Spring 引導 java 與 Mongodb

Question

package com.javatechie.spring.mongo.api.resource;

import java.util.List;
import java.util.Optional;

import org.bson.Document;
import org.bson.json.JsonReader;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.QualifierAnnotationAutowireCandidateResolver;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import com.javatechie.spring.mongo.api.model.Book;
import com.javatechie.spring.mongo.api.repository.BookRepository;

@RestController
public class BookController {

    @Autowired
    private BookRepository repository;

    @Autowired
    private  MongoTemplate mongoTemplate;

    @PostMapping("/addBook")
    public String saveBook(@RequestBody Book book) {
        repository.save(book);
        return "Added book with id : " + book.getId();
    }

   @GetMapping("/findAllBooks")
   public List<Book> getBooks() {
       String jsonCommand = "{ aggregate: 'Book', pipeline: [ { $project: { _id: 0, 'bookName': 1 
    } } ], cursor: { } }";
       Document resultDoc = mongoTemplate.executeCommand(jsonCommand);
       System.out.println(resultDoc);
       return repository.findAll();
   }

我可以成功地使用這個在控制台上打印一個特定的字段
String jsonCommand = "{ 聚合：'Book'，管道：[ { $project: { _id: 0, 'bookName': 1 } } ]，cursor: { } }";
但我想打印特定數據，例如在我的 bookName 字段中有很多書，所以我只想打印 Python 目前它正在打印所有 bookName。

請幫助我在這里我被困住了

Answer 1

我建議您將$match添加到您的聚合管道中。 像{$match:{ "bookName":"Python"}}