如何使用 MongoTemplate 将 Mongo Shell 脚本转换为 Java？答案

【问题标题】：How to turn Mongo Shell script into Java using MongoTemplate?如何使用 MongoTemplate 将 Mongo Shell 脚本转换为 Java？
【发布时间】：2020-05-07 11:13:29
【问题描述】：

我的 Mongo Shell 脚本：

db.getCollection('order').aggregate([
  { $match: { clientId: "test@gmail.com" } },
  { $lookup: { from: 'ordereddevice', localField: 'id', foreignField: 'order', as: 'orderedDevices' } }
])

我用的是这样的：

MongoClientURI connectionString = new MongoClientURI("mongodb://localhost:27017");
MongoClient mongoClient = new MongoClient(connectionString);
MongoDatabase database = mongoClient.getDatabase("db_name");
MongoCollection < Document > collection = database.getCollection("order");
List < Document > pipeline = Arrays.asList(new Document().append("$match", new Document().append("clientId", "test@gmail.com")), new Document().append("$lookup", new Document().append("from", "ordereddevice").append("localField", "id").append("foreignField", "order").append("as", "orderedDevices")));
Block < Document > printBlock = new Block < Document > () {
    @Override public void apply(final Document document) {
        System.out.println(document.get("_id"));
    }
};
collection.aggregate(pipeline).forEach(printBlock);

但它会重新连接MongoDB，所以我正在寻找一种使用MongoTemplate的方法来做到这一点

【问题讨论】：

这里是参考文档，其中包含使用 mongoTemplate 的示例。请发布您的任何具体问题。您只是想使用mongoTemplate还是有具体问题吗？

标签： java mongodb spring-boot mongotemplate mongorepository

【解决方案1】：

感谢您的文档，自己完成吧！哈哈

    @Autowired
    MongoTemplate mongoTemplate;

    @Override
    public List<OrderedDeviceByOrderId> findOrderedDeviceByOrderId(String clientid) {
        AggregationOperation lookup = Aggregation.lookup("ordereddevice","_id","order","Devices");
        AggregationOperation match = Aggregation.match(Criteria.where("clientId").is(clientid));
        Aggregation agg = Aggregation.newAggregation(match, lookup);

        AggregationResults<OrderedDeviceByOrderId> results = mongoTemplate.aggregate(agg, "order", OrderedDeviceByOrderId.class);
        List<OrderedDeviceByOrderId> orderedDeviceByOrderId = results.getMappedResults();

        orderedDeviceByOrderId.forEach(s -> System.out.println(s));
        return orderedDeviceByOrderId;
    }

【讨论】：