MongoDB-Spring Data获取仅包含请求字段的文档（不多不少）

Question

我将MongoDB与Spring Boot 2.0和Spring Data结合使用。 我对MongoDB有以下要求

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "parameters": [
         {
            "name": "test-param-name1",
            "value": "test-param-value1"
         }
    ]
}

例如，在MongoDB中，我有以下文档：

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "body" : "<response><rating>0.5</rating></response>",
    "parameters": [
      {
         "name": "test-param-name1",
         "value": "test-param-value1"
      },
      {
         "name": "test-param-name2",
         "value": "test-param-value2"
      }
     ]
}

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "body" : "<response><rating>0.5</rating></response>",
    "parameters": [
         {
            "name": "test-param-name1",
            "value": "test-param-value1"
         }
    ]
}

在我的回复中，我只想看到一个严格响应请求搜索参数的文档，它必须是：

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "body" : "<response><rating>0.5</rating></response>",
    "parameters": [
             {
                 "name": "test-param-name1",
                 "value": "test-param-value1"
             }
    ]
}

我能否在Spring Data的帮助下构建查询以仅获取严格响应我的请求字段的文档（而不包含更多或更少的字段）？

Answer 1

您可以使用MongoOperations，AggregationOperation和Aggregation在数组中进行搜索，如下所示：

    ApplicationContext ctx = new AnnotationConfigApplicationContext(MongoConfig.class);
    MongoOperations mongoOperation = (MongoOperations) ctx.getBean("mongoTemplate"); 

    AggregationOperation match = Aggregation.match(Criteria.where("cra").is("test-cra"));
    AggregationOperation unwind = Aggregation.unwind("parameters");
    AggregationOperation match2 = Aggregation.match(Criteria.where("parameters.value1").is("test-param-value1"));


    Aggregation aggregation = Aggregation.newAggregation(match, unwind, match2);

    AggregationResults<AggregateFactoryResult> output = mongoOperation.aggregate(aggregation, "tablename", AggregateFactoryResult.class);