在Rust中使用正则表达式查询MongoDB

[dependencies]
mongodb = "2.0"
regex = "1.3"

use mongodb::{Client, options::ClientOptions};
use regex::Regex;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // 设置MongoDB连接选项
    let mut client_options = ClientOptions::parse("mongodb://localhost:27017").await?;
    client_options.app_name = Some("MyApp".to_string());

    // 连接MongoDB
    let client = Client::with_options(client_options)?;

    // 获取数据库和集合
    let db = client.database("mydb");
    let collection = db.collection("mycollection");

    // 构建正则表达式查询条件
    let regex = Regex::new(r"pattern").unwrap();
    let filter = doc! { "field": { "$regex": regex.to_string() } };

    // 执行查询
    let cursor = collection.find(filter, None).await?;

    // 处理查询结果
    while let Some(result) = cursor.next().await {
        match result {
            Ok(document) => {
                // 处理查询结果的文档
                println!("{:?}", document);
            }
            Err(e) => {
                // 处理查询错误
                eprintln!("Error: {}", e);
            }
        }
    }

    Ok(())
}