有方法可以更新模式关联中的虚拟字段吗？

可以使用mongoose的pre中间件函数和populate方法来更新模式关联中的虚拟字段。下面是一个示例代码：

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

// 定义Author模式 const authorSchema = new Schema({ name: String });

// 声明Post模式 const postSchema = new Schema({ title: String, author: { type: Schema.Types.ObjectId, ref: 'Author' }, content: String, comments: [ { body: String, author: { type: Schema.Types.ObjectId, ref: 'Author' } } ], virtualField: String });

// 添加虚拟字段 postSchema.virtual('virtualFieldLength').get(function() { return this.virtualField.length; });

// 创建Author模型 const Author = mongoose.model('Author', authorSchema);

// 创建Post模型 const Post = mongoose.model('Post', postSchema);

// 增加pre中间件函数以更新虚拟字段 Post.updateVirtualField = function(postId, virtualField) { return Post.findById(postId) .then(post => { post.virtualField = virtualField; return post.populate('author').execPopulate(); }) .then(post => { return post.save(); }); };

// 创建一位作者 const author = new Author({ name: 'John' });

// 创建一篇帖子 const post = new Post({ title: 'Test Post', author: author._id, content: 'This is a test post!' });

// 保存作者和帖子 Promise.all([author.save(), post.save()]) .then(() => { console.log('Initial Post: ', post.toJSON());

// 更新虚拟字段
return Post.updateVirtualField(post._id, 'This is a virtual field!');

}) .then(post => { console.log('Updated Post: ', post.toJSON()); console.log('Virtual Field Length: ', post.virtualFieldLength); }) .catch(error => { console.error(error); });

在上述示例代码中，我们