Question

我在文档内部有一个数组。

{
    "id" : "id_1",
    "name" : "name_1";
    "additionalData" : [
        {
             "additionalDataId" : "id_1_1",
             "additionalDataName" : "name_1_1",
             "longText" : "A long story about..."  
        },
        {
             "additionalDataId" : "id_1_2",
             "additionalDataName" : "name_1_2",
             "longText" : "A longer story about danger..."  
        },
        {
             "additionalDataId" : "id_1_3",
             "additionalDataName" : "name_1_3",
             "longText" : "A longer story about danger and courage"  
        },
    ]       
}

要检索名称为"name_1_2"的数组元素，请使用mongo查询。

db.collection.find( { name: "name_1"},
        { _id: 0, additionalData: { $elemMatch: { "additionalDataName": "name_1_2" } } 
    })

如何使用mongoTemplate执行相同操作？

我尝试过

Aggregation aggregation = Aggregation.newAggregation(
    Aggregation.match(
            Criteria.where("name").is("name_1").and("additionalData.additionalDataName").is("name_1_2")
        ),
    Aggregation.project("additionalData"),

）; mongoTemplate.aggregate（aggregation，“ CustmObjects”，Object.class）;

我也尝试使用ArrayOperators.Filter.filter，我用了这个答案。

Aggregation aggregation = Aggregation.newAggregation(
        Aggregation.match(Criteria.where("name").is("name_1")),
        Aggregation.project("additionalData").and(
                ArrayOperators.Filter.filter("additionalData").as("item")
                        .by(ComparisonOperators.valueOf("item.additionalDataName").equalTo("name_1_2"))
        )
    );
mongoTemplate.aggregate(aggregation, "CustmObjects", Object.class);

https://stackoverflow.com/a/46769125/4587961

无论如何，我得到的结果是数组的所有元素。请帮忙！

Answer 1

如果我正确理解了这个问题，这将提供所需的结果。

Query query = new Query(new Criteria().andOperator(
    Criteria.where("name").is("name_1"),
    Criteria.where("additionalData.additionalDataName").is("name_1_2")
));
query.fields().include("additionalData").exclude("_id");

List<Document> results = template.find(query, collectionName, org.bson.Document.class);

Java Spring-data Mongo中的Mongo DB请求

1 个答案: