Mongoose聚合管道中实现字符串匹配与筛选的教程

const uniqueQuoteAuthors = await QuoteModel.aggregate().group({
  _id: "$author",
  count: { $sum: 1 },
});

// 在内存中进行筛选，效率较低
const filteredData = uniqueQuoteAuthors.filter((value) => {
  return value._id.toLowerCase().includes(searchWord.toLowerCase());
});

import mongoose from 'mongoose';

// 假设配置信息已定义
const config = {
    MONGODB_URI: 'mongodb://localhost:27017/testdb'
};

// 定义Mongoose Schema和Model
const quoteSchema = new mongoose.Schema({
    author: String,
    quote: String,
});
const QuoteModel = mongoose.model('Quote', quoteSchema); // 注意：Model名称通常首字母大写

(async function main() {
    try {
        // 连接到MongoDB数据库
        await mongoose.connect(config.MONGODB_URI);
        console.log('MongoDB connected successfully.');

        // 清空集合并插入测试数据
        // 使用catch来处理集合不存在时的drop操作，避免首次运行报错
        await QuoteModel.collection.drop().catch((err) => {
            if (err.code === 26) { // 26是集合不存在的错误码
                console.log('Collection did not exist, skipping drop.');
            } else {
                throw err; // 其他错误则抛出
            }
        }); 
        await QuoteModel.create([
            { author: 'Martin Luther King Jr', quote: 'I have a dream.' },
            { author: 'Friedrich Nietzsche', quote: 'God is dead.' },
            { author: 'Marcus Tullius Cicero', quote: 'A room without books is like a body without a soul.' },
            { author: 'Andre Gide', quote: 'It is better to be hated for what you are than to be loved for what you are not.' },
            { author: 'Martin Luther King Jr', quote: 'Darkness cannot drive out darkness.' },
            { author: 'Jack London', quote: 'The proper function of man is to live, not to exist.' },
            { author: 'John Doe', quote: 'Hello world.' },
            { author: 'Jane Doe', quote: 'Goodbye world.' },
        ]);
        console.log('Test data seeded.');

        // 定义搜索词
        const searchWord = 'king'; // 尝试搜索 "King" 或 "king"

        // 使用聚合管道进行分组和筛选
        const uniqueQuoteAuthors = await QuoteModel.aggregate([
            {
                // 第一阶段：按作者分组并计数
                $group: {
                    _id: '$author', // 分组键是作者名
                    count: { $sum: 1 }, // 计算每个作者的引用数量
                },
            },
            {
                // 第二阶段：对分组后的结果进行匹配筛选
                // 筛选条件：_id（即作者名）包含搜索词，且大小写不敏感
                $match: {
                    _id: { $regex: searchWord, $options: 'i' },
                },
            },
        ]);

        console.log('搜索结果 (uniqueQuoteAuthors): ', uniqueQuoteAuthors);

        // 另一个搜索示例：搜索 "doe"
        const searchWord2 = 'doe';
        const authorsWithDoe = await QuoteModel.aggregate([
            {
                $group: {
                    _id: '$author',
                    count: { $sum: 1 },
                },
            },
            {
                $match: {
                    _id: { $regex: searchWord2, $options: 'i' },
                },
            },
        ]);
        console.log('搜索结果 (authorsWithDoe): ', authorsWithDoe);

    } catch (error) {
        console.error('发生错误:', error);
    } finally {
        // 关闭数据库连接
        await mongoose.connection.close();
        console.log('MongoDB connection closed.');
    }
})();

搜索结果 (uniqueQuoteAuthors):  [ { _id: 'Martin Luther King Jr', count: 2 } ]

搜索结果 (authorsWithDoe):  [ { _id: 'John Doe', count: 1 }, { _id: 'Jane Doe', count: 1 } ]