ // association table
 type:ObjectId,
 ref:'AticleCategory'
 },
 });

The rest of the code is added in your own way.